The goal of the study was to demonstrate a hierarchical structure of resting state activity in the healthy brain using a data-driven clustering algorithm.The fuzzy-c-means clustering algorithm was applied to resting state fMRI data in cortical and subcortical gray matter from two groups acquired separately, one of 17 healthy individuals and the second of 21 healthy individuals. Different numbers of clusters and different starting conditions were used. A cluster dispersion measure determined the optimal numbers of clusters. An inner product metric provided a measure of similarity between different clusters. The two cluster result found the task-negative and task-positive systems. The cluster dispersion measure was minimized with seven and eleven clusters. Each of the clusters in the seven and eleven cluster result was associated with either the task-negative or task-positive system. Applying the algorithm to find seven clusters recovered previously described resting state networks, including the default mode network, frontoparietal control network, ventral and dorsal attention networks, somatomotor, visual, and language networks. The language and ventral attention networks had significant subcortical involvement. This parcellation was consistently found in a large majority of algorithm runs under different conditions and was robust to different methods of initialization.The clustering of resting state activity using different optimal numbers of clusters identified resting state networks comparable to previously obtained results. This work reinforces the observation that resting state networks are hierarchically organized. The work of Biswal and colleagues A large scale view of the organization of resting state activity was offered by Fox et al. Although some of these RSNs are well defined, further work is needed to determine the relationships of these networks to each other and to the brain as a whole. Subcortical structures also need to be explored in this context. In a recent study using ICA followed by hierarchical clustering, Doucet et al. In addition to insights on the physiology of the normal brain, a better understanding of the relationships between RSNs and the larger scale organization of the brain could contribute to increased knowledge about various neurological and psychiatric diseases. Resting state fMRI has already provided insights on several diseases a priori information. Using a cluster dispersion measure, we find optimal numbers of clusters and relate these results to the two large scale anticorrelated systems.In the present study, we apply a clustering algorithm to explore the hierarchical organization of resting state activity in cortical and subcortical gray matter. The fuzzy-c-means algorithm The two cluster case is of interest in the context of prior studies that identified task-negative and task-positive systems To determine the optimal numbers of clusters, the clustering algorithm was run for 2–20 clusters. Based on the cluster dispersion metric (Equation 4), 7, 11, and 17 clusters were local minima .Surface maps of the seven clusters that were found using the clustering algorithm and random initialization are shown in The temporal similarity measures (Equation 6) between centroids obtained by the seven cluster result are shown in The data were also clustered into seven clusters using non-random initialization see . The resThe average data of the group of 21 subjects were also clustered into seven clusters using random initialization. The spatial and temporal similarity measures between this group and the group of 17 subjects are shown in The eleven cluster result subdivided some of the seven RSNs . Split RThe average data of the group of 21 subjects were also clustered into eleven clusters using random initialization. The spatial (Equation 5) and temporal similarity measures (Equation 6) between this group and the group of 17 subjects are shown in The temporal similarities (Equation 6) between the centroids of the eleven cluster result are shown in The seventeen cluster result subdivided the RSNs further . As compTo demonstrate a hierarchical relationship between the different numbers of clusters, the two cluster result was compared to the seven and eleven cluster results. When the seven clusters were compared with the two cluster result using the spatial similarity measure (Equation 5) , the DMNThe same pattern of positive and negative inner products was seen when the temporal similarity measure (Equation 6) was used to compare the two and seven cluster centroids . The LANThe eleven cluster result was also compared with the two cluster result . In bothAn additional feature of our analysis is the availability of data on the transition between the two and seven cluster results. Accordingly, details of the transition between two and seven, accompanied by the improvement in the cluster dispersion measure  can idenWe demonstrated a hierarchical organization of RSNs by identifying optimal numbers of clusters and relating the seven and eleven cluster result to the two cluster result. Our two cluster result represents a large scale division of resting state activity that also accommodates the finer divisions at the levels of seven and eleven clusters. The two cluster result identified the task-negative system, which in past studies has been shown to include the DMN, and the task-positive system, which has been shown to include the SMN and the DAN We also showed that this pattern exists among the seven and eleven cluster centroids. As an example, the DMN centroid was positively correlated to those of the FPC and LAN networks but negatively correlated to those of the VAN, SMN, VIS network, and DAN.The hierarchical organization found by our method differed in some respects from that found by Doucet et al. Our inclusion of the FPC network in the task-negative system also contrasted with Power et al. The ability to assign a voxel to more than one network illuminates other findings of interest, such as the distribution of the DAN, FPC, and the DMN in the superior and inferior parietal lobule An important result of our analysis is the relative separation between networks that are strongly associated with one or the two large systems  and networks that are more neutral. In both the seven and eleven cluster results, the LAN network and the VAN were least correlated with the task-positive and task-negative systems. Furthermore, the areas of uncertainty in the seven cluster result were similar to the LAN network, FPC network, and the VAN, and the areas of uncertainty in the eleven cluster result were most similar to FPC2.In principle, our results can be related to the functional role that different networks play in cognition. It is well established that RSNs are related to structural connectivity but this relation is far from one-to-one. For example, regions of cortex like MT that have bidirectional anatomic connections to both visual and parietal cortex tend to cohere much more strongly with parietal than visual regions One interpretation of functional connectivity is that it reflects the history of task co-activation of specific sets of brain regions, i.e., essentially a Hebbian construct, as well as genetic factors One significant difference in our analysis compared to past studies The LAN network found using our method was slightly left lateralized and included regions beyond the traditional language areas. In our eleven network result, the LAN network was roughly divided into a lateral and medial cluster. The lateral language cluster consisted of bilateral cortical regions that incorporated Wernicke’s and Broca’s areas on the left. The medial cluster included the caudate, mesial frontal lobe, and inferior temporal lobe. While the lateral cluster would be fully expected given the long history of lesional and task-based imaging The LAN network was also related to the DMN. There was some spatial overlap between the LAN network and the DMN in temporal areas. This may be attributable to the ability of our clustering method to assign a voxel to more than one cluster. In the eleven cluster result, one of the language cluster centroids was also highly correlated to the DMN. In support of this finding, a task based fMRI study showed that areas of the DMN, including the anterior and posterior cingulate, precuneus, and medial frontal cortex, were modulated by auditory or audiovisual narratives in conjunction with superior temporal cortex The cortical portion of the VAN network was very similar to that found in The SMN also had thalamic involvement of the ventral lateral posterior nuclei and the anterior pulvinar nuclei. Connections between the ventral lateral posterior nuclei and motor and premotor areas have been shown Seven We found that eleven clusters also minimized cluster dispersion. Although this number has not been described previously, the eleven cluster result related to the task-negative and task-positive systems with the same pattern of positive and negative correlations as the seven cluster result. In the eleven cluster result, the FPC network, LAN network, VAN, and SMN were divided into two components each. The functional significance of the division of the FPC network into two components requires further investigation. The LAN network and the VAN were each approximately divided into cortical and subcortical clusters.The division of our SMN in the eleven cluster result contrasts with the dorsal-ventral division in the 17 network parcellation by Yeo et al. a priori knowledge about the networks yielded identical results.In the current study, we also demonstrated the usefulness of the fuzzy-c-means clustering algorithm in exploring resting state activity. In our analysis, the fuzzy-c-means algorithm was able to consistently find seven RSNs in the averaged data of 17 and 21 healthy individuals. Many runs of the algorithm with random initialization provided consistent results, and non-random initialization using a priori selection of regions of interest, the fuzzy-c-means clustering algorithm is data driven and allows one to consider all of the data simultaneously without prior information. Graph methods are also applied on a set of predefined regions of interest. In contrast, independent components analysis is also data driven but requires judgment from the user concerning which components belong to RSNs and which are non-physiological, introducing a possible source of subjectivity. The fuzzy-c-means clustering algorithm is designed to find exactly the number of pre-set clusters. Although we have shown that the fuzzy-c-means algorithm is robust when analyzing a group average, further work needs to be done to evaluate its performance with noisier individual data. Most similar is the method used by Yeo et al. A variety of methods have been used to study resting state BOLD activity, including seed-based methods In the present work, we demonstrate a hierarchical organization of resting state activity using the fuzzy-c-means clustering algorithm. We confirm the functional division of the brain into two large systems and further show how these systems further subdivide in hierarchical fashion. Our analysis also shows the importance of including subcortical structures, since they were involved in many RSNs and comprised significant components of the language and ventral attention networks. Finally, we demonstrated the reliability of the fuzzy-c-means clustering algorithm as a data driven approach for finding RSNs.All participants gave written informed consent prior to taking part in the study as approved by the Washington University Institutional Review Board.Resting state BOLD fMRI data  were obtained in two separate populations. Characteristics of the study populations are given in The BOLD fMRI data were preprocessed according to previously published methods Linear trends across runs were removed voxelwise and the data were spatially smoothed with a 6 mm FWHM Gaussian kernel. The data were low-pass filtered to retain frequencies less than 0.1 Hz. Six movement parameters as well as their temporal derivatives were regressed out of the data on a voxelwise basis. The whole brain signal was regressed out from the data Following preprocessing, frames with excessive head motion were excluded using the DVARS method A mask including cortical and subcortical gray matter and excluding white matter and CSF was created using FreeSurfer . Cortical reconstruction and volume segmentation were performed n points to be clustered, kX for k = 1,…,n, a weighted membership between zero and one to each cluster. It requires a priori the number of clusters, c, and the initial location of the centroid, iV for i = 1,…,c, for each cluster. The starting locations can be chosen randomly or with prior knowledge about the data. The points and centroids are represented as vectors, with each element of the vector representing a dimension of information that can be used for clustering. For n points in the data, the membership of each point indexed by k, to each cluster indexed by i, is computed as:iku is the membership of point kX to cluster i. Euclidean distance was used as the distance metric (dist). The parameter M is set at a value greater than 1 that optimizes the clustering k to each cluster indexed by i, the locations of the centroids are updated asThe fuzzy-c-means clustering algorithm n = 18,611 voxels was represented by its correlation to all other voxels in 18,611-dimensional space. The number of clusters, c was set between 2 and 20.The fuzzy-c-means algorithm was applied to BOLD data averaged over all subjects in each of the two groups. For each subject, a gray matter mask was applied to extract the time course of 18,611 voxels in cortical gray matter, basal ganglia, and thalamus. The Pearson’s correlation was calculated between the timecourses of every pair of voxels, resulting in an 18,611 by 18,611 correlation map. The average correlation maps of subjects for each of the groups were then clustered using the fuzzy-c-means algorithm. In this formulation, each of the The initial points of the centroids were chosen randomly and non-randomly. For random initialization, voxels within a randomly chosen cube of 3 voxels in each dimension were averaged as the starting location of each centroid. Since the initial locations of the centroids can affect the clustering result, all results with random initialization are given as the average of 20 runs of the algorithm. When chosen non-randomly, the voxels within a 5 mm radius sphere around regions of interest were averaged to provide the starting location of each centroid. Using Talairach coordinates CD) measure was used to evaluate the clustering results obtained using different numbers of clusters. This metric was calculated as.A cluster dispersion  was calculated as.In order to objectively classify each of the clusters as one of the resting state networks, an inner product was computed between each cluster’s 18,611 length weight vector and a set of reference weight vectors. This is referred to as spatial similarity. For two weight vectors The seven reference weight vectors were those found using 20 runs of the algorithm with random initialization. The identities of the reference weight vectors were determined based on visual comparison with past studies. When new results were computed with a number of clusters other than seven, a best match assignment was made for each of the new clusters.1V and 2V with d elements indexed by t, temporal similarity (TS) was calculated as.We primarily used spatial similarity in the analysis, since it best corresponds to the visual impression of similarity. However, when classifying a large number of clusters where each cluster included a much smaller number of voxels, temporal similarity was used to determine the identities of the clusters. Temporal similarity was measured using the inner product of the time courses, or centroids, of the compared clusters. For two centroids CU) for a voxel i was calculated as:To determine the uncertainty with which each voxel was classified, the geometric mean of each voxel’s weights was taken, where larger values indicated greater uncertainty and smaller values indicated a high degree of membership to one cluster. The classification uncertainty  DMN, D) VAN, F) VIS network, and G) DAN. It had three subdivisions of the B) FPC network, C) LAN network, and E) SMN.(TIF)Click here for additional data file.Table S1Spatial and temporal inner products between the two cluster result and the clusters between 3 and 7.(DOCX)Click here for additional data file.Table S2Spatial and temporal inner products between incremental changes in the cluster number from 2 to 7.(DOCX)Click here for additional data file.


Central cord syndrome (CCS) is considered the most common incomplete spinal cord injury (SCI). Independent ambulation was achieved in 87-97% in young patients with CCS but no gait analysis studies have been reported before in such pathology. The aim of this study was to analyze the gait characteristics of subjects with CCS and to compare the findings with a healthy age, sex and anthropomorphically matched control group (CG), walking both at a self-selected speed and at the same speed.Twelve CCS patients and a CG of twenty subjects were analyzed. Kinematic data were obtained using a three-dimensional motion analysis system with two scanner units. The CG were asked to walk at two different speeds, at a self-selected speed and at a slower one, similar to the mean gait speed previously registered in the CCS patient group. Temporal, spatial variables and kinematic variables  were compared between the two groups walking at similar speeds.The kinematic parameters were compared when both groups walked at a similar speed, given that there was a significant difference in the self-selected speeds (p < 0.05). Hip abduction and knee flexion at initial contact, as well as minimal knee flexion at stance, were larger in the CCS group (p < 0.05). However, the range of knee and ankle motion in the sagittal plane was greater in the CG group (p < 0.05). The maximal ankle plantar-flexion values in stance phase and at toe off were larger in the CG (p < 0.05).The gait pattern of CCS patients showed a decrease of knee and ankle sagittal ROM during level walking and an increase in hip abduction to increase base of support. The findings of this study help to improve the understanding how CCS affects gait changes in the lower limbs. Incomplete spinal cord injury (SCI), comprising about 30% of cases, is the most frequent form of SCI . The cenThe effect that the level of the lesion has on spasticty during walking has been studied in SCI patients , as haveWalking problems following CCS and other incomplete SCI syndromes have led to a wave of interest in using specific treatments, such as botulinum toxin type A  in combiTwelve patients suffering from CCS participated in the experiments. Their average age was 42.6 ± 17.3 years , height 162 ± 0.1 cm  and weight 68.7 ± 15.6 kg  that included 20 subjects . Their average age was 34.5 ± 9.8 years , height, 167 ± 0.1 cm (range 157-184 cm) and weight 65.9 ± 10.8 kg (range 51-95 kg). All the participants provided informed consent prior to be included in this study and the study design was approved by local ethics committee.Kinematic data were recorded at 200 Hz using a three-dimensional motion analysis system  with two scanner units. Eleven active markers were placed on each lower limb Figures  and 2 foAll CCS patients were asked to walk barefoot along a 10-m long walkway at a self-selected speed while temporal-spatial and kinematic data were recorded. It must be noted that all the kinematic parameters of gait depend on the speed . TherefoFive valid trials were collected for each patient at a self selected speed and for CG at a self selected speed and at slow speed to reduce intrasubject variability. All the subjects were given a 1-minute rest period between trials.For each trial, a single gait cycle corresponding to the patient's cycle when crossing the midpoint of a 10-m walkway was selected to ensure that the gait pattern was free of the influence of the initial acceleration and the final braking. The temporal-spatial variables registered were: gait velocity, stride length, step length, stride time, step time, strides/minute, steps/minute or cadence, and percentage of stance phase duration. The joint motion data included: maximum and minimum value of lower limb joint angles throughout the gait cycle in 3 planes, along with the gait cycle instants of occurrence and the joint range of motion (ROM). Both groups of variables were compared between the two groups, CCS and CG.The data from right and left limbs were averaged. All temporal events were expressed as gait cycle percentages (0-100%), defined between two consecutive heel-strikes of the same limb. The spatial parameters, speed, stride length, and step length were normalised by the subject height ,11.For each subject, each computed parameter was calculated as the average of the values obtained in the five trials considered. A descriptive analysis was made of the clinical and functional variables by calculating the mean and standard deviation of the quantitative variables and the frequencies and percentages of the qualitative variables.The normality distribution was checked for all the variables using the Kolmogorov-Smirnov test. Equality of variances was evaluated by Levene's test. Data were analysed using several one-way ANOVA tests (CCS group/CG group) with p = 0.05. All statistical analyses were performed using SPSS 12.0 .We certify that all applicable institutional and government regulations concerning the ethical use of human volunteers were followed during the course of this research.All patients had a cervical injury and they were classified as ASIA D . The resSignificant differences between both groups were obtained in all of the temporal-spatial parameters when walking at self-selected speed Table . Given tThere were no significant differences in these parameters Table .Considering the average duration of the cycle, the maximal pelvic obliquity arose later in CCS patients than in controls, while the minimum obliquity occurred earlier in the patients. In addition, there was a slight anterior pelvic rotation in the CCS patients that was advanced in the gait cycle Table .The maximal hip flexion during stance was significantly delayed in the group of CCS patients with respect to the control group Figure  and thesThe maximal hip adduction during stance occurred earlier in the CG, while during swing the maximal hip adduction was delayed in the CG Figure . In factThe knee flexion at the initial contact was significantly greater in the patients although the maximal flexion during the stance phase was larger in the CG. However, the minimal knee flexion during swing and stance were larger in the CCS group, while knee flexion at toe off was lower in CCS. It must be noted that the CG reached a greater flexion during swing and they showed higher knee ROM in the sagittal plane Table . In addiThe minimal dorsi-flexion or maximal ankle plantar-flexion during stance, at toe-off and during the swing phase was smaller in the CCS group. Consequently, the ankle flexo-extension ROM was higher in the CG.The maximal value of the ankle plantar-flexion occurred earlier in the CCS patients during stance but not during swing Figure . LikewisThe aim of this study was to objectively and quantitatively analyze and evaluate the gait of patients with CCS using three-dimensional kinematic movement analysis equipment, and to compare them with healthy subjects. This comparison was made at both a self-selected speed and at a matched speed in order to avoid any variation due to velocity. The main findings of this study should serve to define the basic rehabilitation strategies for CCS patients.The results of our study reveal that not only do patients with CCS walk at a slower speed but also, that they display a series of kinematic alterations such as a smaller range of movement in the sagittal plane of the knee, greater abduction of the hip at the initial contact and during the oscillation phase, as well as a diminished range of joint movement in the ankle.Some of these kinematic findings coincide with the data published elsewhere regarding the gait of patients with incomplete SCI ,19, suchIn our patients, the range of knee movement was diminished in the sagittal plane, whereby the knee was more flexed during the support phase and less flexed than in the control group during the oscillation phase. This reduced range of knee flexion has been observed in other studies of patients with paraplegic-spastic gait of diverse aetiology, in which this limitation was proposed to be correlated with the degree of spasticity . The degThe reduced joint movement of the knee and ankle in the sagittal plane is not accompanied by a reduction in the hip, as seen elsewhere . The norFrom a clinical point of view, the data obtained suggest that in patients with CCS, we should preferentially work on lengthening the ischiotibialis muscles and on muscle coordination to try to reduce the knee flexion at initial contact, and not only on strengthening the muscles. Indeed, while some studies indicate that an increase in strength in the lower limbs is related with an improvement in gait , others Likewise, we also recommend stretching the anterior rectus femoris and the Vastus lateralis to help increase knee flexion during the oscillation phase and in general, to improve the range of knee mobility in the sagittal plane .One issue that cannot be overlooked is the walking speed. It has been demonstrated that the speed at which we walk conditions the kinematic variables of our gait . Our patThese findings agree with earlier studies of patients with different neurological diseases such as patients with spastic paraplegia , cervicaSince there are many parameters that can be obtained from gait analysis, it is necessary to take into account the reliability of measurements in different joint planes. In marker based gait analysis, some of these parameters can be obtained with greater precision  than others (such as hip or knee rotation), since a larger movement is measured.There are certain limitations associated with this study, the principal one being the lack of kinetic and electromyographic data. Since we are aware of the importance of such data, we have now introduced the necessary modifications to our equipment so that these parameters can be incorporated in future studies. Despite this limitation, the data regarding gait has been collected from the largest group of CCS patients yet studied. To date, the only study of CCS patients published using a three-dimensional analysis of movement to evaluate the kinematics of gait did not describe the pattern obtained in these patients but rather, it compared these CCS patients walking with the aid of one or two walking sticks to evaluate the improvement in this population . Thus, tWe believe it is difficult to perform studies on this type of population given that there is still no clear consensus regarding the diagnostic criteria. However, a recent review concluded  establisCCS patients experience a decrease of knee and ankle sagittal motion during level walking and an increase of hip abduction. The reduction in the range of motion of these joints cannot be attributed to increased spasticity but rather to other compensatory mechanisms aimed at improving gait stability, and to the neural damage suffered by the patients.The findings of this study help to improve the understanding how CCS affects gait changes in the lower limbs and how to design rehabilitation strategies for their treatment.Written informed consent was obtained from the patient for publication of this research and accompanying images. A copy of the written consent is available for review by the Editor-in chief of this journal.None of the authors of this paper have any conflict of interest in relation to any sources of any kind pertinent to this study. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.AGA contributed to the concept and design, planning of study, analysis and interpretation of the data, drafting and completion of the manuscript. AFC contributed to design, analysis, completion of the manuscript and analysis of the data. EPR contributed to the concept, software development, design and acquisition of the data. SPN contributed to the analysis and acquisition of the data. BCR contributed to the analysis and acquisition of the data. AAE contributed to the software development, analysis and acquisition of the data. All authors read and approved the manuscript to be published.


Given the unique advantages over other imaging techniques, functional near-infrared spectroscopy (fNIRS) holds distinct merits for RSFCdf determination. However, an obstacle that hinders fNIRS from potential RSFCdf investigation is the interference of various global noises in fNIRS data which could bring spurious connectivity at the frequencies unrelated to spontaneous neural activity. In this study, we first quantitatively evaluated the interferences of multiple systemic physiological noises and the motion artifact by using simulated data. We then proposed a functional system dependent and frequency specific analysis method to solve the problem by introducing anatomical priori information on the functional system of interest. Both the simulated and real resting-state fNIRS experiments showed that the proposed method outperforms the traditional one by effectively eliminating the negative effects of the global noises and significantly improving the accuracy of the RSFCdf estimation. The present study thus provides an effective approach to RSFCdf determination for its further potential applications in basic and clinical neurosciences.Accumulating evidence has revealed that the resting-state functional connectivity (RSFC) is frequency specific and functional system dependent. Determination of dominant frequency of RSFC (RSFC Literature has revealed that RSFCdf tends to show a difference between various functional systems. For example, the connectivity in the sensorimotor systems was found to be predominant at a low frequency band, usually below 0.1 Hz  plays an important role in supporting neural communication and brain functional integration df, fNIRS holds distinct merits. First, the high sampling rate of fNIRS avoids aliasing of the high frequency noise to the low frequency spontaneous fluctuations that we are interested in df more accurate. Second, the fNIRS signal represents local brain activity directly below the probes, thus avoid the conductive effect in EEG studies. This property is a desirable property for assessing RSFCdf within a specific functional system. Third, the silent environment of the fNIRS scanning excludes the potential confounding led by MRI scanning noise in RSFCdf evaluation, not only for auditory related systems, but also for higher functional systems such as attention. Additionally, fNIRS measures three types of hemodynamic parameters , and thus provides the possibility of understanding the frequency characteristics of RSFC more comprehensively In recent years, a promising noninvasive imaging technique, functional near-infrared spectroscopy (fNIRS), has been successfully utilized to assess RSFC in a resting-state brain df investigation is the noise interferences. Systemic physiological fluctuations, such as pulsation- and respiration-related fluctuations as well as low frequency vasomotion waves, usually exhibit high covariance across fNIRS measuring channels due to their common vasculature-related origins df analysis due to its relatively wide distribution in spatial domain and complex time-frequency structure.However, an obstacle that hinders fNIRS from potential RSFCdf was quantitatively evaluated. Then a functional system dependent and frequency specific analysis method was formally proposed to eliminate these interferences. The validity of this method is proved by using fNIRS data from both simulation and real experiments.To solve the problem, a novel conception was initially proposed that functional system specific spatial information can be used to reduce the adverse effect of these global noises on the detection of the dominant frequency of RSFC in the functional system. The proposed computational framework consists of three basic parts: (1) construction of a spatio-frequency connectivity matrix, (2) spatially weighted coherence analysis, and (3) determination of dominant frequency of RSFC.x and y at frequency λ.x and y;x and y, respectively:x and y, respectively, and the asterisk indicates the complex conjugate. The coherence coefficient λ and bounded between 0 and 1, where 0 indicates an absence of any linear relationship between x and y, and 1 indicates that x is perfectly related with y in a linear fashion.Several metrics have been employed in previous studies of frequency characteristics of RSFC. Some studies used the cross-correlation coefficient at multiple narrow frequency bands x and any other channel y, the coherence between the two channels at a given frequency λ was defined as y and frequencies λ, a two-dimensional matrix x) and another channel (i.e. y), denoted as λ, denoted as λ. Therefore, the matrix Given a predefined seed channel In the proposed method, we took advantage of a predefined probability map , as discussed in Introduction section, there should be an intense and widespread coherence among all the measurement channels. Such global characteristic of the connectivity map is quite different from the locally distributed template p value was assigned for each To quantify the dominant frequency of RSFC, we proposed a non-parametric procedure to compute the statistical significant of I was set as 0–0.25 Hz as the whole frequency range in which the specificity and sensitivity were assessed. Furthermore, considering the possible effect of the biased threshold selections on the resultant To quantity the accuracy of the For comparison, we also evaluated the performance of the traditional coherence analysis method. In the traditional coherence method, the connectivity within a certain functional system  is directly represented by the coherence between the averaged time courses from two representative ROIs in the system (e.g. the left and right primary motor areas) A series of simulated and real fNIRS experiments were conducted in this study. In general, each set of simulated data Specifically, the components of spontaneous fluctuations were generated using the following model:df determination, a comprehensive systemic physiological noise was simulated at each measuring location k as follows:To evaluate the potential influence of the systemic physiological noises, such as pulsation- and respiration-related oscillations as well as low frequency vasomotion waves, on the RSFCdf determination, the motion artifact To assess the influences of motion artifact on the RSFCIn the proposed method, the spatial template t-map) was obtained based on the general linear model Twenty-one subjects were recruited from Beijing Normal University. Informed consent was obtained before the experiment according to the procedure approved by the Review Board at State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University. All subjects participated in two sessions of fNIRS measurements. The former was 11-min resting state session, and the latter was a sequential bilateral finger tapping task . The simulations were close to the conditions in the real fNIRS experiment at our utmost. The simulated experimental results clearly showed that all types of global noises generated redundant correlations in the frequency band unrelated to spontaneous neural activity and resulted in a low specificity of RSFCdf studies. On one hand, the underpinning theoretical assumption of this method, that the observed hemodynamic signal can be expressed as a linear sum of the spontaneous fluctuations and the systemic physiological terms, is not clearly proved df analysis.In previous fNIRS-based RSFC studies, various methods have been utilized for the general purpose of noise removal; however none of the methods were intensive enough to address the problem of the global interference mentioned above. A simple and widely adopted approach is temporal filtering p<0.05 at group-level, FDR corrected, not presented in the text). Despite slight differences in the two templates, the outputs of the proposed method were quite consistent. Moreover, the spatial template can be appropriately smoothed to further reduce the influence of template estimation error on the final results.As demonstrated by theoretical analysis, the predefined spatial template of the functional system of interest is an important parameter in the proposed method. Thus, its accuracy may have influence on the performance of the proposed method. To assess this potential impact quantitatively, we simulated the template with different levels of position or/and size discrepancy to represent the inaccuracy of the estimated template in the actual experiment. The results showed that the method was robust to the discrepancy of the template at a moderate degree. Furthermore, in the real resting-state fNIRS experiment, we tested two different template generation approaches. The first template was constructed according to the anatomical localization information of each channel, and the second one was made from the task activated result during the motor task , and in the occipital cortex, especially in primary visual and related regions , was at both low (<0.08 Hz) and high (0.17–0.25 Hz) frequencies df in basic and clinical neuroscience. The discrepancies of the preliminary results may have resulted from the slight influences of the strident noise and the direct visual stimulation in the fMRI scanner, and/or an aliasing effect due to the low sampling rate of fMRI; however, the introduction of fNIRS into RSFCdf studies can basically overcome these issues. Moreover, because of the portable and cost-effective features of fNIRS, along with the plainness of the proposed method in this study, the RSFCdf investigation can be largely carried out for both of healthy populations and patients with neurologic and psychiatric disorders in the future.Despite some meaningful findings on the RSFCdf. Similarly to the fNIRS-based RSFCdf analyses, fMRI studies also have suffered from the global distributed physiological interference and motion artifacts df study. Further work should be carried out to test its feasibility in practical.The proposed method also has potential to be adapted for assessing fMRI-based RSFCdf has changed during development, normal aging, or due to neurological or psychiatric illness. However, it seems to be precluded from more complicated situations, such as investigating the frequency of RSFC between different functional systems  Despite the merits mentioned above, it is necessary to point out that the proposed method is effective in the case of the large brain area measurement. To construct the spatial template, the spatial coverage of the probe should comprise both inside and outside of the functional area of interest. If there is no sufficient spatial coverage , the performance of the proposed method will be limited. Fortunately, as the multi-channel measurement fNIRS technology is becoming mature and popular in recent years Text S1Supplemental Information on (DOC)Click here for additional data file.Text S2Data Generation for Simulative Experiments.(DOC)Click here for additional data file.


We examined how the inclusion of a future intention to screen item . A total of 3,638 cases were available for analysis with 914, 838, 956, and 930 in the mail/future intention, mail/no future intention, telephone/future intention, and telephone/no future intention conditions, respectively. False positives were defined as self-reporting being screened among those with no documented history of screening in medical records and false negatives as not self-reporting screening among those with history of screening.Comparing false positive and false negative reporting rates for each specific screening test among the responders at the bivariate level, regardless of mode, there were no statistically significant differences by the presence or absence of a preceding future intention question. When considering all tests combined, the percentage of false negatives within the telephone mode was slightly higher for those with the future intention question . Multivariate models that considered the independent impact of the future intention question and mode, affirmed the results observed at the bivariate level. However, individuals in the telephone arm (compared to mail) were slightly (though not significantly) more likely to report a false positive .It may be that in the context of a questionnaire that is clearly focused on CRC and with specific descriptions of the various CRC screening tests, certain design features such as including intention to screen items or mode of administration will have very little impact on the accuracy of self-reported CRC screening. Large sample surveys such as the Health Information National Trends Survey (HINTS), the Behavioral Risk Factor Surveillance System (BRFSS) Survey, and National Health Information Survey (NHIS) routinely collect self-reported colorectal cancer (CRC) screening information, but the accuracy of the information coming from these important sources remains largely unknown as the scant literature on the accuracy of self-reported CRC screening is equivocal. While some have found consistent over-reporting of CRC screening relative to various criterion or gold standards such as medical records ,2, some after the CRC screening question (“future second”) as compared to the condition where we asked about intentions first (“future first”); in the telephone condition, the odds of reporting were only 28% higher in the “future second” condition than in the “future first” condition. The results suggest that asking about future intentions to get screened before the actual behavior elicits lower - and arguably more truthful - reports of CRC screening, but only in mailed surveys.There is evidence that questionnaire design features such as item wording and context, as well as mode of data collection , can impact the accuracy of all self-reported health behaviors in general and cancer screening behavior in particular ,6. One pAlthough this prior work was among the first to test the effect of asking about future intentions and mode of administration simultaneously in a factorial design and with a community sample , the study had some potentially important limitations. First, whereas past investigations have focused on consistency between self-reports and medical records as the primary measure of accuracy, we only looked at the former in the initial 2008 study as we did not have medical record data with which to compare. We have addressed this limitation by focusing on consistency between CRC self-reports and medical records as the primary measure of accuracy in the present investigation. Second, the earlier study utilized items that did not include complete descriptions of the screening tests, contrary to the recommendations of some ,8. The aIn the current paper, we retain the community and methodological elements of our prior work but focus on consistency between self-reports and medical records as the primary measure of accuracy, drawing on the strengths of the Rochester Epidemiology Project (REP) - the medical record linkage system for health care providers to residents of Olmsted County . We also utilize items more aligned with the manner of question asking in major surveys  that have been tested for reliability and validity. By deploying a more optimal design in the present investigation, we are in a better position to inform the collection of self-reported CRC screening rates in surveys such as the NHIS, BRFSS, and HINTS than we were after the prior investigation.The investigation described herein uses data collected from residents of Olmsted County, Minnesota. With the exception of a higher proportion of the working population employed in the health care industry, population characteristics of Olmsted County are similar to those of the US white population . The RocThe target population was men and women between 49 and 85 years of age who lived in Olmsted County for at least 10 years at the time the sample was drawn in order to minimize the opportunities for screening outside of the REP catchment area. Eligibility status was determined from the REP medical record and administrative data. Potential participants were excluded if there was a diagnosis of colon cancer or a history of genetic syndromes.The primary objective of this research was to test the unique and interactive effects of asking about future intention to get screened for CRC  and survey mode (mail versus telephone) on the accuracy of self-reported CRC screening behavior. The study design used permitted us to assess negative, as well as positive, CRC screening histories and, therefore, the degree of under- and over-reporting across question order and survey mode. Both those with NO history of any CRC screening in the REP and those WITH a history of at least one CRC screening in the REP were purposively sampled at an approximate 2:1 ratio and randomly assigned to the mail or telephone modes. CRC screening tests included fecal occult blood test (FOBT), sigmoidoscopy, colonoscopy, computerized tomographic colonography (CT colonography), and barium enema. Eligible participants were then randomly assigned to one of two question wording conditions within mode where they received the future intention to get screened for CRC either before the CRC screening item or not at all (described below).We modified the format of the NCI CRCS questionnaire developed by Vernon and colleagues that provides CRC screening test descriptions prior to asking questions about test use . For eacSurvey data collection was performed by the Mayo Clinic Survey Research Center (SRC) between November 2010 and April 2012. A multiple contact data collection protocol was deployed for both mail and telephone conditions per the method proposed by Dillman [For those randomly assigned to the telephone mode, the interviewer first completed the interview and then indicated that in order to use the supplied interview data, the respondent would have to fill out a HIPAA Authorization Form (HAF). If the respondent indicated that he or she did not have a copy of the HAF available from the prior mailing, another one was sent the same day of the interview. Calls to attempt an interview were made by trained CRC interviewers at a variety of times of the day  and days of the week (weekdays and weekends). Telephone numbers were attempted up to five times per case and messages were left on answering machines to increase participation. At any point, if a subject expressed a desire not to participate, he or she was not contacted further. All consent and study procedures were approved by the Institutional Review Boards at Mayo Clinic and Olmsted Medical Center.A total of 6,023 and 3,396 eligible participants were assigned to the mail and telephone modes, respectively, and invited to complete the survey. The response proportion was calculated as the number of completions divided by the number of eligible participants using the response rate calculation formula (RR3) set forth by the American Association for Public Opinion Research . A totalSurvey respondents were compared between the four conditions with respect to the sociodemographic information we had available in the REP. These analyses enabled assessment of selection into mode based on differential mode preference after random assignment and to identify any possible confounders that warranted adjustment in the primary analyses. Response rates were compared between modes with a chi-square test. Overall comparisons were performed with chi-square tests (gender and race) and analysis of variance (age). Further, the distribution within each condition was compared to the entire group  using chi-square goodness-of-fit tests for gender and race, and with one-sample t-tests for age, treating the overall distribution as fixed. To determine whether false self-reports of each  or any (any one of those listed) past CRC screening behavior varied by condition, the self-reported percentages were compared by mode and presence or absence of the future intention question using chi-square tests . To evaluate the accuracy of self-reported CRC screening and using information in the REP as the standard, false positives were defined as self-reporting being screened among those with no documented history of screening. False negatives were defined as not self-reporting screening among those with history of screening. The “truth” with respect to history of screening was defined by whether or not there was evidence of past CRC screening in the REP at any time prior to the fielding of the survey or self-reported screening outside of Olmsted County (which would not be available in the REP).Based on the premise that respondents tend to over-report socially desirable health behaviors such as CRC screening and that our manipulations were most likely to impact false positives, logistic regression analysis was used to determine whether or not false positive rates varied by mode of data collection, the presence or absence of the future intentions item, and/or their interaction, adjusting for age, gender, and race. All P values are two sided, and a P value of ≤ 0.05 was regarded as statistically significant. All reported percentages, means, and regression analyses were done using SAS v. 9.3 software .Table Among the screening tests considered, the most common were sigmoidoscopy and colonoscopy. Documented screening rates were significantly higher among responders as compared to non-responders within the mail (86.2% vs 62.1%) and telephone (75.2% vs 55.4%) modes (p < 0.0001 for each). Comparing false positive and false negative reporting rates for each specific screening test among the responders at the bivariate level, within mode (mail or telephone), there were no statistically significant differences by the presence or absence of a preceding future intention question  self-reported screening . Table decrease accuracy when compared to medical records.Going into the present investigation, we had hypothesized that asking about future intentions to get screened for CRC before the question about past screening behavior would increase the accuracy of the latter when compared to medical records. In our earlier study, we found that asking about intention before screening resulted in lower reports of past screening by a rather significant amount . Similarbefore the actual past behavior, they will feel less pressure to misrepresent their past practice of that behavior in a positive light. However, recent studies have found that the accuracy of self-reported CRC screening is unrelated to social desirability [Why our results run counter to what has been observed in the literature is unclear, but it could be due to the role social desirability may or may not play in the accuracy of self-reported CRC screening. The impact of the intention item is premised on the notion that by asking people if they intend to engage in a socially desirable behavior such as CRC screening rability ,15, so oWhy our current results differ so significantly from our own work may be due to the methodological limitations of the latter listed in the introduction, primarily the absence of definitional clarity. It may be that in the context of a questionnaire with specific descriptions of the various CRC screening tests as recommended by Vernon and colleagues , certainAlthough self-reported CRC screening accuracy was not associated with the inclusion of the intention item in our study, it is worth noting that accuracy tended to be higher in the mail administration mode rather than telephone, albeit not statistically significantly. This is consistent with the meta-analysis of the extant research on CRC screening accuracy conducted by Rauscher and colleagues  who founIn conclusion, our experimental findings extend the work on self-reported CRC screening accuracy, generally, and the impact of certain survey design features such as questionnaire layout, item wording, and mode of administration in particular. We found little impact of the intention item and suggestive evidence mailed surveys positively affect accuracy. Future research should continue to identify mechanisms underlying the over-reporting of positive health behaviors, such as CRC screening, and do so with more heterogeneous populations than the one of focus in the present investigation. However, it is possible that CRC screening is not viewed as a positive health behavior along the lines of healthy dieting or exercise and the literature associated with those types of behavior is not germane or translatable to CRC screening. As such, other factors contributing to the over-reports observed with this behavior beyond social desirability need to be explored. Our findings also underscore the importance of offering definitional clarity when asking about complex and potentially confusing cancer screening tests, such as those included in the CRC realm, as well as other areas such as Pap test and mammography. Given the importance of clear and defensible estimates of cancer screening to clinical and health policy experts, coupled with the seemingly contradictory findings to date, continued dedication to finding the optimal manner in which to secure such estimates is paramount.The author’s declare that they have no competing interests.TB, JZ, and TJ made substantial contributions to the conception and design of the study and acquisition of the data. They also, along with SJ and KL, made substantial contributions to the analysis and interpretation of the data. All authors contributed to the drafting of the manuscript, reviewed it, and made important suggested revisions. All authors also approved the final, submitted version of the manuscript. The manuscript has not been published (in full or in part) either in print or on-line and is not under consideration for publication elsewhere.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2288/14/19/prepub


The fund of knowledge regarding the versatility of presentation of MM metastases is still quite incomplete. The recent literature pertaining to the current understanding of the mechanisms underlying two special features of MM metastasis is reviewed. On the one hand, a long disease-free interval (MM dormancy) may occur before the surge of overt metastases. On the other hand, the so-called MM smouldering phenomenon refers to the condition where regional metastases wax and wane for long periods of time on restricted skin regions. It is important to emphasize that local micrometastases often predict sentinel lymph node involvement but may not reflect progression of the primary MM to full-blown visceral metastatic competence. It is likely that a combination of factors impacts the versatile MM metastasic progression. Among the main factors, one has to mention the phenotypic heterogeneity and variability in the phenotype of MM cells, the presence of MM stem cells and MM cells engaged in an amplification proliferation pool, as well as the host immune response, and possibly the induction of a particular stromal structure and vascularity. Limitations in the understanding of the biologic versatility of malignancies including malignant melanoma (MM) have resulted in different definitions of even their most fundamental terms , 2. In sThe evolution of MM metastases is typically the result of tumor progression and their aspects are related to (a) the malignant cell proliferation kinetics, (b) the antigenic differentiation of the cell molecular components, and (c) the release of growth factors influencing the peritumoral stroma including vascularization.On clinical ground, several groups of patients may be identifiable according to the MM evolution. A first group encompasses primary MM remaining localized for months or years (slow growing MM). A second group is formed by MM growing rapidly in a matter of weeks (fast growing MM) . A thirdOn histopathologic ground, the MM growth rate is related to the proliferative activity of its cells. The mitotic rate , 5, the 2, is advocated by the American Joint Committee on Cancer (AJCC) group [The numeration of mitotic figures, being either below or above 1/mmC) group . Unless C) group , 12.The balance between cell proliferation and apoptosis is of paramount importance in the determination of the MM tumorigenic potential . The proThe putative role of MM stem cells is increasingly recognized in the primary MM and its metastases –22. In gMM originating from the skin and subsequently releasing metastases exhibits some pathologic attributes in relation to the host. In its early stage of evolution the neoplasm does not set up any effective and complete immunologic rejection by the host, otherwise any incipient MM would be readily destroyed. In fact, the MM cell phenotype is typically heterogeneous  althoughThe process of metastasis consists of a series of linked, sequential steps. Although some of the steps in this process contain stochastic elements, metastasis as a whole favors the survival and growth of a few subpopulations of cells that preexist within the primary neoplasm. Metastases may have a clonal origin, and different metastases possibly originate from the proliferation of few cells. The outcome of metastasis depends on the interaction of metastatic cells with various host factors. Organ-specific metastases have been demonstrated in a variety of neoplasms and may be specific to a particular site within a given organ. Clonal analysis of human MM revealed that these neoplasms were heterogeneous for metastatic properties and that growth in the environment of specific organs is selective. These findings suggest that systemic physiologic signals are potentially recognized by neoplastic cells, presumably by mechanisms similar to those shared by their normal cell counterparts. A fundamental prerequisite for MM metastases resides in the ability of MM cells to dissociate from the primary MM and to breach a series of sequential structural and functional barriers. The progression of any primary MM and its metastases has to be adaptable to distinct and variable environments in order to survive. In all likelihood, a natural selection of MM cell phenotypes occurs during MM invasion. The same feature operates in every collection of metastatic MM cells lodging at different body sites . Indeed,Any local recurrence at the site of the primary MM rarely develops simultaneously with disseminated disease. MM metastases commonly involve body sites where other cancer metastases are collected, namely the skin, lymph nodes, and lungs.The host defences do not apparently achieve the same efficacy in every tissue. Therefore, it comes about that selective survival of MM cells is possible in some restricted organs and tissues. In addition, the host defences may be altered by immunosuppression . An alteIn a global perspective, the induction of a local micrometastatic process does not ineluctably lead to overt metastases at distance. Indeed, at the onset, the micrometastasis may be destroyed, remain quiescent even for years, or may grow under a positive proliferation-apoptosis balance. Typically, the fate of metastatic MM cells varies in time. Even after a long period of quiescence, overt metastasis may appear . They maMetastasis is defined as a malignant neoplasm arising from a primary or metastatic malignancy without remaining no longer in contiguity with the initial tumor. In the early step of evolution, MM lesions lack competence for metastasis. Indeed, selected metastatic steps depend on (a) the rate of cell production in the primary neoplasm, (b) the number of cells migrating away from the primary site, (c) the number of cells entering a venule or a terminal lymphatic, (d) the number of cells surviving in the blood or lymph vascular pathway, (e) the number of cells escaping from vascular pathway, and (f) the number of cells surviving and replicating at the metastatic site. Any step in the metastatic pathway must ultimately be related, in some way, to the rate of production of the cells in the primary MM , 9, 10.Presence of MM microsatellites is associated with increased overt locoregional metastases –30. It mA fundamental understanding of mechanisms involved in MM metastasis has been improved over the past two decades. Several migration paths for MM micrometastases were identified in the skin. These cells may be found inside some vessel lumina , inserteBy definition, cells in a distant metastatic site have full metastatic competence. Consequently, it seems likely that metastasis from metastasis is a routine event in neoplastic biology. However, the role of the stroma hosting MM metastasis is not harmless because a cardinal property of a malignancy is the ability to grow in the mesenchyme at the primary and secondary sites. Indeed, the premetastatic mesenchyme is noticeably different from the normal. When neoplastic progression is active, MM lesions have both a neoplastic parenchyme and a neoplastic mesenchyme.As the mesenchyme of the distant site is unprepared and may require a long period of neoplastic adaptation prior to significant growth. Thus, metastases may be limited to a single organ or tissue for a certain period of time. Such patterns of spread may reflect the existence of cells only capable of growth in the mesenchyme specific to a given organ or tissue. Common restricted pathways include skin metastases.An eventual lack of metastasis could be explained by a subset of tumors capable of growth in the stroma at the primary site, but incapable of completion of any step in a metastatic pathway, except for invasion and some motility in the dermis. According to such hypothesis invasiveness and metastatic development would not be acquired in concert, but as successive cell adaptations.The interrelations between the host and MM cells are under the influence of a vast array of factors. These events are probably not static, but result from a continuous fluctuating balance between two living systems engaged in natural selection. The changes in time of the combination of different cell processes including MM and its microenvironment may lead to a condition named smouldering MM.The concept of smouldering MM was raised after an extensive study of MM over more than 20 years, emphasizing the way by which established metastatic disease may vary in its evolution . The semThe smouldering MM phenomenon contrasts with the more common synchronized burst of metastatic crops. This latter condition has been particularly observed following excision of a primary MM at a time when the metastatic diseases remained undisclosed. The smouldering MM highlights the fact that tumor progression is not ineluctable. Indeed, the net directionality of MM metastasis early in tumor progression may be toward growth or regression. This may be due to the apoptosis prevalence over proliferation, the versatility of antitumoral immunity, the lack of stromal receptivity, and any defect in angiogenesis. Of note, smouldering inflammation in the neoplasm microenvironment promotes proliferation and survival of malignant cells, angiogenesis, metastasis, subversion of adaptive immunity, as well as response to hormones, and chemotherapeutic agents . This muThe smouldering MM phenomenon probably involves a combination of distinct cell properties related to site-specific MM cell growth, site-specific adhesion molecules, site-specific metastatic cell invasion, and site-specific regulation of metastatic cell growth and regression. Novel concepts regarding early seeding of metastases coupled to parallel progression, self-seeding of primary tumors by circulating neoplastic cells, and the induction of premetastatic niches in distant organs by primary cancers have come to the fore . Such coAny unusually long latency period between the primary MM treatment and metastatic occurrence corresponds to a clinically disease-free condition. It is commonly thought to represent clinical MM dormancy. The relationship between such condition and the cause of MM cell dormancy is complex and probably multifactorial . The proTumoral dormancy and autophagy may be in part correlated. Autophagy is a homeostatic and catabolic process that enables the sequestration and lysosomal degradation of cytoplasmic organelles and proteins. Such process is important for the maintenance of genomic stability and cell survival. Autophagy is a mechanism of stress tolerance that maintains cell viability and possibly leads to tumor dormancy, progression, and therapeutic resistance .Delay of MM metastases is a manifestation suggesting a host defence mechanism or a peculiar nature of nonproliferative MM cells possibly involving MM stem cells. Globally about 40% of patients who develop MM metastases do so more than 5 years after primary treatment. A typical example is the appearance of metastases in the liver, many years after removal of the eye affected by intraocular MM. The disease-free interval before metastases may be as long as 25 years. When metastases from uveal MM develop, they almost always appear first in the liver and often are found only in the liver. This strong tendency to involve the liver early in the course of the disease is not explained on the basis of any anatomic or physiologic factors. The reasons for the long interval from primary treatment to metastases in uveal melanoma are completely unknown. Since the eye has no lymphatic drainage, the MM must have already metastasized prior to the enucleation, and yet a long period of time may elapse before these metastases appear clinically in the liver. The rate of growth of these overt metastases varies considerably once clinically detectable. It is tempting to speculate that these metastatic implants remain dormant for many years because of some intrinsic controlling mechanism of the MM cells themselves or a systemic control by the host. Another example of MM dormancy deals with MM developed from transplant organs in patients placed in immunocompromised condition , 45, 46.The development of MM metastases is not the expression of a single uniform process. Many factors linked to the nature of the neoplastic cells and the reactivity of the host interfere in a complex way. Smouldering MM reflects the individual life of each metastasis confined to a restricted skin territory. The lesions wax and wane in an apparently haphazard and uncoordinated way. MM dormancy refers to a condition where overt metastases appear after an extended lag time. The intervention of metastatic MM stem cells or of metastatic MM cells blocked in the cell cycle of proliferation is possible.The two phenomena, that is, the smouldering and the dorman processes presently described in the MM metastatic progression might in addition possibly occur at the primary site. The smouldering primary MM phenomenon could correspond to the partial MM regression which is a frequent observation. The primary MM dormancy would correspond to a lengthy duration between MM initiation and the early clinical stage of MM duration.These two conditions are worth studying because new therapeutic advances could emerge by stirring up and controlling the smouldering and the dormancy MM phenomena.


Physician prescribing is the most frequent medical intervention with a highest impact on healthcare costs and outcomes. Therefore improving and promoting rational drug use is a great interest. We aimed to assess the effectiveness and cost-effectiveness of two forms of conducting prescribing audit and feedback interventions and a printed educational material intervention in improving physician prescribing.A four-arm randomized trial with economic evaluation will be conducted in Tehran. Three interventions  and a no intervention control arm will be compared. Physicians working in outpatient practices are randomly allocated to one of the four arms using stratified randomized sampling. The interventions are developed based on a review of literature, physician interviews, current experiences in Iran and with theoretical insights from the Theory of Planned Behavior. Effects of the interventions on improving antibiotics and corticosteroids prescribing will be assessed in regression analyses. Cost data will be assessed from a health care provider’s perspective and incremental cost-effectiveness ratios will be calculated.This study will determine the effectiveness and cost-effectiveness of three interventions and allow us to determine the most effective interventions in improving prescribing pattern. If the interventions are cost-effective, they will likely be applied nationwide.Iranian Registry of Clinical Trials Registration Number: IRCT201106086740N1Pharmaceutical Sciences Research Center of TUMS Ethics Committee Registration Number: 90-02-27-07 Over the past decades, new generations of antibiotics, analgesics, corticosteroids and other medicines have been introduced to the pharmaceuticals market. At the same time, health care systems are confronted with a continuing pressure to provide high-quality care in the face of increasing costs and limited financial resources.Due to the rising pharmaceutical expenditures in the world, governments are struggling to keep costs under control -3. ThereChanging prescriber behavior is difficult and may require complex multilayered interventions . Such inAccording to a Cochrane Review, audit and feedback is defined as a summary of health care performance over a specified period of time with or without recommendations for a clinical action . EvidencIn Iran for many years, the problems of irrational drug use have been investigated by academic members of several universities -24. In 1The main objectives of the study are:1) Does the routinely conducted prescribing audit and feedback intervention influence general physicians, pediatricians and infectious disease specialists prescribing behavior in comparison to printed educational materials and no intervention?2) Does a revised audit and feedback intervention improve prescribing behavior compared to the routinely conducted prescribing audit and feedback, printed educational materials and no intervention? At the same time, we evaluated cost-effectiveness of the interventions compared to the control groups.The study design is a four- armed randomized controlled trial with economic evaluation. It includes three different intervention arms and one control arm: routinely conducted audit and feedback, revised audit and feedback, printed educational materials (pamphlets), and a no intervention control group . The first page is cover letter signed by the Secretary of the RUD committee in the region, consisting of general points about the common problems especially in the area which they practice. The second page includes physician’s profile such as name, specialty, medical council number, office address, the evaluation period and the insurance organization that have provided prescription data. Then, the prescription amount of main indicators will be listed in comparative tables that include the following:1. Average medicine items per prescription2. Average price per prescription 3. Proportion of prescriptions including one medicine item (%)4. Proportion of prescriptions including four or more medicine items (%)5. Maximum medicine items in a prescription6. Proportion of injectable medicine items per all prescribed items (%)7. Proportion of prescriptions that includes at least one injectable medicine item (%)Consequently, the prescription indicators for important drug groups such as antibiotics, corticosteroids and NSAIDs will be reported. These groups will be chosen based upon common prescribing problems in any given area. Moreover, the list of 10 most-prescribed drugs and 10 first most expensive drugs are reported in separate tables. Finally, 10 important drug interactions with high severity and intensity in the physician’s prescriptions are reported .The revised audit and feedback has been developed for this trial based on current drug use problems in Iran. We developed our intervention based on four inputs: the current audit and feedback, a literature review, interviews with physicians, and the theoretical justifications acquired from the Theory of Planned Behavior (TPB).We conducted a literature review to obtain feedback’ samples from other countries  and idenThe TPB  is a socThe revised feedback form consisted of three pages. The form uses traffic light colors for reporting the prescribing indicators by physicians. Based on the findings from interviews, the revised feedback form was designed to look less crowded than the routinely conducted feedback and to ensure physicians’ attention was attracted towards important messages in the feedback. The indicators were also selected more objectively. The first page expresses the purpose of providing feedback and interpreting the colors used in the report and the importance of improving the situation of irrational prescribing signed by secretary of the committee. If dexamethasone and ceftriaxone injectable forms and an oral form of cefixime are at the beginning of the list of 10 most prescribed drugs, notice will be given. The revised feedback includes the following indicators on the first page:1. Average medicine items per prescription2. Average price per prescription 3. Proportion of prescriptions including four or more medicine items (%)4. Proportion of prescriptions that includes at least one injectable medicine item (%)5. Proportion of prescriptions that includes at least one antibiotic medicine item (%)6. Proportion of prescriptions that includes at least one corticosteroid medicine item (%)In the second page, table of the most prescribed antibiotics in the country as prescribed by each physician are reported. Then, a graph reports all antibiotics prescribed by a physician and his/her peer group according to differentiate seasons. At the bottom of the second page, two important practice points related to prescribing antibiotics are presented.Table of prescription amount of most prescribed systemic corticosteroids in the country as prescribed by the physician are presented on the third page. Then, a graph reports all injectable forms of medicines prescribed by the physician and compares it with his/her peer group. At the bottom of the third page, two important practice points related to prescription of injectable forms of medicines and corticosteroids are presented.The educational material was also developed using literature review, interviews with physicians, with theoretical attentions based on the TPB. Most physicians participating in the interviews emphasized on the usefulness of a concise pamphlet with a practical training content. Hence, a 4-page A5 size pamphlet was designed. The pamphlet provides practical tips on prescribing antibiotics, corticosteroids and injectable dosage forms and the current status of utilization of these medicines in the country. It also documents examples of serious adverse effects reported from inappropriate usage of ceftriaxone injections and serious complications after dexamethasone injections.The study is conducted in Tehran. All general physicians, pediatricians and infectious disease specialists who have an outpatient practice in Tehran, issue a minimum of 100 prescriptions per month, and have a current contract with at least one of the two main social health insurance organizations are eligible for inclusion in the study.Considering that about 14% of outpatient prescriptions in Tehran contain dexamethasone injections and expecting that the intervention may reduce such prescriptions by 10%, we aimed to recruit 200 participants in each study arm .As the interventions will be delivered to all the physicians allocated to the study arms  and that we used routinely collected data to assess the effects, the prospect of loss to follow was low.To allocate the participants to the study arms, we first prepare a list of all eligible physicians working in Tehran (about 6000 physicians). The physicians will be grouped into the three physician groups . Within each group we will randomly select the required number of physicians, proportional to the size of each group. Using a random number generator, the participants will be allocated to the study arms, and use the physician group and the contracted insurance organization as the stratifying factors. As a result we will have, in each study arm, 175 general physicians, 24 pediatricians, and four infectious disease specialists . Random numbers will be generated by a member of the team who is not involved in the delivery of the interventions.The main outcome measures for assessing the effectiveness of the interventions, the percentage of change in the proportion of dexamethasone injectable form, oral form of cefixime and amoxicillin which prescribed by general physicians, pediatricians and infectious disease specialists will be considered.Costs are assessed from a health care provider perspective. We include all identifiable costs related to the implementation of the interventions. Our analysis therefore focuses on the incremental costs of developing and implementing audit and feedback and printed educational material interventions. Recurring and non-recurring costs are considered. Nonrecurring costs include revising the computer software and designing the new format of the feedback, and the pamphlet. Recurring costs include printing materials, travel costs, postage costs and other administrative tasks.Data at baseline, one month and 3 months after the intervention will be collected.t-test, repeated measure ANOVA and logistic regression analyses will be the primary modes of analyzing the results. As the primary outcomes, we will assess the effects of the study arms on the proportion of prescriptions containing each of the target prescribed medicines. We will also assess the effects of the interventions on the mean cost per prescription, and the mean number of items prescribed per prescription. Appropriate interaction analyses will be conducted to assess the interactions between the selected variables and the interventions. A fixed-effect two-level analysis approach will be followed in which prescriptions will be used as the first level and the physicians as the second level of data.Demographic and baseline analyses will be conducted to ensure random allocation procedure has been effective in producing comparable study arms. Chi-square, Cost data will be assessed using the actual costs incurred in the study, from a health care provider view point. Incremental cost-effectiveness ratios will be calculated and sensitivity analyses will be also conducted to assess the effects of changes in important variables in the cost-effectiveness of the interventions.Intention-to-treat analyses will be carried out with physicians as the primary analysis approach. We will also conduct a per protocol analysis as a sensitivity analysis.These data have been extracted from the Health Insurance Organization claims database and are provided confidentially for each physician for personal review. This study was approved by the Ethics Committee of Pharmaceutical Sciences Research Center of TUMS and has been registered with the Center for International Registration of Clinical Trial.A thorough evaluation of the intervention for improving and promoting rational drug use may bring important benefits, whereas inappropriate prescribing may lead to undesirable consequences. We see this trial as a necessary prerequisite for the development and implementation of a cost-effective intervention that will improve and promote rational drug use in Iran.This study will determine the effectiveness of the three interventions, and allow us to determine what kind of intervention will be the most effective in improving prescribing pattern. This work will be the first to assess the effectiveness and cost-effectiveness of the routinely conducted audit and feedback that has been widely used in the country.The risk of contamination between the study arms is a potential limitation of the study. However as the study sample is selected from a large number of physicians working in Tehran, the risk of contamination should be small. Additional potential limitation of the study may arise due to concurrent interventions that might happen by the responsible authorities within the Ministry of Health and Medical Education, as well as the universities in charge of health care in Tehran. We will follow such activities throughout the study, and will assess their potential impacts on the study findings, if they occur.We believe that the current proposal may have other benefits. We expect that it will lead to the development of focused interventions that could greatly promote rational drug use. Changing physician’s behavior is challenging and involves attention to the views and concerns of practicing physicians. We attended to the physicians’ views while developing our interventions. In addition, this trial shall establish whether the design of targeted feedback can be used as a novel format of interventions for promoting rational drug use. We hope that, if our interventions are cost-effective, they shall be widely applied nationwide. The interventions may also be of use in middle income countries with appropriate infrastructures.Authors have no conflict of interest. Since MA is Editor-in-Chief of DARU, all the review process is handled by one of Section Editors.AR, FS designed the study with contributions from RD, AK, MH, and MA. FS collected data, registered the study and wrote the first draft of the manuscript. FS and AR revised the manuscript based on comments from the other authors. All the authors approved the final manuscript.


Motion simulators are widely employed in basic and applied research to study the neural mechanisms of perception and action during inertial stimulation. In these studies, uncontrolled simulator-introduced noise inevitably leads to a disparity between the reproduced motion and the trajectories meticulously designed by the experimenter, possibly resulting in undesired motion cues to the investigated system. Understanding actual simulator responses to different motion commands is therefore a crucial yet often underestimated step towards the interpretation of experimental results. In this work, we developed analysis methods based on signal processing techniques to quantify the noise in the actual motion, and its deterministic and stochastic components. Our methods allow comparisons between commanded and actual motion as well as between different actual motion profiles. A specific practical example from one of our studies is used to illustrate the methodologies and their relevance, but this does not detract from its general applicability. Analyses of the simulator’s inertial recordings show direction-dependent noise and nonlinearity related to the command amplitude. The Signal-to-Noise Ratio is one order of magnitude higher for the larger motion amplitudes we tested, compared to the smaller motion amplitudes. Simulator-introduced noise is found to be primarily of deterministic nature, particularly for the stronger motion intensities. The effect of simulator noise on quantification of animal/human motion sensitivity is discussed. We conclude that accurate recording and characterization of executed simulator motion are a crucial prerequisite for the investigation of uncertainty in self-motion perception. For more than a century, motion simulators have been employed in neurophysiological, psychophysical and behavioural studies that aim to inform the neural and cognitive processes of self-motion perception While there has been significant prior research on designing, diagnosing and comparing motion systems 2. Participants were asked to discriminate a reference motion, repeated unchanged for every trial, from a comparison motion, iteratively adjusted in amplitude to measure the participants’ motion discrimination thresholds. Different reference motions were tested in different experimental conditions. When interpreting the experimental results, the undesired noise introduced by the simulator is of concern for two main reasons:To facilitate the description of the methodologies and their relevance, we will use a psychophysical study conducted by the authors 1. The total noise level of reference and comparison motions within each condition, if noticeably different, would provide additional cues to the participants.2. The increase of the total noise level with motion intensity, if non-linear, would lead to a non-constant Signal-to-Noise Ratio (SNR), resulting in differences in stimulus quality across the tested motion range.Note that, although different experimental procedures have been proposed and used in the literature to investigate the perception of self-motion, none are immune to these problems.The first point has been raised already by A different approach, employed by To the best of our knowledge, the second point, concerning changes in the signal quality across the tested motion intensity range, has never been addressed in any psychophysical study on self-motion perception. Substantial evidence indicates that the SNR of motion simulators depends on the commanded motion intensity and frequency cf.  and thatFor our chosen example study 2  with a 3D accelerometer  attached rigidly on the back of the simulator seat. While our trajectories did not involve rotations, it is important to note that for rotational trajectories, seat and head motions differ and placing the IMU on the participant’s head is a more sensible choice. For each reference stimulus, we additionally recorded two comparison stimuli whose peak intensity was raised (higher comparison) and lowered (lower comparison) by two corresponding discrimination thresholds, so as to quantify the noise level changes within stimuli of the same condition. The discrimination thresholds associated with the reference stimuli are 0.02 (unpublished observation), 0.09, 0.21, 0.23 and 0.25 m/s2, respectively 2. The deterministic component was obtained by averaging the total noise across repetitions of each profile, and the stochastic component was obtained by subtracting the deterministic component from the total noise.The study was conducted using the Max Planck Institute CyberMotion Simulator, a 6-degrees-of-freedom anthropomorphic robot-arm, able to provide a large variety of motion stimuli, with a maximal vertical displacement of about 1.4 m and a maximal vertical linear acceleration of about 5 m/sTwo different methods were employed to analyse the total noise level of the profiles: the amplitude-frequency spectrum and the root mean square (rms). These methods are explained in more details in the following sections. Additionally, for the 10 reference stimuli, the SNR was computed to characterize the relationship between the quality of the reproduced motion and the intensity of the commanded motion . We further analyse these stimuli in terms of the deterministic and stochastic components of their total noise . Signal processing and statistical analysis were performed in MATLAB (2012a) using custom-written code and the Statistics toolbox.i hat is the i-th sample of the windowed signal, xi is the i-th sampled measure of noise and N is the number of samples (in this case 1500 samples).The total noise affecting the motion profiles can be objectively quantified by its amplitude-frequency spectrum. Such an indicator has the advantage of providing details about which frequencies are more affected by the noise. This approach, based on After Fourier transforming the windowed signals we obtained 3 groups of 20 amplitude-frequency spectra for each condition : one groanalysis of vibration reported in The same analysis was also performed on the stochastic noise so as to allow for comparison with the ix is the i-th sampled measure of noise and N is the number of samples (in this case 500 samples). For each condition we obtained 3 groups of 20 rms values each: one group for the reference motion, one for the higher comparison and one for the lower comparison, which were all repeated 20 times. To determine whether noise level changes within conditions are reliable cues for motion amplitude discrimination, every reference rms group was tested for statistically significant differences (unpaired 2-sample t-test) against its corresponding higher and lower comparison independently. This rms analysis was conducted on the total noise as well as the stochastic component of the noise. Results of these analyses are shown in The rms, or quadratic mean, is a measure of the magnitude of a varying quantity. Here, its discrete formula is used to objectively quantify the noise level of each 1 sec signal:2 for the simulator tested here) The SNR is used to express the relative amount of commanded signal and background noise present in each trajectory. A SNR close to 1 indicates that the level of noise in the reproduced motion is comparable to the level of commanded signal. This is often the case for motion simulators when reproducing small accelerations (e.g. <10 cm/s2). See Differences in the SNRs were tested with an ANOVA with 2 factors: direction (upward or downward) and motion intensity . We calculated the rms of the stochastic and deterministic noise for the 10 reference motions. The Deterministic-to-Stochastic Ratio (DSR) introduced in Even when recording no motion, a certain level of background activity is to be expected in any IMU recording. This is due to electrical interferences as well as specific traits of the IMU, which obviously do not reflect real motion. New software and hardware improvements are continuously being developed to reduce this sensor noise see e.g. , howeverThe tested reference/comparison pairs show significantly different total noise levels both in terms of amplitude-frequency spectrum and rms of the total noise signals in almost every tested pair . This in2) and the motion profiles  correlates with the inverse of the square root of the number of trials averaged . However, sensor noise analysis revealed comparable noise levels between the no-motion profile  = 25037, p<0.001) over the tested range, which leads to SNRs that depend on the motion intensity . The resThe rms of the stochastic and deterministic noise of each reference profile for upward and downward movements is presented in The analyses presented here allow characterization of the noise introduced by the simulator when reproducing commanded trajectories. They provide sensitive methods to compare the noise level of different commanded stimuli and to graphically and statistically describe the reproduced motion. Results show that the total noise of the simulator increases with the amplitude of the command in a nonlinear way, leading to an SNR that increases with the motion intensity. Even for relatively small changes in the amplitude of the commanded motion, changes in the measured noise are statistically significant. This raises the question of whether a human, when asked to report changes in the motion intensity, could use changes in the simulator noise as a cue rather than changes in the signal itself.It is reasonable to assume that, if our analyses of the IMU signals do not demonstrate these differences, the human will also not detect them. It is however erroneous to conclude the opposite. The simulator motion is available to the CNS only after being processed by the sensory systems , whose dynamics are imperfect due to frequency dependences and noise Given these results and the previous considerations, speculations can be made as to how simulator noise affects human perception of motion intensity. To distinguish between motions at different intensities, differences in the neuronal signals that reach the CNS need to overcome the internal noise level By including a demonstration of the proposed methodologies in this paper, we raise the practical concern of sensor noise, which affects any measuring setup regardless of the sensor nature . Sensor measures during no motion allowed us to estimate the level of sensor noise and to conclude that stochastic components of the noise motion are likely smaller than the level of sensor noise, indicating that simulator-introduced noise is primarily of deterministic nature. A more precise quantification of the stochastic motion noise was precluded by the stochastic sensor noise. Overall, caution is advised in the interpretation of sensor measurements as much as in the interpretation of responses to noisy self-motion stimuli.To address the stochastic and deterministic composition of the total noise, we have provided their formal definitions and a methodology for extracting them from IMU recordings. Other than using the DSR introduced here, deterministic and stochastic noise can also be compared using a frequency analysis, which is particularly useful for highlighting the frequency ranges affected by the two types of noise (see the examples in Whenever possible effort should be spent in minimizing the deterministic noise, so that its impact during experiments is also minimized. This is particularly beneficial in cases where a DSR analysis indicates a predominantly deterministic nature of the noise. Deterministic noise can be reduced by using iterative learning control algorithms Simulator-introduced noise is a recurrent concern for neuroscientists who use motion simulators to investigate the neural and cognitive mechanisms of self-motion perception. In this work we developed straightforward graphical and statistical techniques for the analysis of motion stimuli commonly employed in self-motion studies. Rather than measuring the dynamic qualities of a motion system, these analyses allow for dissociation between simulator and physiological noise and therefore constitute a valuable set of tools for the interpretation of neurophysiological and behavioural responses, as well as for meaningful comparisons across the existing literature. We further illustrated these analyses and their relevance using a prior study on human self-motion perception. Results clearly demonstrate the importance of noise, including both stochastic and deterministic components. It should be noted that, although the methods are of general application, the presented results hold for the employed simulator only and other simulators are expected to show substantial differences in their dynamic responses.