Patients admitted to the intensive care unit (ICU) often require invasive mechanical ventilation. Ventilator-associated lower respiratory tract infections (VA-LRTI), either ventilator-associated tracheobronchitis (VAT) or ventilator-associated pneumonia (VAP), are the most common complication among this patient cohort. VAT and VAP are currently diagnosed and treated as separate entities, viewed as binary disease elements despite an inherent subjectivity in distinguishing them clinically. This paper describes a new approach to pulmonary infections in critically ill patients. Our conjecture is that the host-pathogen interaction during mechanical ventilation determines a local compartmentalized or systemic de-compartmentalized response, based on host immunity and inflammation, and the pathogenic potential of the infecting organism. This compartmentalized or de-compartmentalized response establishes disease severity along a continuum of colonization, VAT or VAP. This change in approach is underpinned by the dissemination hypothesis, which acknowledges the role of immune and inflammatory systems in determining host response to pathogenic organisms in the lower respiratory tract. Those with intact immune and inflammatory pathways may limit infection to a compartmentalized VAT, while immunosuppressed mechanically ventilated patients are at greater risk of a de-compartmentalized VAP. Taking this model from the realm of theory to the bedside will require a greater understanding of inflammatory and immune pathways, and the development of novel disease-specific biomarkers and diagnostic techniques. Advances will lead to early initiation of optimal bespoke antimicrobial therapy, where the intensity and duration of therapy are tailored to clinical, immune and biomarker response. This approach will benefit towards a personalized treatment. Patients admitted to the intensive care unit (ICU) often require organ support. Invasive mechanical ventilation, while a widely acknowledged lifesaving lung support, may be associated with deleterious effects. Ventilator-associated lower respiratory tract infections (VA-LRTI), either ventilator-associated tracheobronchitis (VAT) or ventilator-associated pneumonia (VAP), are the most common complications encountered during invasive mechanical ventilation.VAP is a well-described and widely studied clinical entity and is linked to enhanced morbidity and mortality globally , 2. SignVAT and VAP are currently diagnosed and treated as separate entities, viewed as binary disease elements despite an inherent subjectivity in distinguishing them clinically. While 1 week of treatment is currently recommended for VAP, it is still being discussed if treatment for VAT is necessary, and if so for how long.5 or > 104 colony-forming units (CFU) per mL of a potentially pathogenic microorganism in the ETA or BAL respectively [A new approach conceives colonization, VAT and VAP as a continuum of lower respiratory tract inflammation and infection. Colonization is the microbiological growth of potentially pathogenic microorganisms in tracheobronchial samples, endotracheal aspirates (ETA) or bronchoalveolar lavage (BAL), with no features of systemic infection. VAT represents an intermediate process between colonization and VAP. No gold standard definition exists for VAT, and this has led to different diagnostic criteria being applied. The Center for Disease Control (CDC) defines VAT as an absence of pneumonia on the chest radiograph (CXR) and at least two of the following: fever > 38 °C), cough, new or increased production of sputum, rhonchi and wheezing, or bronchospasm. Additionally, the culture of tracheobronchial secretions obtained by ETA or bronchoscopic technique should be positive . In more °C, cougectively . ClinicaVAT and VAP have similar diagnostic criteria and are distinguished by the presence or absence of pulmonary infiltrates on CXR. Making a differential diagnosis on the basis of CXR is difficult –15. OccaWe propose a radically different approach to the diagnosis of pulmonary infections in critically ill patients. Our conjecture is that the host-pathogen interaction during mechanical ventilation determines a local compartmentalized or systemic de-compartmentalized response, based on host immunity and inflammation, and the pathogenic potential of the infecting organism. This compartmentalized or de-compartmentalized response establishes disease severity along a continuum of colonization, VAT or VAP.This approach requires a fundamental change in how we view respiratory infections in invasive mechanically ventilated patients, from the current binary model to a continuum determination. This paradigm shift is underpinned by a dissemination hypothesis, which acknowledges the role of the immune and inflammatory systems in determining host response to pathogenic organisms in the lower respiratory tract. Those with intact immune and inflammatory pathways may limit infection to a compartmentalized VAT, while immunosuppressed mechanically ventilated patients are at greater risk of a de-compartmentalized local immune VAP Fig. .Fig. 1DiBringing the dissemination model from the realm of theory to the bedside will require a greater understanding of inflammatory and immune pathways, and the development of novel disease-specific biomarkers and diagnostic techniques to track host response to pathogenic organisms. While a knowledge gap currently exists in this area, work is on-going that will identify these pathways and devise specific markers linked to both VAT and VAP, with subsequent incorporation into diagnostic, therapeutic and predictive algorithms.Biomarkers are proposed to have a role in the identification of new infections, distinguishing infection from inflammation, predicting severity on an individual basis, and tracking response to therapy. Despite growing research interests, biomarkers have so far failed to meet these identified needs , 20. CliThe use of systemic inflammation markers, such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and white blood cell count (WBC), is of limited utility in current clinical practice due to their poor sensitivity and specificity. Procalcitonin (PCT) has also been introduced as a valuable biomarker for bacterial infection detection. However, all of the aforementioned “traditional inflammatory biomarkers” are still far from being both specific and sensitive in VAP . PotentiIn the absence of specific biomarkers, therapy is generally empiric with little ability to instigate personalized therapy. Patients are diagnosed according to algorithms and treated by the protocol. Antimicrobial therapy is excessive for some, but inadequate for others. Effective antimicrobial stewardship programmes are impeded by a lack of accurate information regarding the appropriateness of instituted antimicrobial therapy. This may contribute to overuse of antimicrobial, inappropriate duration of therapy and emergence of resistant organisms , 28.As a new model of respiratory infection, there are few studies evaluating the role of biomarkers to distinguish colonization, VAT and VAP. Extrapolated findings suggest CRP is static between VAT and subsequent development of VAP, while PCT demonstrated a significant rise as the continuum progressed . The potIn the future, disease-specific biomarkers may enable accurate recognition of the compartmentalized immune response in lower respiratory infections, defining progression through colonization, VAT and VAP and tracking response to antimicrobial therapy.Critically ill patients are considered to exist in a state of reduced immune and inflammatory function, with the majority of research coming from those with sepsis –35. A grIn a recent prospective observational study, intubated patients with de-compartmentalized VAP displayed a transcriptomic signature indicating relative immune synapse depression, when compared with mechanically ventilated patients who did not develop VAP . Microarp < 0.0001)  miniaturized technology is an exciting prospect, which would provide comprehensive analytical data to the ICU clinician in a timely fashion.Microfluidic lab-on-a-chip (LOC) devices are a class of devices that may represent the future of bedside diagnostics for critically ill patients –40. MuchA number of ultra-sensitive assays have been developed in the last few years that may facilitate this transfer of diagnostics from the traditional laboratory to the bedside. Such diagnostics are centered on LOC enzyme-linked immunosorbent assays (ELISA) or lab-on-bead nanoparticles.Timely and accurate POC diagnostics are the future and should enable informed rapid critical care decision-making resulting in improved patient outcomes.Improved diagnostic pathways and a greater understanding of the role of host-pathogen interaction, systemic biomarkers and immune function should enable progress towards the provision of personalized medicine in the critical care setting.Progressing to a model of individualized patient assessment and decision-making has the potential to fundamentally alter how we make clinical decisions on a daily basis. Most conventional methods biomarker detection such as microwell plate-based immunoassay and polymerase chain reaction often suffer from high costs, low test speeds and complicated procedures. In addition to clinical assessment, imagine a detailed overview of patient immune function, biomarker trends, and pathogenic organism status, all at the bedside with a high degree of sensitivity and specificity. Mechanically ventilated patients may be stratified according to whether pathogenic organisms are likely to trigger a compartmentalized (VAT) or de-compartmentalized (VAP) immune response. The decision to institute antimicrobial therapy will be more informed, as will the choice of agent and duration of therapy. New disease scoring systems and prognostic calculators are likely to arise as our knowledge and experience with such an approach, ultimately enabling clinicians make more accurate outcome predictions on an individual patient basis.Our approach to respiratory infections in mechanically ventilated patients will change dramatically in the future. Colonization, VAT and VAP will be seen as a continuum, replacing the current binary model of disease. The research will accurately characterize immune and inflammatory pathways, enhancing our understanding of the host-pathogen interaction, and identify clinically relevant disease-specific biomarkers. Unique immunological “fingerprints” will provide a panel of biomarkers for each individual mechanically ventilated patient, which can be used to anticipate progression to VA-LRTI, whether this will lead to a compartmentalized VAT or a de-compartmentalized VAP, and predict adverse outcomes.A capacity to predict the onset and severity of VA-LRTI will dramatically alter antimicrobial prescribing in these critically ill patients. Clinicians can logically individualize antimicrobial therapy based on validated biomarkers and unique immune fingerprints, replacing the less than optimal situation currently in place. Choosing single or multi-drug regimens, altering commencement and duration of therapy, and tracking therapeutic response will individualize antimicrobial prescribing. A more logical and objective system for antimicrobial prescribing will curtail the overall usage of antimicrobial agents, and delay or prevent the emergence of resistant pathogens.Antimicrobial stewardship is clearly of vital long-term importance, but a newer approach to prescribing will also have short-term benefits for individual patients. Early initiation of optimal bespoke antimicrobial therapy, where the intensity and duration of therapy is tailored to clinical, immune and biomarker response, will reduce progression to overwhelming infection and improve survival.New platforms not only enable better provide attractive characteristics such as label-free detection and improved sensitivity with the implementation of the integration of various novel detection techniques but also sample preparation, chemical manipulation and reaction, high-throughput and portability. All of these aforementioned features can potentially improve the performance for diagnosis and ultimately impact the biomarker’s detection process. Although considered dramatic, a new future of respiratory infections in mechanically ventilated patients will facilitate early intervention and optimization of antimicrobial therapy. This approach will benefit the individual patient, and through improved antimicrobial stewardship, society as a whole.Clinician understanding of the host-pathogen interaction during mechanical ventilation is evolving, and it is time to recognize a continuum exists between colonization of the lower respiratory tract, VAT and VAP. This paradigm shift is underpinned by the dissemination hypothesis, which acknowledges the role of the immune and inflammatory systems in determining host response to pathogenic organisms in the lower respiratory tract. Personalized medicine centered on bedside diagnostics assisting rapid clinical decision is on the horizon. The approach to respiratory infections is evolving, and while the future is not yet clear, it is certainly exciting.No two individual patients are exactly the same, and we look forward to the day our diagnostic and therapeutic strategy can take this into account.


Although there is general consensus that altered brain structure and function underpins addictive disorders, clinicians working in addiction treatment rarely incorporate neuroscience-informed approaches into their practice. We recently launched the Neuroscience Interest Group within the International Society of Addiction Medicine (ISAM-NIG) to promote initiatives to bridge this gap. This article summarizes the ISAM-NIG key priorities and strategies to achieve implementation of addiction neuroscience knowledge and tools for the assessment and treatment of substance use disorders. We cover two assessment areas: cognitive assessment and neuroimaging, and two interventional areas: cognitive training/remediation and neuromodulation, where we identify key challenges and proposed solutions. We reason that incorporating cognitive assessment into clinical settings requires the identification of constructs that predict meaningful clinical outcomes. Other requirements are the development of measures that are easily-administered, reliable, and ecologically-valid. Translation of neuroimaging techniques requires the development of diagnostic and prognostic biomarkers and testing the cost-effectiveness of these biomarkers in individualized prediction algorithms for relapse prevention and treatment selection. Integration of cognitive assessments with neuroimaging can provide multilevel targets including neural, cognitive, and behavioral outcomes for neuroscience-informed interventions. Application of neuroscience-informed interventions including cognitive training/remediation and neuromodulation requires clear pathways to design treatments based on multilevel targets, additional evidence from randomized trials and subsequent clinical implementation, including evaluation of cost-effectiveness. We propose to address these challenges by promoting international collaboration between researchers and clinicians, developing harmonized protocols and data management systems, and prioritizing multi-site research that focuses on improving clinical outcomes. The past two decades have seen significant advances in our understanding of the neuroscience of addiction and its implications for practice [reviewed in –3]. HoweNeuropsychological studies consistently demonstrate that many people with SUD exhibit mild to moderately severe cognitive deficits in processing speed, selective, and sustained attention, episodic memory, executive functions , decision-making and social cognition –10. FurtCognitive deficits in SUD have moderate longevity, and although there is abstinence-related recovery –16, thesThe workforce in the SUD specialist treatment sector is diverse, encompassing medical specialists, allied health professionals, generalist health workers, and peer and volunteer workers . For insTwo fields in particular have driven progress in cognitive assessment practice for generalist workers: dementia, with an increasing emphasis on screening in primary care , 27, andTo date, the majority of the published literature on routine cognitive screening in SUD contexts has focused on three tests commonly used in dementia screening –34: the ™ . Attention, memory, EF, and decision-making are the most commonly assessed domains, although there is a considerable discrepancy in the tests selected to assess these constructs . Even wi™  are exam™ , 46–48, via smartphone devices . Evaluations of the reliability, validity, and feasibility of mobile cognitive assessment in individuals with SUD have been scarce, but promising , Immediate Post-concussion Assessment and Cognitive Testing battery (ImPACT), and CogState brief battery, have been used more widely, although validation studies to date suggest they may not yet have sufficient psychometric evidence to support clinical use –53. Rese devices   (Cognitive assessment nt (EMA) . The flent (EMA) , the rapnt (EMA) . Similarnt (EMA) –61, whernt (EMA) , 61. Hownt (EMA) .A substantial proportion of people with SUD have cognitive deficits. Alcohol, stimulants and opioid users have overlapping deficits in EF and decision-making. Alcohol users have additional deficits in learning and memory and psychomotor speed. Heavy cannabis users have specific deficits in episodic memory and attention. Cognitive assessments of speed/attention, EF and decision-making are meaningfully associated with addiction treatment outcomes such as treatment retention, relapse and quality of life . In addiOne of the main challenges for the cognitive assessment of people with SUD is the disparity of tests applied across sites and studies, and the lack of a common ontology and harmonized assessment approach , 62. FurAs the authors of this ISAM-NIG roadmap, we give the following recommendations for future work: Selecting theoretically and clinically relevant constructs: We recommend prioritizing constructs that are theoretically implicated in current neurobiological models of SUD . Th. Th102)]versus current cigarette smokers (> 12 month abstinent)  , 112, anon-users .Emerging (but mixed) evidence showed that abstinence duration was associated with improved integrity  of cortical and prefrontal pathways , 114. Adbrain structure in people with nicotine and alcohol use disorders reported that increased volume and white matter integrity in prefrontal regions, followed by parietal and subcortical areas, most consistently segregated abstainers versus relapsers   brain integrity in SUD predicts abstinence, with promising results. Studies of elapsers –119. Stucessing) , 120–124isorders , 124. Alisorders . Studiesisorders , 126 andisorders .Novel training strategies that target core cognitive dysfunctions in SUD have shown promise to restore cognitive alterations and help maintain abstinence . One exaEarly neuroimaging evidence has examined the neuroadaptations that occur pre-to-post-cognitive bias modification training. These findings are revised and discussed in the COGNITIVE TRAINING AND REMEDIATION section below. There is a paucity of neuroimaging research on other cognitive training and remediation approaches, despite promising evidence of neuroplasticity-related changes after cognitive remediation in brain injury .focused attention, which consists of paying attention to a specific stimulus while letting go of distractions  and (ii) open monitoring, which refers to the being aware of internal and external stimuli  with a non-judgmental attitude and acceptance.Mindfulness-based interventions are being increasingly used for the treatment of SUD . Althougversus placebo intervention, decreased activity of the ventral striatum, and medial prefrontal regions during a craving task and an emotion regulation task  and brain changes related to abstinence were compared to different types of controls . Third, repeated measures study designs had varying data testing points  that precluded the integration of the study findings and mapping treatment-related, trajectories of brain changes with abstinence/recovery. More systematic evidence is needed to provide sufficient power to measure brain pathways relevant to treatment response and to inform clinically-relevant treatment endpoints. In order to address this gap, the ISAM-NIG Neuroimaging stream recommends the conduct of harmonized, multi-site, neuroimaging studies with systematic testing protocols of relevance for clinical practice. It is hoped that the ISAM-NIG Neuroimaging approach will generate results that can be readily integrated and that increase the power to detect abstinence-related neuroadaptations.Overall, there is a paucity of neuroimaging studies of treatment and abstinence in SUD. The study methods are very heterogeneous which precludes their systematic integration. On one hand, the integration of neuroimaging testing into clinical practice can be challenging. MRI scanners are extremely expensive to buy, setup, and run safely, and the acquisition of high-quality brain images requires extensive specialized technical expertise. On the other hand, the availability of MRI scans in many hospitals, universities, and medical institutions, may provide ideal settings to integrate neuroimaging and clinical expertise. MRI scans can be feasible in that they are non-invasive, safe, and can be relatively quick . Outstanding challenges to address remain funding sources, the lack of integration in the theoretical frameworks between basic research, clinical science, and clinical practice. Discipline-specific specialized language and practices can also create barriers. We advocate using team science to develop a harmonized interdisciplinary framework, so that all stakeholders, including clinicians, neuropsychologists, social workers and neuroscientists interact to inform commonly-agreed testing batteries and most profitable directions for future work.The present review has focused on neuroimaging data mainly acquired through fMRI, allowing for visualization of the brain networks involved in certain conditions . However, it should be noted that the coarse temporal resolution of such techniques (1–2 s) impedes determination of the temporal activation sequence (in the order of the ms), allowing the specific brain activation patterns to be correlated with the various cognitive stages involved in the investigated processes . Other We aim to map how advanced multimodal neuroimaging tools—coordinated with relevant clinical and cognitive measures agreed upon with a large multidisciplinary team of experts in the field—can be used to track the neurobiological mechanisms of addiction treatment. As the authors of this ISAM-NIG roadmap, we give the following recommendations for future work: harmonized with clinical and cognitive tools mapping overlapping systems .Neuroimaging testing should be neuroimaging measures of brain integrity other than those included in the harmonized protocols when focused on discovery science . This would mitigate the risks that complete harmonization around existing neuroimaging measures and neurobiological models of addiction would stifle new knowledge. We cannot exclude that current neuroimaging techniques and theories of addiction may not be an accurate/valid representation of brain changes that occur with SUD treatment.Neuroimaging protocols may also incorporate amenable to repeated testing so that changes over time can be tracked (i) prospectively, to examine if baseline imaging measures predict follow up outcomes assessed 1+ times at the end of treatment, (ii) longitudinally, to track individual trajectories of brain and behavioral change before, during and after treatment, (iii) using rigorous double-blind randomized controlled studies to map treatment-specific effects in distinct substance and behavioral addictions.Imaging testing batteries should be Multi-site neuroimaging studies using shared protocols will be necessary to gain sufficient power to track heterogeneity of treatment responses between individuals SUD, to validate the protocols and test their reliability. There are excellent examples of successful international collaborations that are already in place in this area, such as ENIGMA-Addiction  or as discrete measures of addiction  and related mental health, cognitive and quality of life outcomes .Brain indices from neuroimaging testing should be Despite recent advances in psychological and pharmacological interventions for SUD, relapse remains the norm. A recent meta-analysis of 21 treatment outcome studies conducted between 2000–2015 found that fewer than 10% of treatment seekers were in remission  in any given year following SUD treatment . The pasIn SUD, general cognitive remediation approaches such as cognitive enhancement therapy (CET) and cognitive remediation therapy (CRT) aim to reduce substance use –150 and Another manualized therapist-assisted group intervention is Goal Management Training (GMT), which trains EF and sustained attention and emphasizes the transfer of these skills to goal-related tasks and projects in everyday life. When combined with mindfulness meditation, GMT has been found to significantly improve WM, response inhibition and decision-making in alcohol and stimulant outpatients relative to TAU  and moreThe most widely researched EF training intervention, WMT  , 162 reqSince deficits in inhibitory control are associated with increased drug use –174, ICTTwo meta-analyses recently concluded that ICT leads to small but robust reductions in alcohol consumption immediately after training , 179. DiCBM aims to directly interrupt and modify automatic processes in response to appetitive cues. Attentional bias modification (AtBM) aims to modify the preferential allocation of attentional resources to drug cues by repeatedly shifting attention to neutral or positive (non-drug) cues and away from drug-related cues. Despite several null findings , signifiApproach bias modification (ApBM), which uses the Approach Avoidance Task, requires an avoidance response to drug cues  and an approach response  to non-drug cues. Several trials have examined alcohol ApBM, with evidence that short-term abstinence is increased by up to 30% with four consecutive training sessions during inpatient withdrawal  and by 8versus soft drink stimuli)  , 195. Pastimuli) , 195. Thstimuli) , 195. Nostimuli) , 195 butTo date, only one study has been published that trialled ApBM in an illicit drug-using sample of non-treatment-seeking adults with cannabis use disorder (N = 33). Relative to sham-training, four sessions resulted in blunted cannabis cue-induced craving  but not Finally, a meta-analysis of alcohol and smoking CBM studies (both AtBM and ApBM) showed a small but significant effect on clinical outcomes for alcohol (but not smoking), but a lack of evidence that reduced approach bias led to improved outcomes . This as,s capacity to repair itself (neuroplasticity) during withdrawal, early and later abstinence by strengthening cognitive control  and dampening cue-reactivity , prior to engaging in more intensive and cognitively demanding but ecologically valid group training for more extensive remediation .Currently CBM, particularly ApBM, appears one of the most promising approaches for individuals seeking treatment for AUDs; however, its effectiveness for other drugs (aside from tobacco) is yet to be established. The most extensively trialled CT approach is WMT, which has shown promising results in alcohol and stimulants users. However, its high cognitive demand, training intensity, and apparent lack of far-transfer effects limit its application to clinical populations. ICT holds much promise for reducing alcohol consumption in heavy drinkers, but requires testing in treatment-seekers. Finally, more intensive group-based approaches such as CRT/CET and GMT may improve EF and quality of life; however, their impact on substance use outcomes remains largely untested. Synergistic approaches now warrant exploration. Indeed, a study that combined WMT and AtBM  has showWhile there may be logistical challenges to the adoption of CT in clinical practice , the main impediment to implementing CT in clinical practice is the absence of robust evidence for treatment success of any one particular approach. This is largely due to the vast heterogeneity of studies, particularly regarding differences in treatment settings, samples , cognitive intervention approaches, number and duration of training sessions, targeted mechanisms, targeted drugs of concern and varying primary outcome measures. Similarly, the absence of brief, ecologically valid, easily-administered measures of cognition precludes the identification of candidates who are most likely to benefit from CT . As such, the evidence base for CT remains hampered by (1) the marked lack of studies on clinical populations, (2) the counter-intuitive neglect of assessing relevant substance use outcomes, (3) the lack of adequately-powered RCTs, (4) the limitations of research designs, (5) lack of attention to individual-level trajectories of cognitive improvements in relation to substance use and quality of life outcomes (precision medicine approach), and (6) a simple focus on direct relations between cognitive deficits and outcomes without considering person and environmental mediators and moderators of this relation . DespiteAs the authors of this ISAM-NIG roadmap, we give the following recommendations for future work: The a priori publishing of research protocols: To improve the consistency of cognitive training trials we encourage the publishing of research methodologies and protocols. This will permit replication studies to aid the consolidation of a disparate evidence base and help determine the optimal training duration and frequency to be implemented in real world clinical settings.Adopting consistent training paradigms and tailored, context-relevant stimuli: A challenge for CBM research is the absence of consensus on optimal sham training conditions  and optimal approach stimuli  (verages) . In the Ensuring targeted constructs are measured in cognitive training trials: Future research protocols must adopt pre- and post-intervention measures that will elucidate changes in targeted mechanisms, thereby integrating neuroscience into addiction treatment. Importantly, these protocols should enable moderation and mediation analyses using psychophysiological measures  in order to address issues regarding the notorious lack of reliability of traditional measures  (ce task) , 202 andAdopting and standardizing SUD-related outcome measurement: Future research needs to test cognitive interventions in real-world clinical settings and assess meaningful SUD clinical outcomes . Clear evidence of reduced harm and consumption is likely to appeal to both clinicians and individuals under their care, thus driving this improved addiction treatment effort.The exponential growth in our understanding of the neural circuits involved in drug addiction over the last 20 years , 203–205positive valence, negative valence, and cognitive systems with a predominant focus on EF  have provided a research framework for mental health disorders that include these levels of targets for neuroscience-informed interventions including neuromodulation. While this framework was not specifically designed for addiction science, it is still a helpful resource. In RDoC terminologies, three main domains are more frequently considered for addiction medicine: us on EF , 207. Wius on EF . For morThere is a trend of reporting positive results in tDCS and rTMS trials in SUD that is being reflected in systematic reviews and meta-analysis. In a meta-analysis published in 2013 on 17 eligible trials, Jansen, et al., reported that rTMS and tDCS on DLPFC could decrease drug craving . A meta-Application of other areas of NIBS such as FUS, tNS in addiction medicine is limited to a few case reports. Beyond NIBS, invasive brain stimulation technologies like deep brain stimulation (DBS) are only just emerging as approaches in addiction medicine with only a few case reports or pilot trials in the literature. Consequently, the lack of robust evidence for invasive neuromodulation precludes any judgment regarding its clinical utility.There are 96 original tES/TMS publications in addiction medicine as of May 1, 2019 mainly reporting positive results with one to over 20 sessions of stimulation Figure 2How to move beyond single session interventions: 44% of the tES/TMS studies have recruited a single session of intervention to investigate potential effects to then move forward to multiple session studies  key neuromodulation targets, (ii) their relevant substance use, cognitive, and clinical outcomes, as different brain pathways are ascribed to heterogeneous neurobehavioral processes , after early abstinence (maintenance)] and contextual treatment  in parallel to neuromodulation are important areas for future explorations with specific considerations in different SUDs.How to optimize the large parameter space within each NIBS technology at the individual level: There is a new effort to optimize the stimulation parameter for each individual subject based on their subjective responses or objective biomarkers in closed-loop stimulation. Bayesian optimization protocols have introduced an interesting area with initial positive response with transcranial alternating current (tACS) stimulation (a priori brain regions (or their connectivity) across various individuals . These protocols have often been used in conjunction with sensorimotor rhythm training  to improvia surface EEG. Feedback can be provided on the level of activity of single or multiple a priori regions of interest, the strength of the connectivity between multiple regions, and patterns of brain activity identified with machine learning methods  -based neurofeedback has the potential to provide insight in understanding the mechanisms of SUD underpinned by deep brain nuclei  the actmachine) . A handfmachine) ]. This bmachine) –230 and machine) , 232.a priori brain regions of interest, most commonly the anterior cingulate cortex, medial prefrontal cortex, and other regions—as well as brain connectivity—were used as source for feedback from single studies . Several neurofeedback studies required participants to modulate brain function during craving tasks . This body of work shows that patients could modulate brain function in the target regions, and provides mixed evidence on the presence and absence  warrants the conduct of more systematic work to determine the efficacy of rEEG and rtfMRI-based neurofeedback.As discussed above, there is a growing hope that neuromodulation can play a role in the daily practice of addiction medicine. However, the lack of rigorous designs does not provide strong enough evidence to give a green light for clinical use. With frequent negative trials for new pharmacological interventions in addiction medicine, governmental agencies across the world are seriously looking for new hopes for any intervention that can bring positive results in well-powered double-blinded sham/active controlled randomized trials. As the authors of this ISAM-NIG roadmap, we give the following recommendations for future work: Creating international platforms that facilitate consensus on key targets for neuromodulation and outcome measures of efficacy: Addiction neuroscience suffers from the lack of international collaborations based on shared matrix of multilayer targets and outcome measures. We hope that ISAM NIG can bring together a critical mass of expert multidisciplinary scientists across the world to contribute in development of this international consensus.Setting an agreed-upon minimum international standards to produce high quality evidence on the efficacy of neuromodulation in SUD: An overview on the scientific rigor in the published trials on tES/TMS for addiction medicine shows many methodological gaps . New potIncrease the power of neuromodulation experiments: Over 80% of tES/TMS/NFB studies reported 30 or less subjects in each of their arms. Sample sizes can be boosted using multi-site studies with shared protocols with or without shared funding and replication of previous and ongoing studies and trials across distinct laboratories. Larger samples will be instrumental to (i) increase the power to detect existing effects (or lack of), (ii) increase external validity , (iii) make predictive modeling for responders and non-responders possible.We also need to have studies with multi-session interventions and long term follow-up to examine the efficacy in tES/TMS/NF over time, particularly if it increases prolonged abstinence.Strategize research efforts to focus available resources to examine the clinical feasibility/efficacy of neuromodulation: Huge parameter space in almost all areas of neuromodulation prevent providing high quality evidence necessary to inform clinical practice. Pharmaceutical companies are one of the main drivers of drug developments. There is no big company in the field of non-invasive neuromodulation and few new ones for TMS are still considered as "small businesses" (less than 250 employees). Efforts that pool sources of research support, e.g., targeted governmental funds and/or "crowd sourcing"-type collective international efforts may support the development and testing of harmonized neuromodulation protocols/target sites for intervention, in order to provide high quality, well-powered evidence.We reason that incorporating cognitive assessment into clinical practice in addiction treatment requires identification of constructs that predict meaningful clinical outcomes, streamlining of measures for clinical usability while improving retest reliability and ecological validity, and application of technology for remote monitoring and scalability. Translation of neuroimaging measures to clinically meaningful treatment outcomes requires developing imaging biomarkers that have mechanistic, diagnostic, and prognostic value. It also requires testing the cost-effectiveness of introducing brief, targeted brain scans, and deriving quantitative predictors of successful treatment outcome. Application of cognitive training/remediation and neuromodulation requires additional evidence from randomized trials and clear pathways to implementation. These translation efforts need to address all substance-related disorders. To date, most neuroscience studies have focused on alcohol, nicotine, cannabis, and stimulants, whereas opioids have been underrepresented. The promise of translational neuroscience will only be fulfilled if we can provide novel and effective solutions to pervasive addiction problems, for example, the current opioid crisis. Translation efforts should also factor in the heterogeneity of SUD populations in terms of principal drug of choice, patterns of polysubstance use and psychiatric comorbidities. In this regard, assessment and intervention protocols need to advance towards personalized approaches, by capitalizing on advanced machine learning applications.Cognitive assessments and neuroimaging methods can elucidate mechanistic multi-level targets (biomarkers) with neural/cognitive/behavioral levels for neuroscience-informed individualized interventions Figure 4All authors have contributed in design and preparation of the manuscript. RH, RB, AV-G, VL, VM, DP, and HE created the first draft of assessment, imaging, training, and neuromodulation sections, respectively. AV-G and HE integrated all feedbacks from authors. All authors have agreed on the final manuscript before submission.AV-G is supported by Australian Medical Research Future Fund Fellowship (MRF1141214). DM is supported by NIH R01DA039903. MB receives support from NIH R01AA023667. DLP is supported by the Office of Research and Development, Clinical Science Research and Development (CSR&D), Department of Veterans Affairs, Career Development Award—2 (1IK2CX001510-01). SJM was supported by NIH K01DA037452.AB has received research project funding from the MRC, CSO, Schering-Plough, Merck Serono, Lundbeck, and Indivior. ST has received unrestricted educational grants from Indivior, Lundbeck Foundation, and Merck Serono.The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Organic electronic materials have been considered for a wide-range of technological applications. More recently these organic (semi)conductors  have received increasing attention as materials for bioelectronic applications. Biological tissues typically comprise soft, elastic, carbon-based macromolecules and polymers, and communication in these biological systems is usually mediated via mixed electronic and ionic conduction. In contrast to hard inorganic semiconductors, whose primary charge carriers are electrons and holes, organic (semi)conductors uniquely match the mechanical and conduction properties of biotic tissue. Here, we review the biocompatibility of organic electronic materials and their implementation in bioelectronic applications. Bioelectronic devices can already be found in many applications in the medical sector. Indeed, medical electronic devices are now a mature technology. Examples include deep-brain stimulations to treat Parkinson disease , neural While electronics such as sensors and actuators are a mature technology, the main challenge for bioelectronics remains in creating a stable communication pathway between the nervous system and electronic devices. The most common materials currently used to interface between biological tissue and conventional inorganic electronic materials are hydrogels driven by their low Young’s modulus of elasticity and electrical conductivity . HoweverA promising new strategy, however, is to take advantage of the unique properties of organic semiconductors ,14. ThisCritical to the success of bioelectronics is reducing the immune response of an organism to the external device. Ideally, an implant is biologically inert and does not activate an immunological response, but allows target cells to integrate with the bioelectronic application. If the bioelectronic device elicits an immunological response, the device may become encapsulated within fibrous tissue, compromising or seriously disrupting the interface between device and neural tissue. Therefore, before building an implantable device, the biocompatibility of each component needs to be tested. Here, we review the types of biocompatibility tests that are frequently used, the outcome of these tests for various organic semiconductors, and identify classes of organic semiconductors that are of interest to bioelectronic applications.In addition to electrical and mechanical properties, biocompatibility is essential for bioelectronic devices. However, biocompatibility is not uniquely defined and a biomaterial can elicit different responses depending on the local tissue environment. As such, ubiquitous materials that are completely biocompatible in all biological environments remain a theoretical concept. Consequently, the term ‘biocompatibility’ should only be used in the context of the material’s application environment. Indeed, Spector et al. define ‘biocompatibility’ as ‘a condition met by a biomaterial or medical device usually based on the tissue response elicited by an implant in an animal model’ . NeverthTesting for these responses can take place in in vitro, ex vivo, or in vivo environments, however ethical and financial constraints often dictate the use of in vitro cell culture systems during initial stages of testing new materials or devices. In vitro experiments allow for the assessment of the material’s toxicity to cells, cell adhesion, cell activation, cell death, structural stability and preservation of electronic functionality of the biomaterial in cell culture media at 37 °C. Testing for functionality depends on the biomaterial’s intended purpose. For example, testing could involve simple conductivity measurements before and after culture media exposure or testing the device while immersed in cell culture media without exposure to living tissue .-Toxic: biomaterial has adverse effects on surrounding tissue e.g., cell death, immunological response, organ failure and inflammation.-Bioinert: non-toxic, biologically inactive. The material has no or minimal interaction with the living host. However, an adverse response may still occur as fibrous tissue may encapsulate the device, thus loosening and then severing the interface of the device with target cells resulting in device failure.-Bioactive: material is non-toxic and biologically active. The device forms an intimate connection with the host tissue.-Bioresorbable: non-toxic material dissolves in the host tissue. The bio-electronic device only functions temporarily. The surrounding host tissue can eventually replace the synthetic device.Implantation of a bioelectronic device inserted in a living host can interact with tissue in four ways :-Toxic: In vitro assays in the field of organic bioelectronics are often conducted over an ‘acute’ period of up to 10 days . In contIn vitro cytotoxicity tests can be categorised into three types of assay: direct contact, agar diffusion, and extract dilution . While al-lysine, poly-d-lysine and poly-l-ornithine, as depicted in l-lysine is digested by certain cell types, while poly-d-lysine is less easily digested but still prone to adhesion failure  squaraine (a squaraine-based organic semiconductor), because it spontaneously forms a highly textured surface even when mixed with another semiconductor, e.g., phenyl-C61-butyric-acid-methyl ester (PCBM) benzo[rst]pentaphene-5,10-dione mimics red photoreceptors . While P2 [A P3HT-based artificial retina was demonstrated to restore light sensitivity in blind rats ,85. Simi2 . The tec2 . Hence, Conducting polymers such as PPy have the potential to improve nerve growth and guidance, which is crucial for nerve regeneration applications  and is essential for neural integration with implants. Micropatterning a PPy-based electrode can significantly influence the direction or polarisation of axon growth  without Indeed, Schwann cell migration and neurite extension from dorsal root ganglions were more proliferative on a PPy film compared to a glass substrate (control) . During In addition to the general promotion of cell growth, the targeted regeneration of specific tissue aids recovery from injury where certain tissue were destroyed. For example, to bridge a nerve gap, it is important that nerve cells (rather than only fibroblast cells) proliferate. Such targeted regeneration can be achieved using a 3,4-ethylenedioxythiophene (EDOT) based conducting polymer, which displayed high resistance to nonspecific cell binding while tissue specific neurite outgrowth was effectively enhanced (124% enhancement) . These cA combination of both electrical and chemical (neurotrophic growth factors) stimulation is emerging as a preferred approach to improve neuron extension/growth . For exaOther than direct electrical stimulation, organic semiconductors can also be used to control the release of neurotrophic growth factors. For example, PPy doped with p-toluene sulphonate (PPy-pTS) was embedded with NT3. The rate of NT3 release from the PPy-pTS film could be increased by electrical stimulation . Consequ−5 nmol/s when it was switched off.The controlled delivery of biochemical agonists or antagonists would be of great advantage in therapies that require local drug delivery of small quantities at specific times . Second Another approach to drug delivery takes advantage of the structural changes that conducting polymers, such as PPy, undergo during redox reactions. The doped polymer can be electrically switched between the oxidised and reduced state, which is accompanied by the movement of hydrated ions in and out of the film . The eleThe compatibility of organic electronic materials with enzymes and other sensing elements has led to an increase in biosensing-related research activity in recent years . While bThe field of biomaterials and tissue engineering are already accustomed to using polymeric materials due to their favourable mechanical properties and biocompatibility. On the other hand, electronics are largely based on inorganic materials that are mechanically incompatible with biotic tissue and often illicit cellular and immunological responses that can be either cytotoxic or bioinert in nature. Organic semiconductors have emerged as a class of material that combine the favourable qualities of both the biotic and abiotic world and are currently being applied to various bioelectronic applications including electroactive scaffolds, neurostimulation, nerve cell regeneration/guidance, and drug delivery. While bioelectronic devices based on (semi)conducting polymers have been successfully fabricated, and in many cases show better performance than their inorganic equivalent, a theoretical framework underlying the functional mechanisms is lacking. For example, the mechanisms underlying stimulation of semiconductors with light is not well understood. Electrical stimulation is also largely based on empirical results. Without advanced mechanistic models, device design rules can only be built up through empirical data, which slows down progress. Future challenges also involve long-term clinical studies to demonstrate that organic bioelectronics can provide tangible medical benefits. Organic bioelectronics devices are rapidly developing and hold great promise for next-generation medical technology. The potential benefits for the health sector warrants further study and investment.


Anxiety- and trauma-related disorders are prevalent and debilitating mental illnesses associated with a significant socioeconomic burden. Current treatment approaches often have inadequate therapeutic responses, leading to symptom relapse. Here we review recent preclinical and clinical findings on the potential of cannabinoids as novel therapeutics for regulating fear and anxiety.Evidence from preclinical studies has shown that the non-psychotropic phytocannabinoid cannabidiol and the endocannabinoid anandamide have acute anxiolytic effects and also regulate learned fear by dampening its expression, enhancing its extinction and disrupting its reconsolidation. The findings from the relevant clinical literature are still very preliminary but are nonetheless encouraging.Based on this preclinical evidence, larger-scale placebo-controlled clinical studies are warranted to investigate the effects of cannabidiol in particular as an adjunct to psychological therapy or medication to determine its potential utility for treating anxiety-related disorders in the future. Anxiety- and trauma-related disorders are the most common psychiatric diseases and are associated with inadequate treatment options and thus high social and economic costs. Psychological treatments are often limited or temporary in their effectiveness, while medications can lack efficacy or have unwanted side effects in a considerable number of patients. Psychological therapies can also be combined with medications to enhance treatment synergistically, but some medications can interfere with these therapies. Better options are therefore urgently needed for treating these disorders .With the decriminalization of cannabis, availability of cannabis-derived chemicals (i.e. cannabinoids), and anecdotal evidence for the anxiolytic potential of cannabinoids all becoming ever more widespread, it is important to take stock of the empirical evidence to determine if cannabinoids can live up to their hype as an option for treating anxiety-related disorders in the future. In this narrative review, we begin by describing these disorders and the current therapeutic approaches used in their treatment. We then review the preclinical and clinical studies that have investigated cannabinoid regulation of fear and anxiety. We conclude by outlining future directions for driving forward this promising avenue of research.Anxiety and fear are emotional responses that occur in anticipation of potential threat or when facing imminent danger, respectively. These responses are adaptive when they occur appropriately in response to relevant aversive stimuli, but they become maladaptive when expressed inappropriately under benign conditions and can lead to the development of anxiety- and trauma-related disorders . The anxAnxiety-related disorders are treated using psychological therapies or/and medications. The various psychological approaches include cognitive behavioural therapy, exposure therapy, cognitive processing therapy and eye desensitization reprocessing, with the aim of reducing avoidance behaviour and distress •, 7. SelWhile psychological and pharmacological therapies are effective , 8, bothCannabis sativa is one of the oldest plants known for its recreational and purported medicinal properties. It consists of more than 400 chemicals known collectively as phytocannabinoids, over 100 of which are pharmacologically active. The psychoactive delta-9-tetrahydrocannabinol (THC) and the non-psychoactive cannabidiol (CBD) are the most abundant phytocannabinoids and are present in different ratios depending on the plant strain. Other phytocannabinoids that have been less well studied to date include tetrahydrocannabivarin, cannabigerol, cannabichromene and cannabicyclol. The isolation of phytocannabinoids led to the identification of the biological targets by which they exert their effects, including the cannabinoid type 1 (CB1) and type 2 (CB2) receptors. The discovery of endogenous ligands for these receptors, lipid messengers known as endocannabinoids, followed, and the best studied of these to date have been anandamide and 2-arachidonoylglycerol (2-AG) [l (2-AG) •.Cannabinoids have attracted considerable interest as candidate therapeutics for a range of neurological and psychiatric disorders due to the ubiquitous nature of endocannabinoid signalling and CB1 receptor expression throughout the brain , 13. CB1Although recreational cannabis use is rife worldwide, it can be associated with anxiety symptoms acutely . In termStudies using preclinical models of relevance to anxiety-related disorders characterized by abnormally strong and persistent fear memory  have shown that CBD also regulates learned fear and its inhibition in different ways. During fear conditioning, a cue or context is paired with a noxious stimulus, resulting in the consolidation of an associative fear memory. Later cue presentation or context re-exposure alone initially results in conditioned fear responding and can also destabilize the memory trace, requiring its reconsolidation to maintain or update the fear memory. Repeatedly presenting the cue or prolonged context re-exposure also reduces fear responding through an inhibitory learning process known as extinction, which competes with the original memory to suppress fear responding and also forms the theoretical basis of exposure therapy. Reducing conditioned fear responding, disrupting reconsolidation and enhancing extinction are all potential strategies for acute or lasting symptom reduction in phobias and PTSD , 25.Acute systemic CBD treatment or infusion of CBD into discrete areas of the fear circuit before or after conditioning reduces fear memory encoding –29, althGiven the wealth of preclinical evidence for the anxiolytic potential of CBD, it is perhaps not surprising that case reports and small-scale studies examining its effects in a range of anxiety-related disorders have recently emerged. Overall, their findings have indicated that CBD treatment provides symptom relief in these disorders –48. HoweA number of pharmacological mechanisms underpin the potential therapeutic effects of CBD generally , but itsIn contrast to the acute anxiolytic effects of CBD, its enhancement of extinction and disruption of fear memory consolidation and reconsolidation involve cannabinoid receptors. CBD-induced disruption of consolidation is blocked by CB1 and CB2 receptor antagonists infused centrally . DisruptAs alluded to above, endocannabinoid signalling involves endocannabinoid activation of cannabinoid receptors and other non-cannabinoid targets. 2-AG and anandamide are the best characterized endocannabinoids, and they have differing affinities for these targets. 2-AG acts as a full agonist at CB1 and CB2 receptors, while anandamide has lower affinity for cannabinoid receptors but acts as a full agonist at TRPV1 receptors •. EndocaEndocannabinoid signalling is thus ideally positioned to modulate neuronal activity and synaptic plasticity in the fear and anxiety circuitry. Moreover, various gene variants associated with endocannabinoid transmission  have been linked to anxiety-related disorders ••, 62. PIn terms of the cannabinoid receptor-dependent effects of CBD on learned fear regulation described above, CBD increases anandamide levels by inhibiting its transporter-mediated reuptake and degradation by FAAH . CBD alsCB1 receptor agonists can have both anxiolytic and anxiogenic effects, depending on the dose, route of administration, differences in CB1 receptor sensitivity in different brain areas and the aversive nature of the behavioural testing paradigm used . As is tElevating anandamide levels systemically or centrally via the pharmacological inhibition of FAAH is well known to produce anxiolysis, particularly under more aversive conditions . In contIn terms of endocannabinoid regulation of learned fear processing, a seminal study by Marsicano et al. (2003) provided compelling evidence that endocannabinoid signalling via CB1 receptors is crucial for fear extinction. CB1 receptor-deficient mice, or wild-type controls given a CB1 receptor antagonist, showed impaired fear extinction. Endocannabinoid levels were found to be elevated by extinction and also played a crucial role in modulating synaptic plasticity in the fear circuit in a CB1 receptor-dependent manner . SubsequEndocannabinoid signalling has also been implicated in the consolidation and reconsolidation of fear memory. Inhibiting FAAH or MAGL to elevate anandamide or 2-AG levels was shown to enhance fear memory consolidation , 93, whiThe evidence reviewed above demonstrates the potential utility of the phytocannabinoid cannabidiol and pharmacological inhibitors of FAAH, to elevate levels of the endocannabinoid anandamide, for the treatment of anxiety-related disorders in the future. Such cannabinoid-related medicines could be used in various ways to treat these disorders. Given their acute anxiolytic effects, cannabidiol and FAAH inhibitors could be used as adjuncts to first-line SSRI or SNRI treatment, which have a delayed therapeutic response. Such drugs could be an improvement over benzodiazepines, which have abuse liability, a less favourable side effect profile and can interfere with extinction, which forms the theoretical basis for exposure therapy used in the psychological treatment of certain anxiety-related disorders , 10. In The effects of these cannabinoids in other paradigms or measures of learned fear, and its return after extinction, should be characterized to determine if their reported anxiolytic effects are enduring and more widely applicable , 89, 113At the outset, we noted that the availability of phytocannabinoids and their use for self-medication in various anxiety-related disorders have recently become more commonplace. The anxiogenic effects linked to recreational cannabis use  likely i


Posttraumatic stress disorder is a chronic and debilitating psychiatric disorderwith a complex clinical presentation. The last two decades have seen aproliferation of literature on the neurobiological mechanisms subservingaffective processing in posttraumatic stress disorder. The current review willsummarize the neuroimaging results of the most common experimental designs usedto elucidate the affective signature of posttraumatic stress disorder. From thissummary, we will provide a heuristic to organize the various paradigms discussedand report neural patterns of activations using this heuristic as a framework.Next, we will compare these results to the traditional functional neurocircuitrymodel of posttraumatic stress disorder and discuss biological and analyticvariables which may account for the heterogeneity within this literature. Wehope that this approach may elucidate the role of experimental parameters ininfluencing neuroimaging findings. It is estimated that 6.8%of individuals in the general population will meet criteria for PTSD;4 however, this rate substantially increases in populations with greater trauma exposure.5 For example, a study conducted by the Congressional Budget Office6 found that 21% of individuals from overseas contingencies operations (OCO) inIraq and Afghanistan met criteria for PTSD. Furthermore, the Veterans HealthAdministration’s average cost of treating OCO veterans with a PTSD diagnosis wasapproximately four to six times greater than those not carrying the same diagnosis.6 Despite the prevalence and substantial burden, the neurobiology andconcomitant neuropharmacological treatments for PTSD are not well understood. Assuch, there is an increasing need to identify the neural pathogenesis of thisdisorder.Posttraumatic stress disorder (PTSD) is a debilitating psychiatric condition whichdevelops due to the impediment of recovery after the experience of a traumaticevent. Currently, PTSD is viewed as having a complex and heterogeneous clinicalpresentation, spanning four symptom clusters: (1) intrusive memories, distressingdreams, or flashbacks; (2) persistent avoidance of trauma reminders; (3) negativechanges in thoughts and mood; and (4) heightened arousal reactivity.7 which were historically viewed as the defining feature of PTSD.9 Also known as “symptomprovocation” paradigms, these studies focused on affective processes and aimed toelicit neural activity in response to trauma-related reminders, such as idiographictraumatic scripts, images, and sounds. In addition to findings from non-human animalstudies, the results of symptom provocation paradigms put forth a prevailing andelegant functional neurocircuitry model (FNM) of PTSD first proposed by Rauch et al.7 The FNM views PTSD symptomology through the lens of a fear-conditioningframework. Specifically, it was contended that the amygdala is hyperactivated inindividuals with PTSD, contributing to heightened processing of fearful andthreatening stimuli. Next, the medial prefrontal cortex (mPFC), including theanterior cingulate cortex (ACC), subcallosal cortex, and medial frontal gyrus, arefound to be hypoactive in individuals with PTSD, resulting in inappropriatepersistent fear of trauma and non-trauma-related stimuli. Finally, the hippocampusis proposed to functional abnormally in individuals with PTSD, leading to difficultywith adaptive fear learning and extinction.10One approach in understanding the neurobiology of PTSD has been through functionalneuroimaging techniques. Indeed, the last two decades have seen a rapid growth inthe utilization of functional magnetic resonance imaging (fMRI), positron emissiontomography (PET), and single-photon emission computed tomography (SPECT) in theneurobiological inquiry of PTSD. Commonly, these functional techniques employparadigms designed to elicit re-experiencing symptoms,11 When applied to the neurobiology underscoring the clinical manifestation ofPTSD, Patel et al.12 contend that deficits in the central executive network, specifically that ofthe dorsolateral PFC (dlPFC) and lateral areas of the parietal lobe, areunderutilized in individuals with PTSD, whereas the precuneus is reliably overrecruited. In contrast to these findings, Patel et al.’s assert that the saliencenetwork exhibits greater activation in individuals with PTSD, specifically in theanterior insula and dorsal ACC. Finally, the default mode network, specifically themPFC, posterior cingulate cortex, posterior inferior parietal lobule, and leftparahippocampal gyrus were less activated in individuals with PTSD. Althoughfindings from their meta-analysis largely support the triple network model, theauthors note that there were inconsistent findings with respect to thedirectionality of activation due to selection of comparison group, as well asreliable clusters of neural activation which were found outside of the anatomicaldemarcation of the central executive, salience, and default mode networks.12 Another compelling neurobiological model of PTSD is that of the dissociativesubtype, first put forth by Bremner et al.13 In their neurobiological review of this model, Lanius et al.14 found that individuals with PTSD with chronic dissociation—as characterizedby states of detachment, depersonalization, derealization, and subjective distancefrom their emotional experiences—contain unique neurobiological features, which canbe distinguished from the non-dissociative sub-type of PTSD. Specifically, thedissociative subtype of PTSD was found to have a unique neural manifestation, asindicated by the overmodulation of midline prefrontal, dACC, and limbic regions ofthe brain.14Although the FNM has reigned predominate as the most referenced neurobiological modelof PTSD, several other salient models should be noted. The triple network modelproposes aberrant neuronal functioning of the central executive, salience, anddefault mode networks, which may lead to symptoms of multiple psychopathologies.15 conducted a meta-analysis of 19 symptom provocation studies in individualswith PTSD. Their results provided partial support for the traditional neurocircuitrymodel, such that when comparing trauma-related stimuli to the control condition, individuals with PTSD exhibited significantly greateractivation in the bilateral amygdala, mid-line pregenual and retrosplenial cortices,as well as the occipital and angular gyri. However, support for the FNM of PTSD wasnot found when Satory et al.15 compared patterns of activation to trauma-related stimuli between individualswith PTSD and a trauma exposed control group (TEC). Instead, this between-subjectcontrast revealed that individuals with PTSD demonstrated greater activation of themid-line retrosplenial cortex and precuneus in response to trauma-related stimuli.In a similar meta-analysis of 12 symptom provocation studies, Hayes et al.16 found that when comparing trauma-related stimuli to a neutral condition,individuals with PTSD demonstrated greater mid and dorsal ACC activation relative toa mixed control group ), which is consistent with the FNM; however, they also found hypoactivation ofthe precuneus. Finally, Ramage et al.17 conducted a meta-analysis of eight symptom provocation paradigms and foundthat relative to a mixed control group, individuals with PTSD had greater activationof the mid and posterior cingulate, as well as the precuneus. Taken together, theresults of these meta-analyses have led to the growing supposition that the FNM, astested by symptom provocation paradigms, may not fully represent the complexneurobiology underlying disrupted affective processing in PTSD.The traditional FNM has served as a crucial first step in understanding theneurobiology sub-serving anomalous affective processing in PTSD. However, theresults of recent symptom provocation studies are inconsistent, thus suggesting thatFNM may underrepresent the neurobiological complexity of PTSD. For example, Sartory et al.18 indicated theuse of a diverse set of experimental paradigms, such as affective priming, backwardmasking, and tasks that employ non-trauma-related emotion stimuli. To date, only onestudy has reviewed the effect of affective paradigm type on neural activity inindividuals with PTSD, though the authors selectively focused on the neuralsignature of symptom provocation studies and combined all other affective tasks withcognitive paradigms.16 As such, the first aim of this selective review is to identify task-relatedfMRI paradigms commonly used in studies of affective processing in individuals withPTSD. Next, we will classify these paradigms into a useful heuristic based onpsychological conceptual principles, similarity of stimuli used, and fMRI taskmethodology. We then briefly describe the unifying principles of each categorywithin the classification system, the experimental aim of the paradigm category andcommon methodological structure of these paradigms. Using this framework as a guide,we summarize the common and distinct patterns of neural activity that emerged withineach paradigm classification. Considering its importance and proliferation in theneurobiological literature, we then compare these findings to the traditional FNM.10 Finally, we speak to several factors that may contribute to the heterogeneityof findings within the affective processing PTSD neuroimaging literature. Thisreview selectively focuses on neuroimaging studies of affective processing conductedin adult individuals with PTSD and does not include neuroimaging literature producedfrom cognitive tasks which employ affective stimuli . Thereader is referred to excellent comprehensive systematic reviews that have beenrecently published,9 as well as meta-analyses focusing on cognitive processing of affective stimuli,16 studies of symptom provocation,17 the neural signature oftraumatic event type,18 and the effect of traumatic brain injury (TBI) on emotional and cognitive processing.19In an attempt to expand beyond the FNM, studies of affective processing in PTSD havenow been tested with a range of fMRI paradigms. For example, a review of recentneuroimaging meta-analyses focusing on affective processing in adult individualswith PTSD1519 Of these meta-analyses,one was excluded as it examined the neural circuity of PTSD with and withoutmild traumatic brain injury.19 The remaining meta-analyses yielded 99 individual neuroimaging studies,of which 26 were redundant and removed, leaving 73 studies to review based onthe following features: imaging modality ; targetsamples ; comparisoncontrol group ;criterion A traumatic event type ;paradigm description and category ; whole brain versus region ofinterest (ROI) analysis; hemodynamic response function ; and multiple comparison correction . Twenty-eight individual studies were eligible for inclusion, whereas 47 were deemed inappropriate for the scope of thisreview for the following reasons: fMRI paradigms were designed to assesscognitive functioning  using affectivestimuli;21 the samples included in the study were not relevant to thecurrent review, such as adolescents with PTSD22 or the dissociative PTSD subtype only;23 the study assessed processing of physical pain as affective stimuli;24 the fMRI analyses were strictly correlational in nature;25 or the analyses were related to functional connectivity and not generallinear models of task-related data.23 It should be noted that individual studies without standard comparisoncontrol groups  were included; however, this was notated inresults tables . Finally, one article which met our criteria was included, as per theapropos suggestion of a reviewer,26 rendering a total of 29 studies included in the current review.Using keywords “PTSD,” “neuroimaging,” “fMRI,” “PET,” “SPECT,” “affect,” and“emotion,” a literature search was conducted in PubMed, PsychInfo, and GoogleScholar for neuroimaging studies of affective processing in adults with PTSDbetween the months of November and January of 2017 in order to identifycomprehensive meta-analyses of affective processing in individuals with PTSD ascompared to a control group . This search yielded six meta-analyses conducted between 2012 andJanuary of 2017.8 Within this classification, two distinct types of stimuli are routinelyused: bespoke scripts of the traumatic event2739 and trauma-related images,words, sounds, and smells.4043These paradigms are referred to as symptom provocation, as they were originallytheorized to be key in producing re-experiencing symptoms in individuals with PTSD.2739  did not have the full capacityto reproduce uniquely stressful elements of an individual’s traumaticexperience. The structure of script-driven imagery paradigms is largelystandardized with respect to paradigm structure. Generally speaking,participants with PTSD are asked to describe a traumatic experience in as muchsensory detail as possible. These descriptions are then condensed into a 30 to40 s personalized script written in the second person, present tense. Typically,at least three script conditions are utilized in these paradigms: (1) anegative, traumatic experience; (2) a neutral non-traumatic every dayexperience; and (3) a baseline or recovery period. All scripts are audiotaped ina neutral voice and played back to each participant during a neuroimagingacquisition protocol. Procedurally, participants are typically instructed tolisten carefully as their script is being read over the course of 30 s . Next, they are then encouraged to recall as many sensory detailsthat were associated with the traumatic event over the course of the next 30 s. Next, participants enter a rest period for 120 s andinstructed to “let go” of the traumatic memory .Script-driven imagery paradigms are the most commonly used fMRI paradigms in theneurobiological study of affective processing in PTSD2739 see . Theset4043 . However, recent research hassuggested that individuals with PTSD may exhibit an over activated mid-line ACCwhen compared to control participants while processing trauma-related stimuli.15Relative to script-driven imagery tasks, paradigms which employ trauma-relatedstimuli are the next most commonly utilized experimental approach to studyingaffective processing in individuals with PTSD4043 see . Similar42 whereas others reportedhyperactivation of the amygdala relative to NTC group42 andhypoactivation relative to a mixed control group.36 Several studies under thisclassification demonstrated vmPFC hypoactivation in individuals with PTSDrelative to a mixed control group,3136 whereas some studiesdemonstrated the inverse relationship.36 Similar patterns werefound for the rostral ACC, with studies demonstrating a trend towardshypoactivation relative to comparison groups.38 Relative to other regionsimplicated in the FNM of PTSD, there was a paucity of reported hippocampalfindings under this paradigm classification,40 which is interesting givenhow these paradigms putatively rely on episodic memory.8Results from fMRI experiments using symptom provocation paradigms have beeninconsistent and often contradictory see . With re4448 These paradigms areemployed in order to explore patterns of neural activation related to specificemotion categories , stimuli domain , or a combination of the two . Themost commonly utilized trauma-unrelated emotion stimuli are emotion faces, suchas Ekman faces,49 NimStim standardized facial expressions,50 and images from the International Affective Picture System.51 Typically, these images are presented using a block design, in apseudorandomized order of aversive, neutral, and baseline conditions, as theparticipant passively views the images,48 although apseudo-randomized event-related designs have also been used.46 However,it should be noted that compared to other categories within the frameworkprovided, the overall methodological structure of these paradigms is quitediverse with respect to several factors, such as stimulus selection andpresentation length, control condition, as well as paradigm instruction. Resultsfrom previous literature employing such paradigms suggest that we would find aheterogenous pattern of neural activation within this class of studies; however,a recent review of the PFC role in emotion processing of such studies wouldsuggest that the vmPFC would be hypoactivated in individuals with PTSD ascompared to control participants.52This classification of paradigms is referred to as conscious trauma-unrelated, asthey employ stimuli taken from standardized stimulus sets and are notnecessarily related to the traumatic event and are processedconsciously.47 and NTC participants48  at asubliminal level , followed by the rating of a neutral targetstimulus  presented at a supraliminal level . Backwards masking paradigms test the phenomenon whereby the visibilityof a target or primary stimulus is influenced by the presentation of a secondarystimulus.66 Within the affective processing PTSD literature, backwardmasking tasks typically present an affective visual stimulus of interest  briefly , which is followed withinmilliseconds by another visual stimulus , whicheffectively “masks” the effect of seeing the primary stimulus. The generalmethodological structure of unconscious presentation paradigms is quitehomogenous and typically only varies with respect to the selection of stimulusused for the primary or secondary target. Neuroimaging research conducted inunconscious processing of affective stimuli would suggest that the amygdalawould be consistently overrecruited in individuals with PTSD relative to controlparticipants under this paradigm classification.67Affective priming tasks investigate whether the unconscious evaluation of aprimary stimulus  affects the conscious processing of asubsequent stimulus .5968 . Furthermore, the amygdala isbelieved to be a key member of the salience network, an intrinsic connectivitynetwork responsible for the detection and orientation to both internal, as well asexternal stimuli.11 As such, unconscious presentation paradigms may be particularly effective ateliciting differences in salience detection among individuals with PTSD, as comparedto control participants. Paradigms which fell within the symptom provocationcategory exhibited a pattern of hyperactivation in the dACC and hypoactivation inthe vmPFC in individuals with PTSD  may be correlated with differential chronic stress pathology (CSP) burden,subsequently leading to varied patterns of biological abnormalities.7375 Despite this and often inorder to meet sample size and power requirements, neurobiological studies of PTSDtend to aggregate individuals into “mixed samples” and average CSP across differentindex traumas. Thus, larger study samples of individuals with PTSD may containsubsamples with differential threat intensities, CSP, and thus concomitantbiological alterations. For example, recent research has suggested that CSP may beassociated with functional and structural changes due to differential synapticconnectivity patterns.75 A dual pathology model was proposed, which highlights the possibility thattrauma and stress may be associated with two distinct pathophysiological processes,that is, aminoacid-based pathology (ABP) versus monoamine-based pathology (MBP76). ABP is associated with treatment resistance to monoaminergicantidepressants, deficit in prefrontal and hippocampal gray matter, anddysregulation in glutamate and gamma-aminobutyric acid neurotransmission. Incontrast, MBP is associated with enhanced response to monoaminergic antidepressants,gain in nucleus accumbens and basolateral amygdala gray matter, and dysregulation inserotonin and catecholamines.75 ABP is consistent with glutamate dysregulation and excitotoxicity,precipitating reduction in brain-derived neurotrophic factor (BDNF) and synapticloss in the PFC and hippocampus. Specifically, ABP is hypothesized to disruptglucocorticoid signaling, leading to increased neuronal inflammation, andimpoverished astrocytic uptake of glutamate within the synapsis, resulting inextracellular glutamate and excitotoxicity. Conversely, MBP is thought to be relatedto disruption in norepinephrine and dopamine signaling leading to localized increasein BDNF and synaptic gain in the nucleus accumbens and basolateral amygdala.75 As such, this model suggests that individuals with ABP-based pathology mayhave differential patterns of neuronal firing, as compared to individuals with apredominate MBP-based pathology, thus potentially contributing to the heterogeneityfound in the PTSD neuroimaging literature.The heterogeneity of results found in the aforementioned literature may be compoundedby several biological and analytic factors. One such biological factor is related tothe level of threat intensity associated with the traumatic event. Threat intensityrefers to the propensity of a traumatic occurrence to lead to a lasting stress response.77 For example, Sprooten et al. conducted a meta-analysis on the results ofstudies which employed task-fMRI data in a range of psychiatric disorders  and found that on a region-by-region basis, ROIstudies accounted for the over-representation of the amygdala and caudate nucleusactivation, which was not supported when whole-brain studies were considered. Thesefindings suggested that the a priori selection of a ROI, in addition to theneuroimaging fields’ resistance against publishing negative results, may lead to theover-simplification and over-localization of psychiatric neurobiological models.Future studies exploring the neurobiological underpinnings of PTSD symptomology maychoose to move beyond an ROI approach and use alternative statistical methodologies to explore large-scale distributed sub-corticalto cortical networks.78 For example, multi-voxel pattern analysis techniques allow for neuroimagingdata to be reduced to highly reproducible special patterns of activity through asupervised classification classifier.79With respect to analytic factors, a whole brain versus ROI approach may significantlycontribute to the heterogeneity of findings within this literature. For example,approximately half of the studies included in this selective review used amygdalaROI analyses, of which 83% reported activation. Conversely, only three of theremaining studies which did not employ a ROI analysis reported amygdala activation.Although we contend that ROI analyses are useful for restricting analyses tospecific brain regions and controlling for Type I error by limiting the number ofstatistical tests, this analytic approach is not without limitation.12 conducted two separate meta-analyses in individuals with PTSD relative to TECand NTC groups. The results of their study revealed that those with PTSD exhibitedamygdala hyperactivation relative to NTC and not TEC groups, thus indicating thatthis pattern of activation may be, at least partially, a neural marker of traumaexposure and not pathophysiology of PTSD per se.12 Relatedly, there is variability with respect to selection of a consistentcontrol condition. For example, script-driven symptom provocation studiesdemonstrated the use of a generic neutral and “teeth clenching” neutral38 conditions, aswell as the use of an implicit baseline control condition  when performing statisticalcontrasts.3135The choice of comparison group and contrast condition may be additional analyticfactors contributing to contradictory patterns of neural activity within thisliterature. The selection of a comparison group is often contingent upon paradigmdesign. For example, researchers using a script-driven symptom provocation designoften employ a TEC group, as the nature of the experimental design requires that thecontrol group have exposure to a traumatic event. Whereas other design types, suchas unconscious presentation paradigms, often use comparison groups that are naïve totrauma . To address the relevance of comparison group, Patel et al.8082 That being said, we observed avariety of liberal statistical thresholds when addressing multiple comparisonscorrections. For example, a number of the studies reviewed here did not report acorrection for multiple comparisons , or employed an arbitrary voxel-based inference correction when reporting their findings. Although weacknowledge that several of these studies are exploratory in nature and thereforeamenable to liberal thresholding, we recommend that future confirmatory studiesadhere to current minimal statistical standards.8083Finally, variable statistical thresholding approaches to data analysis may be yetanother analytic factor contributing to divergent neuroimaging results of affectiveprocessing in PTSD. We concede that many of the studies included in this review wereconducted in the nascent stages of the neuroimaging field and before specificguidelines of statistical reporting were specified.sons see , used a A chief limitation of the current review is the availability of studies which met ourcriteria for inclusion and our reliance on studies which were included in recentmeta-analyses. Although our original search criteria identified five meta-analyseswhich met criteria, resulting in 99 eligible studies, further inspection deemednearly half of these ineligible, largely due to the utilization of a cognitiveparadigm structure. As such, we acknowledge that the scope of this review narrowlyfocuses on affective processing paradigms conducted in individuals with PTSD.Relatedly, another limitation of the current review is in our utilization of the FNMas a framework for assessing results of the aforementioned affective studies, as theFNM was formulated upon the results of a multitude of studies which used diversestimuli and a variety of paradigm structures .The neural systems subserving affective processing in individuals with PTSD have beenexamined using several experimental designs over the last two decades. A selectivereview of this literature found that affective tasks coalesce into a usefulheuristic with three categories: symptom provocation, trauma-unrelated emotion, andunconscious presentation. Although neural patterns of activation remainheterogeneous, we did observe that unconscious presentation paradigms were superiorin eliciting amygdala hyperactivation in individuals with PTSD relative to acomparison control group. This finding offers partial support for the FNM of PTSD,though we contend that this model may be lacking in its ability to account for theneurobiological complexity of the disorder. Although several biological and analyticfactors can account for a portion of heterogeneity, future research remainswarranted to advance our understanding of the neurobiological mechanisms governingaffective processing in PTSD. The results of our qualitative review, in addition tothe findings from quantitative meta-analyses containing affective processingstudies, suggest the need for a better understanding of trauma-related, as well asanalytic variables involved in interpreting emerging patterns of neural signal.Further investigations are warranted for analyses which take these factors intogreater consideration with respect to their role in neural alterations associatedwith PTSD.


Glioblastoma (GBM) is the most common and the most malignant primary brain tumor and is characterized by rapid proliferation, invasion into surrounding normal brain tissues, and consequent aberrant vascularization. In these characteristics of GBM, invasive properties are responsible for its recurrence after various therapies. The histomorphological patterns of glioma cell invasion have often been referred to as the “secondary structures of Scherer.” The “secondary structures of Scherer” can be classified mainly into four histological types as (i) perineuronal satellitosis, (ii) perivascular satellitosis, (iii) subpial spread, and (iv) invasion along the white matter tracts. In order to develop therapeutic interventions to mitigate glioma cell migration, it is important to understand the biological mechanism underlying the formation of these secondary structures. The main focus of this review is to examine new molecular pathways based on the histopathological evidence of GBM invasion as major prognostic factors for the high recurrence rate for GBMs. The histopathology-based pharmacological and biological targets for treatment strategies may improve the management of invasive and resistant GBMs. Glioblastoma (GBM) is the most invasive, infiltrative, and lethal brain tumor with high proliferative potential . MalignaDuring neural development, neurons and glia are generated from developmental stage-specific and rapidly-dividing progenitor cells, and then quiescent, multipotent stem cells remain stable throughout adulthood . During Unlike in normal brain development, tumor progenitor and quiescent tumor stem cell populations have yet to be understood in brain tumors . A simil in vitro and in vivo settings [Evidence suggests that the invasiveness of malignant gliomas, which mimic the migration attributes of NSCs, could be therapeutically controlled by modifying the intracellular systems or molecular pathways. Moreover, glioma-derived cancer stem cells (CSCs), which are regarded to be a counterpart of primary NSCs in normal brain, have subsequently been shown to be resistant to chemotherapy  and radisettings . Severalsettings –30.Gliomatosis cerebri (GC) is an extremely rare neoplasm which shows diffuse infiltration of glioma cells within central nervous system including brain as well as spinal cord. Since clinical manifestations are various and focal neurological signs are usually recognized late in the course of the disease, the early recognition of this disease is difficult , 32, andGC has specific histological features, namely, tumor cells (i) that are elongated with diffuse and irregular parenchymal infiltration (without formation of a circumscribed tumor mass), (ii) with perivascular or perineuronal satellitosis, (iii) with subpial spread, and (iv) that infiltrate along myelinated tracts with the preserved neuronal axons . NeoplasUsually, the neoplastic cells in GC do not have much proliferative activity, similar to that of low-grade gliomas , 36. TheMalignant gliomas often consist of two subpopulations of cells, which mutually interact and mutually change, that are characterized by uncontrolled-proliferation and by abnormal migration. This has been termed the “Go or Grow” theory of gliomas . One subThis highly complex phenomenon involving molecular and cellular processes has been extensively studied. The mechanisms mediating uncontrolled-proliferation and abnormal migration of glioma cells have been investigated using glioma cell cultures. For example, the population of nonmotile glioma cells in standard cell culture conditions exhibits decreased intercellular space and high proliferating activity, indicating that the population is undergoing cell growth and division. In contrast, cells cultured on laminin exhibit activate migration, enlargement of the intercellular space, and spreading away from the proliferating growth site . Glioma  in vivo and in vitro differs in several ways. Monolayer cell culture is typically employed for in vitro experiments for many kinds of tumor cells, but employing tumor cell spheroids in a three-dimensional culture is better model to mimic in vivo conditions. A spatiotemporal spheroid analysis of U87 glioma cells showing high invasiveness, using computational and experimental approaches, implicates intrinsic cellular mechanisms of glioma invasion: local cell density, radial oriented cell motion away from the spheroid, and intercellular repulsion dynamics are involved in glioma invasion [Glioma invasioninvasion .Recently, a mathematical model based on the proliferation/migration dichotomy of glioma cells has been applied to investigate why modulatory interventions against glioma vascularization have not been successful at controlling glioma invasion . The stuThe “Go or Grow” potential of gliomas is related to metabolic stress which mediates some neuropeptide-processing enzymes. Reduced expression of carboxypeptidase E (CPE), a neuropeptide-processing enzyme that is induced by environmental stressors such as hypoxia and glucose deprivation, contributes to GBM cell migration and invasion . The stuThe mitotic kinesin, KIF11, is a driver of glioblastoma invasion, proliferation, and self-renewal . InhibitFurther analysis of the cellular, molecular, and genetic processes underlying the “Go or Grow” dichotomy is warranted to elucidate novel therapeutic approaches for glioma invasion.The invasiveness of human malignant brain tumors has been reproduced in several animal models in order to investigate detailed histopathological processes.μm in diameter. Due to their small size, it is difficult to identify ENPs histomorphologically by conventional hematoxylin and eosin staining; therefore they are immunohistochemically using galectin-3 antibody [μm in diameter. The macrotumors are considered to be an advanced stage of the neoplastic growth process, and when induced by ENU, they are used as endogenously produced gliomas for analyses of invasiveness [One useful animal model is N-ethyl-N-nitrosourea- (ENU-) induced rat gliomas. A high incidence of CNS tumors including GBMs has been consistently induced in the offspring of rats treated with a single dose of transplacental ENU , and manantibody . Microtusiveness .α (PDGFRα) mutant and Trp53 loss that may induce self-renewal of neural stem cell and develop diffuse intrinsic pontine glioma (DIPG) recapitulating human DIPG [Genetically engineered animals, one of the powerful tools for studying the biology of neoplasms and oncogene identification, have also been employed as developing mouse glioma models. Genetically engineered mice have been successfully used to investigate tumorigenesis and its progression within an intact living organ as animal models for human neoplasms. Weissenberger et al.  generateman DIPG . The hisAnimal models of human GBMs have been established, including subcutaneous or orthotopic xenograft implantation of GBM cells into immunodeficient mice. Patient-derived orthotopic glioblastoma xenograft models using surgical samples of GBM from patients reproduce the histopathology of human glioblastomas. The advantage of the orthotopic GBM xenograft model, compared to subcutaneous xenograft implantation model, is that implanting GBM cells into their anatomical origin equivalent within a host animal provides a biologically suitable site for glioma-brain interactions and maintains genomic characteristics of original human GBMs. Soeda et al.  establisRecently, induced pluripotent stem (iPS) cells derived from human fibroblasts have been used to reproduce glial tumorigenesis. In vivo transplantation of transformed neural iPS cells produced highly invasive tumors containing undifferentiated stem cells, and this model has been used to screen the effectiveness of anticancer compounds and revealed specific molecules targeting transformed neural iPS cells .Specific molecular parameters, in addition to traditional histopathological analysis, have been used to define tumor classification in the revised 4th edition of the WHO Classification of CNS tumors, published in 2016. Indeed, a large subset of glial tumors is now defined based on diagnostics of isocitrate dehydrogenase (IDH) mutation and 1p/19q codeletion, and histone H3 K27M mutation appears to be a fundamental event in diffuse infiltration of glioma cells in DIPG. As described in this review, currently GC is the only subtype of malignant glioblastoma developing a specific growth pattern. However, careful histomorphological examination is still important since, for example, the neoplastic cells within the GC can provide valuable insight into the mechanisms underlying glioma invasion. Furthermore, for example, morphological features such as “secondary structures of Scherer” are still important as diverse phenotypes of IDH(+) or IDH(-) glioma.Detailed histopathological analysis based on the combination of molecular parameters with traditional analytical methods should be used for evaluating efficacy of targeted therapies against cellular and genetic heterogeneity within the invasive and resistant glioblastoma.