Acipenser oxyrinchus desotoi) and Green Sturgeon (A. medirostris), we illustrate what is known about well-studied species and then explore lesser-studied species. A more complete picture of migration is available for North American sturgeon species, while European and Asian species, which are among the most endangered sturgeons, are less understood. We put forth recommendations that encourage the support of stewardship initiatives to build awareness and provide key information for population assessment and monitoring.Worldwide, sturgeons (Acipenseridae) are among the most endangered fishes due to habitat degradation, overfishing, and inherent life history characteristics . As most sturgeons are anadromous, a considerable portion of their life history occurs in estuarine and marine environments where they may encounter unique threats . Of the 16 marine-oriented species, 12 are designated as Critically Endangered by the IUCN, and these include species commercially harvested. We review important research tools and techniques  and discuss the comparative utility of these techniques to investigate movements, migrations, and life-history characteristics of sturgeons. Examples are provided regarding what the applications have revealed regarding movement and migration and how this information can be used for conservation and management. Through studies that include Gulf ( There are 27 species of sturgeons and paddlefishes (Order Acipenseriformes) in rivers, lakes, estuaries, near-shore oceanic environments, and inland seas across the northern hemisphere . The twoSturgeons are generally long-lived fishes that exhibit late onset of maturity, slow growth, and infrequent reproduction Sturgeons are also some of the least-well-known of the major taxa of concern in terms of spatial distribution and abundance, particularly for oceanic and nearshore phases of their life history. Almost all of the sturgeons that enter into saltwater have been understudied with respect to where they go and why  and manySturgeons may move from one location or habitat type to another to feed, reproduce, or overwinter. River movement can be complex and include multi-step migrations Preserving the evolutionary potential of a species and its ability to respond to environmental change requires understanding the number of distinct populations within a species. Natal homing fidelity is thought to be strong and thus in many cases rivers, or sections of a watershed between natural barriers, often define populations. On the other hand, metapopulations may also exist Knowledge about movement and the spatial distribution of populations can also improve population assessments and help in specifying suitable management or recovery plans. Population assessments are still lacking for most species and are often hindered by an insufficient understanding of spatial distribution. Sturgeon species and/or populations with an anadromous life-history strategy may require assessment models that account for the seasonal movement patterns of different life-history stages exploited by fisheries Insufficient data for parameterisation of models for migratory species with complex life histories can lead to large uncertainties in resource assessment and the likely effects of alternative management actions. The lack of data for key parameters of population dynamics has been identified as a contributor to the depleted and endangered status of many sturgeon populations throughout their range Acipenser oxyrinchus desotoi, a subspecies of the Atlantic Sturgeon, Acipenser oxyrinchus, occurs in most Gulf of Mexico river systems from the mouth of the Mississippi River to the west coast of Florida . This resulted in designation of nearly 2,800 river km as critical habitat for conservation of the species.In contrast to the relatively well-studied Gulf Sturgeon, the North American Green Sturgeon was little studied until 2002, when the US National Marine Fisheries Service received a petition to list it under the US Endangered Species Act. A severe lack of demographic and basic life-history information hampered the subsequent status review The recent development of new telemetric tagging systems made it feasible to rapidly close some of these information gaps. Initial work focused on Green Sturgeon in the Rogue River, using radio and acoustic tags to learn that Green Sturgeon migrate into rivers in the early spring for spawning in up-river areas, and then hold in deep pools over the summer prior to emigration in the fall when flows rise with the onset of the rainy season A broader study using acoustic tags showed that Green Sturgeon make extensive seasonal migrations among spawning areas, over-summering in various estuaries and bays, and over-wintering areas in the coastal ocean, with many individuals using areas around northern Vancouver Island In summary, the application of electronic tag technology to study Green Sturgeon revealed novel, reliable, and useful/relevant information regarding marine migrations and habitat use, spawning locations and periodicity, and both marine and freshwater life history attributes. While tagging revealed clear overall migration patterns, it also revealed a diversity of migratory behaviours that are likely important to consider in the conservation and protection of this species. Complementary genetic studies have determined that two distinct population segments exist within Green Sturgeon that correspond to northern and southern populations, and that estuarine aggregations contain individuals from multiple populations The Caspian Sea is one of the most important areas for sturgeons globally and has supplied much of the world's wild caviar. Five of the species that inhabit this region , fingerlings may overwinter in river deltas while for others (e.g. Beluga), fingerlings will migrate into the Caspian Sea for rearing. Information regarding the behaviour and movement of juveniles as well as adults within rivers has been gathered through fisheries-dependant surveys and fisheries-independent studies using nets. While a few tagging studies have been attempted e.g. , none haIt is unclear whether adult sturgeon in the Caspian Sea return to their natal rivers for reproduction. Genetic studies using mitochondrial DNA have not shown differentiation amongst river populations Within the Caspian Sea environment, comprehensive information about the distribution of sturgeons is lacking (A. sturio) and Adriatic Sturgeon ; the presence of exotic species and hybrids is particularly problematic in this region. The area is represented by small, sometimes relict populations such as the European  Sturgeon A. oxyrinchus oxrinchus) to the Baltic Sea and European Sturgeon to the Elbe River in Germany, providing key information on food selectivity, migration patterns, and potential sources of mortality. This study was important to the success of reintroduction efforts  and in guiding planned restoration and habitat protection efforts. Tagging will eventually reveal whether reintroduced animals survive to adulthood and return to their rivers of release to reproduce. This study as well as Restoration projects for European and Atlantic Sturgeon have released marked  juveniles from captive breeding facilities to track subsequent movements and habitat use The Black Sea is home to the same commercially important species of sturgeon as found in the Caspian Sea, with the Danube River supporting the largest populations. Sturgeons in this region have also been impacted by fishing and habitat degradation and the focus of scientific research is often on restoration, recovery, and management. In the Black Sea, acoustic tagging studies have been used to examine spawning location and timing for Stellate (A. stellatus) and Russian Sturgeon (A. gueldenstaedtii) in the lower Danube River A. schrenckii) and Kaluga (Huso dauricus) Sturgeon of the Amur River are commercially exploited for meat and caviar. These species are thought to have complex population structures, undertaking considerable migrations within the river (Amur Sturgeon), and marine environment . The Sakhalin Sturgeon inhabits the Russian Far East and is believed to have a primarily marine life history; it is one of the least studied of the sturgeons and is also one of the most critically endangered, with spawning populations possibly reduced to a single river. The Chinese Sturgeon, A. sinensis, has benefited from studies aimed at understanding movements in relation to dams and habitat protection The Russian Far East and China include little-known (and under-studied) anadromous sturgeon species The application of individually numbered or coded tags to fish prior to release is typically referred to as “tagging.” The term “marking,” while sometimes used as a substitute for tagging, is typically used to reference batch or group “mark” applications. Subsequent recaptures of tagged fish can yield information on movement, time at large, growth, etc., whereas recaptures of marked fish will provide general information only regarding the entire “mark group.” If recapture and reporting rates are sufficiently high, capture-recapture data from tagging studies are very useful for population assessment, providing information on population size, size/age structure, movement rates, fishing/natural mortality, and fish behaviour.Sturgeon are long-lived animals; thus, tags or marks that can be positively identified many years following release are ideal. Although not always feasible, determination of sex and maturational stage of individual sturgeon used in long-term tagging studies can provide greater insights regarding interpretation of subsequent movement and migration patterns. If tagging involves tag implants in the body cavity , the process should include visual determination of sex and stage or analysis of plasma concentrations to identify sex The use of uniquely identifiable tags can provide comparative growth and condition information for long-term studies with adequate sample sizes Marking sturgeon with traditional methods such as dye marking, tattoos, pigment implantation, or freeze branding is not recommended for studies that intend to report recaptured marks over a long time span , as these marks cannot be clearly identified on sturgeon within several months or a year of application. Another more-permanent marking approach to be considered, with caution, is scute removal Other permanent marks that have been applied to sturgeon include barbel clipping and fin ray removal. Barbel removal is not recommended due to the importance of barbels to sturgeon sensory physiology and the reduction in fitness and increase in mortality it can cause Tag types for sturgeon fall into three major categories: external tags, internal tags, and electronic (telemetry) tags. For the purposes of this paper, internal tags will be limited to Passive Integrated Transponder (PIT) tags, which are small, individually coded tags that are injected  into the body musculature or internal body cavity of sturgeon and are detected with a hand-held electronic tag reader. The use of electronic tags  and utility of associated telemetric tag types  is presented in section 2.1.4 of this paper.External tags – External, non-telemetry tags are typically attached to dorsal or lateral locations on the sturgeon with the intention to minimize the impact or influence of the tag  and maximize tag retention. Some external tags are applied with an application tool , while others may be attached by hand, sometimes with the use of an applicator or needle. Tag materials include plastic, PVC, nylon, and metal, and may be available in various colors to attract attention and/or assist with individual or batch identification. External tags are typically labelled with information that includes a unique tag number, and may include contact information for tag reporting, such as an address or phone number. Retention rates for external tags applied to sturgeon vary; some can maintain retentions above 70% for up to 3 years while other external tag application/types may not provide the high levels of tag retention rates required for mark-recapture analyses Common external tags used for sturgeon include: the “monel” tag ; the “disc” tag ; and the “anchor” or “T” tag, which is typically a 3–5 cm length of small-diameter PVC tube with a “T” shaped plastic anchor at one end. The “cinch” tag  is similar to a long anchor tag except that the ends are attached (forming a loop). Popular attachment points for external tags are typically near the dorsal fin  or the edge of the operculum or pectoral fin .Internal (PIT) tags – A popular and effective tag for sturgeon is the PIT tag, a small, uniquely coded electronic tag that is applied internally via a hand-held applicator (syringe). Long-term retention rates for PIT tags are typically above 95% PIT tags can also be detected with PIT tag antennas that are built into passive underwater apparatus such as tubes, loops, or mats; when a PIT tagged sturgeon passes through or near the antenna, the tag code is logged with time and date in the memory of a receiving unit (connected by cable to the antenna apparatus or array) that is later downloaded. This application may be effective to gather recapture data for constricted locations where tagged sturgeon are forced to pass through a confined area. For some applications, remote PIT tag detection may provide information to calculate overall survival Considerations for PIT tags – PIT tags are typically more expensive (in the order of 5–10 times more expensive) per tag than most external tag types but have high retention rates. PIT tag information is transmitted from the tag by way of a specific radio frequency; both the tag and tag reader must be compatible and using the same frequency. Thus, when committing to a long-term research project that uses PIT tags, it is important to determine the long-term availability of both the tags and the compatible tag readers. Also, researchers should determine if other sturgeon researchers that have worked or are working on the target population or species have applied PIT tags to sturgeon. If so, new studies that include PIT tag applications may want to consider using the same tag frequency so that previously tagged sturgeon can be identified.The rapid advancement of electronic tag technology (telemetry) has facilitated an explosion of research on sturgeon life history, which in turn has generated novel insights into migratory behaviour, habitat use, and demographic processes. Electronic tagging offers advantages over traditional tagging approaches requiring large sample sizes to overcome low recapture rates. Electronic tags can be categorized by several characteristics. One distinction is whether tags transmit data in real-time to receivers (telemetry tags) or store data to internal memory for transmission at some later date . Telemetry tags can be further differentiated by signal transmission mode: acoustic or radio. To date, telemetry tags have been most widely used in sturgeon research, although archival tags have been used with great success in studies of oceanic fish and marine birds.Acoustic tags transmit identification codes  to hydrophones over a limited range . Radio tags are similar, with differences related to signal transmission mode: radio waves propagate well through air and freshwater, but poorly in hard or saline water. Because acoustic or radio tagged fish need not be recaptured and can be detected at a distance, strategically placed receivers can collect large amounts of data on tagged fish. Combined acoustic and radio tags (CART) combine both transmission modes, allowing radio receivers to be used in freshwater and acoustic receivers to be used in brackish and saltwater. For both kinds of tags, information about the tagged fish is only collected from fish within the detection area of receivers. This shortcoming can be overcome by archival tags, which record signals from various sensors and store them internally. Typical information recorded by archival tags include pressure (depth), temperature, and light level, which allows estimation of location based on sea surface temperature and the time of sunrise and sunset Use and utility of telemetry tags – We searched the primary literature for sturgeon studies reporting the use of electronic tags, and found 55 relevant studies . These studies have used all types of telemetry tags and tracking methods, and most have used acoustic tags, or a combination of acoustic and other tag types. The study of n = 5) have relied on acoustic tags and mobile tracking, with the exception of a study of Green Sturgeon in Willapa Bay (Washington) and the Columbia River estuary Movement and habitat-use studies in estuaries ; however, in order to achieve reliable outputs, several challenges must be solved. These include achieving large-enough sample sizes to reliably estimate the many parameters of such models, and dealing with the problem that detections of tagged sturgeon occur over the same time interval as the mortality process. Typical capture-recapture models assume that there is no mortality during the recapture process, which in some cases can be instantaneous.The data gathered from tagging studies that use simple  tags and/or telemetry can potentially provide information on a number of life-history characteristics that are necessary to model population dynamics . Using life-history traits to understand how populations may respond to perturbations such as harvest has been advocated as a useful approach to predicting extinction vulnerability and formulating management strategies Applying genetic techniques allows a researcher to understand the species that are present in a given area  and the movements of sturgeons on multiple spatial scales and through evolutionary time [see references in this section below]. An important question that can be addressed using genetics is that of where an individual animal reproduces. As a first step in answering this question, reproductively isolated populations of a sturgeon species must be identified through genetic analysis. By knowing the number of isolated populations, appropriate conservation schemes can be created that preserve the evolutionary and ecological potential of a species. The protection of multiple populations can serve to buffer against extinction due to environmental change. Many sturgeons are thought to return to their natal river to reproduce and it is this behaviour that creates genetic structure and separate populations. It is unlikely, on the timescale of interest to managers, that animals from one river system would replace those in another if an individual population were to go extinct; thus, it is important to minimize individual population extinction since translocation of individuals from other populations should only be used as a last resort. A related point is that of identifying the presence of non-native species or hybrids in an area as an important step in conservation planning.While information on the location of reproduction can be obtained through tagging studies, this approach does not answer the question of whether the animal effectively breeds in an area. Evidence of spawning can be gathered through biochemical means , the deployment and monitoring of egg-mats or larval traps, or specifically designed electronic tagging studies, but only genetics can pinpoint whether the individual contributes to the next generation. In addition, it may be easier and less costly to use genetics to track breeding. As described below, once the overall genetic structure of a species is characterized, it can be fairly straightforward to identify the population origin of any individual at any location. Combining tagging and genetics can further provide a more comprehensive picture of population structure as defined by present and historic habitat characteristics Some of the fundamental questions that can be addressed using genetics include:Which species or species hybrids exist and reproduce in a given area ?How many populations exist within a species? Where do individuals from these populations breed and feed?Does a specific area in the ocean or in an estuary include individuals from a single population or multiple populations and, if the latter, which ones?Do two or more populations exchange individuals?Ideally, a genetics study will begin with comprehensive sampling of all potential spawning populations. For some sturgeons , multiple spawning populations may exist within a single river system. Population differentiation can result from differences in timing or geographic location of spawning and can occur in the absence of any physical barriers separating populations. The samples taken from each population should ideally have corresponding information about the relative age of the animals  and the spawning stage of an adult. Information on life stage of the sample becomes especially important when sampling is conducted in lower reaches of the river and in estuaries because individuals can congregate in estuaries and coastal environments that are not in close proximity to their natal river of origin. When species or hybrid identification is a concern, sampling multiple life-stages can yield insight on whether non-native species or hybrids are effectively breeding in an area.Sequencing of mitochondrial DNA (mtDNA) is one of the easiest genetic techniques to use for identifying the species present in an area (including non-natives) and studying movement, distribution and population structure and has been extensively applied e.g. With respect to delineating population structure, one of the best examples of the utility of mtDNA comes from the east coast of North America. The Atlantic Sturgeon has been particularly well studied and this work has shown fine-scale population structure and spawning site fidelity Unlike mtDNA, microsatellites are biparentally inherited and genetic studies using these markers would not be biased by sex-specific differences in movements. In addition, microsatellites are highly polymorphic and may reveal population structure on a finer scale than mtDNA. There is less ease in applying this technique across species and species-specific marker development is sometimes necessary. Complications can arise in using microsatellites for polyploid sturgeons , as some species may possess eight or twelve chromosome copies, however, the use of microsatellites to study populations can be achieved if Mendelian patterns of inheritance of microsatellites are found Microsatellites have been particularly useful in characterizing the marine distribution of Green Sturgeon and these studies, along with those on non-marine oriented sturgeons  Many studies use both mtDNA and microsatellite markers. One interesting application, which also used four single-nucleotide polymorphisms (SNPs), is the study of the historical distribution of European and Atlantic Sturgeon. Study of archived and historic specimens revealed that Atlantic Sturgeon colonized an area in the Baltic Sea that was formerly thought to only be inhabited by European Sturgeon Emerging approaches include single-copy nuclear genes and SNPs There are many different analytical tools in the field of population genetics that can be applied. Measures of genetic differentiation such as genetic distance, F-statistics, analysis of molecular variance (AMOVA), and exact tests can be employed to identify distinct sturgeon populations and measure gene flow between them. These methods are most useful when samples can be obtained from spawning adults or newly hatched larvae in a natal river, where a researcher can be assured that the individuals sampled belong to a particular spawning population. When sampling is conducted in a region of potential mixing between populations , the origin of each individual examined is unknown and other methods are necessary to examine population structure. Population assignment testing can be used with microsatellite or SNP markers to identify the population of origin of individual sturgeon in an area of potential mixing. There are several types of population assignment tests but they all exploit differences in allele frequencies between populations to assign individuals to their natal population. The software program STRUCTURE Differences in trace elemental profiles between habitats or bodies of water can be exploited to learn more about the migratory behaviour of fishes. Gradients in elements such as Sr, Ba, Ca, Mg, S, and B exist in regions of different salinities, temperatures, and bedrock influences Otoliths are used most often in microchemical analyses of fishes since, unlike scales or skeletal bones, there is no potential for resorption or remodelling of this structure One advantage of otoliths and fin rays is that changes in elemental composition between regions of incremental growth may be used to reconstruct patterns of movement in these fishes over time Applications of microchemical techniques to understanding sturgeon movements have been limited to this point, focused primarily on examining changes in marine and freshwater habitat use over the lifetime of an individual. In a study that confirmed the utility of fin rays for examining sturgeon movements ex situ experiments to evaluate whether elemental deposition of Sr, Ba, and Ca in Green Sturgeon fin rays was proportional to environmental concentrations of these elements in freshwater and seawater environments. It was confirmed that ambient ratios of elements in freshwater and saltwater were nearly identical (Sr:Ca) or proportional  to the ratios found in fin rays of individuals held in freshwater or saltwater, respectively Approximately 10% of lower Fraser River White Sturgeon subadults between ages 1–15 showed Sr:Ca ratios that were consistent with migration into the marine environment, although these movements did not appear to be seasonal or periodic Microchemistry techniques might be applied to resolve many questions regarding sturgeon movements and habitat use. Although there are some uncertainties associated with deriving age estimates from sturgeon fin rays Microchemical techniques have the potential to provide a great deal of information about sturgeon movement and life history. However, interpretation of elemental profiles in fish bony structures is dependent on an accurate understanding of the factors that influence element deposition. Additional work to ascertain the influence of water temperature, salinity, and the interaction between these parameters on element deposition in sturgeon otoliths and fin rays must be conducted to avoid misinterpretation of elemental profiles Sturgeon can occupy marine environments or large, deep and typically turbid river systems where direct visual observation of behaviour, movement, or habitat use is difficult and often impossible. Consequently, until recently, what little was known about these attributes of sturgeon ecology were based on anecdotal observations or inferences drawn from capture and tagging studies. In the last two decades, substantial advances in remote sensing technologies have provided researchers with a greater variety of tools that allow direct observation of sturgeon behaviour and habitat use. These technologies can generally be grouped into two categories: those that use underwater cameras to provide light-based images and those that rely on sound waves to produce sonic-based images. Each of these observational categories and their applicability for use in studying sturgeon behaviour and habitat use is discussed below. Although most of the applications encountered in the reviewed literature were used for the study of sturgeon in freshwater systems, in many instances they also have applicability for the study of sturgeon and their habitats in marine and estuarine environments.The use of underwater photography as a tool to examine sturgeon behaviour has only recently begun to be explored. Advantages of using underwater cameras are the ability to directly observe fish in their natural habitats and for some sturgeon species, the absence of any apparent avoidance behaviour of underwater cameras and lights. Disadvantages include limited use in aquatic environments with low water clarity and difficulties in long-term monitoring of fish that are engaged in active feeding or large-scale movements.http://videos.oregonlive.com/oregonian/2008/05/sturgeon_ball.html). An ROV also was used to identify critical overwintering habitats for the endangered White Sturgeon in the Nechako River, a tributary to the Fraser River in British Columbia, Canada Obtaining underwater footage has been facilitated in recent years through the development of small submersible Remote Operated Vehicles (ROVs) and technological advances in low-light digital and video cameras. ROVs have been used in freshwater applications to examine the real-time effects of hydroelectric plant operations on sturgeon feeding behavior Underwater video camera systems have been used to study overwintering habitats of Shortnose Sturgeon in the upper Kennebecasis River, New Brunswick, Canada Over the last three decades, active hydroacoustic techniques have developed and proven to be a relatively easily applied method of unobtrusively evaluating fish populations in freshwater and marine environments http://www.hydro-international.com/issues/articles/id920- Synthetic_Aperture_Sonar_Challenges.html). This technology has become commercially viable and the technique is well suited for towed or remotely operated underwater vehicles. SAS is expected to replace traditional side-scan sonars for many applications in the future.Mobile survey hydroacoustic techniques are generally conducted from a boat, traversing predetermined transects in a body of water, and sampling fish and bottom characteristics All acoustic systems have some sampling limitations with respect to their ability to resolve targets very close to boundaries, such as the bottom. Sturgeon are primarily benthic oriented and often in close proximity to the bottom. In addition, research describing sturgeon target strength, or the amount of acoustic energy reflected from the fish, is limited. To be effectively detected, a fish must return target strength values greater than the surrounding background noise levels. The primary reflecting structure in most fish is the swim bladder, although bones, scutes and other body structures do provide some contribution Split Beam – The main advantages of split-beam over other hydroacoustic techniques are improvements in location within the acoustic beam and in minimized susceptibility to noise Split-beam hydroacoustics was used to detect Shortnose Sturgeon in the Delaware River Fixed-location split-beam sonar technology was used successfully to identify adult Lake Sturgeon as they moved upstream and downstream for spawning in the Sturgeon River, Michigan Side Scan – Trawling and side scan sonar analysis was used to document an area of consistently high Lake Sturgeon density in Lake St. Clair near the St. Clair River delta On the lower Missouri River, side-scan sonar data were collected in areas that contained suitable habitats for both Shovelnose Sturgeon and Pallid Sturgeon http://www.thsoa.org/hy09/0512P_02.pdf). Areas of high-frequency sturgeon occurrence (as determined through concurrent telemetry studies) were targeted using a side-scan sonar system. Numerous habitat features were identified and the data will be integrated with tracking data and habitat imagery to identify essential Atlantic Sturgeon habitats.Researchers in Virginia used side-scan sonar to characterize the benthic habitats of Atlantic Sturgeon in the James River and identify habitat attributes that may be required to sustain viable sturgeon populations . Units that allow setting the window size for a specific number of feet while in bottom track will provide higher signal resolution that will show any irregularities on the bottom as well as fish holding right on the bottom. Sturgeon that are suspended some distance above the bottom show up quite well on most high-resolution fish finders (http://www.nwfish.com/images/graphics/ffshotsturg1.jpg). Sturgeon holding tight to a hard bottom are difficult to identify and are usually represented by a “spike” or “bump.” (http://www.nwfish.com/images/graphics/ffshotsturg2%20.jpg).TMDIDSON – In large rivers, a common approach for estimating population size of anadromous fish is to count upstream-migrating fish at a fixed site, using split-beam hydroacoustic equipment. A disadvantage of split-beam sonar in this application is that it generally does not provide sufficient information to allow species identification. A newer technology that can be used to count upstream migrants is the DIDSONTM , a high-definition imaging sonar that provides near-video-quality images. When used at a range of 5–10 m, video files clearly show body shape and swimming behaviour of individual fish. Split-beam gear provides more precise information about fish position, but DIDSONTM data are much easier to interpret, can be used to identify sturgeon to genus, and allow for on-screen measuring of fish lengths. Initial field trials showed potential for utilizing these technologies to determine habitat, identify sturgeon, and estimate densities . DIDSONTM has also been used to document White Sturgeon presence and activity in the vicinity of power plant outlets TM imagery, combined with intensive telemetric tracking. This approach provided measures of habitat availability and selection variables at sub-meter to bedform scales, commensurate with the scale at which fish occupied these habitats. The DIDSONTM imagery indicated that during spawning, sturgeon occupy the lee slopes of dunes facing upstream (presumably to minimize energy expenditure) but episodically move out of dune fields and into deep, fast water over coarse substrate (presumably to release eggs and milt). This multi-scale, multi-instrument remote-sensing approach was essential for improving understanding of the linkages between life stages of a rare fish and its environment.Restoration and management of the lower Missouri River to support recovery of the endangered Pallid Sturgeon required quantifying habitats to isolate specific habitats that may present bottlenecks to reproduction and survival At present, observational techniques for sturgeon research have primarily been used to provide information on sturgeon behaviour and habitat use. These techniques enable researchers to directly observe sturgeon in their natural environment in a manner that does not influence their behaviour and have substantially increased our knowledge of how sturgeons interact with each other and their environment. Most importantly, these techniques have identified critical sturgeon habitats that in turn have resulted in the protection of those habitats through direct management regulations. As these observational techniques are developed further, their potential uses will continue to expand. Direct observation of sturgeon behaviour at dams and existing fish passage facilities, either through video or sonic imagery, can be used to provide information that may lead to the development of appropriate passage facilities for anadromous sturgeon. As sonar techniques are refined and new algorithms to process and interpret digital signals are developed, these techniques have the potential to be used to identify individuals and provide assessments of sturgeon distribution and abundance over large areas.The marine life history and distribution of many sturgeons remains a mystery. However, new technologies developed over the past two decades have greatly increased our knowledge base. Refined methods of analyzing DNA provide fine-scale information about genetic structure at the river basin or even sub-basin level. Improvements in telemetry equipment and observational techniques have allowed researchers to identify and characterize key habitats, from spawning sites at the upstream extent of migration to overwintering sites and migratory paths in coastal ocean waters. Telemetry and tagging studies have also shown that estuarine and marine sites used for foraging or overwintering may contain sturgeon from multiple populations. Tagging, genetic, and observational studies have revealed that sturgeon can travel considerable distances from their natal rivers, but that they generally inhabit coastal, shelf areas during their migrations. Also, individuals generally seem to return to natal rivers for reproduction. Taken as a whole, this information shows that sturgeons have complex life-history strategies that are reliant on specific habitats for different life stages. As such, fully protecting a given species requires a comprehensive approach that includes research and conservation efforts in riverine and marine environments.Yet even with these technological advancements, there are few sturgeon species for which we have a fairly comprehensive understanding of respective life histories, particularly in the marine environment. For the 16 marine-oriented sturgeons, only two (Green and Gulf Sturgeon) have been well studied with respect to their marine distribution  have been successful Data collected by the methods described here can provide useful insights into the life history of sturgeon populations, and enable management and conservation. For example, information regarding temporal and spatial movements, migrations, and periodic residency, coupled with a general knowledge of life history events such as spawning and in-river overwintering, could provide a high level of confidence regarding the location and extent of proposed habitat protection for population conservation and recovery. Genetic data on population structure is essential for identifying particularly vulnerable or endangered populations and setting appropriate management actions to conserve them. Gaining an understanding of life-stage-specific movement patterns and spatial distribution is also required to properly assess the impacts of anthropogenic activities such as fishing, dredging, and gravel extraction and to specify management actions accordingly.All of the techniques discussed require a certain amount of specialized training. Protocols for proper handling, short-term holding, tag applications, and tissue sampling have been produced for some species


In vitro recordings of medial entorhinal layer II stellate cells have revealed subthreshold membrane potential oscillations (MPOs) whose temporal periods, and time constants of excitatory postsynaptic potentials (EPSPs), both increase along this axis. Slower (faster) subthreshold MPOs and slower (faster) EPSPs correlate with larger  grid spacings and field widths. A self-organizing map neural model explains how the anatomical gradient of grid spatial scales can be learned by cells that respond more slowly along the gradient to their inputs from stripe cells of multiple scales, which perform linear velocity path integration. The model cells also exhibit MPO frequencies that covary with their response rates. The gradient in intrinsic rhythmicity is thus not compelling evidence for oscillatory interference as a mechanism of grid cell firing. A response rate gradient combined with input stripe cells that have normalized receptive fields can reproduce all known spatial and temporal properties of grid cells along the MEC dorsoventral axis. This spatial gradient mechanism is homologous to a gradient mechanism for temporal learning in the lateral entorhinal cortex and its hippocampal projections. Spatial and temporal representations may hereby arise from homologous mechanisms, thereby embodying a mechanistic “neural relativity” that may clarify how episodic memories are learned.Place cells in the hippocampus of higher mammals are critical for spatial navigation. Recent modeling clarifies how this may be achieved by how grid cells in the medial entorhinal cortex (MEC) input to place cells. Grid cells exhibit hexagonal grid firing patterns across space in multiple spatial scales along the MEC dorsoventral axis. Signals from grid cells of multiple scales combine adaptively to activate place cells that represent much larger spaces than grid cells. But how do grid cells learn to fire at multiple positions that form a hexagonal grid, and with spatial scales that increase along the dorsoventral axis?  Spatial navigation is a critical competence of all higher mammals, and place cells in the hippocampus represent the large spaces in which they navigate. Recent modeling clarifies how this may occur via interactions between grid cells in the medial entorhinal cortex (MEC) and place cells. Grid cells exhibit hexagonal grid firing patterns across space and come in multiple spatial scales that increase along the dorsoventral axis of MEC. Signals from multiple scales of grid cells combine to activate place cells that represent much larger spaces than grid cells. This article shows how a gradient of cell response rates along the dorsoventral axis enables the learning of grid cells with the observed gradient of spatial scales as an animal navigates realistic trajectories. The observed gradient of grid cell membrane potential oscillation frequencies is shown to be a direct result of the gradient of response rates. This gradient mechanism for spatial learning is homologous to a gradient mechanism for temporal learning in the lateral entorhinal cortex and its hippocampal projections, thereby clarifying why both spatial and temporal representations are found in the entorhinal-hippocampal system. Navigating the world requires the brain to learn and maintain memory of spatial positions within various environments. Place cells in the hippocampal areas CA1 and CA3 demonstrate a neural code for position in large spaces that higher mammals inhabit In particular, Brun and colleagues The presence of multiple spatial scales on the dorsoventral axis of MEC has important implications for the development of the hippocampal place cells In vitro whole-cell patch clamp recordings Excitatory projections to the hippocampal formation from layer II of MEC are primarily from stellate cells This article develops a SOM neural model, called Spectral Spacing for reasons summarized below, to explain the above data. This model shows how a gradient of cell response rates along the dorsoventral axis of MEC can control the development of grid cells whose hexagonal grid firing fields exhibit a gradient of spatial scales and whose MPOs exhibit a gradient of frequencies. These results combine several conceptual and technical advances.First, these results are part of an emerging general entorhinal-hippocampal model architecture see also , which sSecond, these SOM laws have been proposed to control development and learning in many other parts of the brain, notably the visual cortex. Thus, both grid and place cells may develop using general SOM principles of brain map organization.Third, the linear velocity and angular velocity path integration inputs that drive model learning are derived from realistic trajectories of rats in spatial learning and memory experiments.Fourth, these linear velocity and angular velocity estimates can both be transformed into position codes by ring attractors.Fifth, the rate gradient mechanism for spatial learning in the MEC pathway and its hippocampal projections is homologous to a rate gradient mechanism that has been used to model temporal learning in the lateral entorhinal cortex (LEC) pathway and its hippocampal projections. Spatial and temporal representations in the medial and lateral processing streams may hereby arise from homologous mechanisms, thereby embodying a mechanistic “neural relativity” in the entorhinal-hippocampal system. This homology may clarify why spatial and temporal representations both occur in hippocampus, and provides new clues about how episodic memories may be learned.In summary, this model system exhibits parsimony and unity, both in its use of similar ring attractor mechanisms to code the linear and angular velocity path integration inputs that drive learning, and in its use of a rate gradient mechanism that can support the learning of both spatial and temporal codes.Even more striking is the fact that both grid cell and place cell receptive fields emerge by detecting, learning, and remembering the most frequent and energetic coactivations of their inputs. This co-occurrence property is different from the property of oscillatory interference that some other models have proposed e.g., . OscillaSimulation Settings). These simulations demonstrate that, at least among these variations, only a response rate gradient, combined with input cells that have normalized receptive fields, can explain all the data mentioned above.In order to better understand what aspects of the Spectral Spacing model are needed to explain how spatial and temporal properties of grid cell firing change along the dorsoventral extent of MEC, several model and input variations were simulated  and weight decreases (long-term depression). It hereby enables the weights to adapt to the Simultaneously active stripe cells are more likely to strongly activate map cells whose bottom-up weight patterns closely match their activity pattern. Adaptation of the weights to a map cell occurs only when its activity is above a threshold see  in . This poThe GRIDSmap model Until recently, SOM models of place cell learning used idealized or hand-crafted grid cells e.g., . Pilly aBoth the GRIDSmap and the GridPlaceMap models learn hexagonal grid firing fields whose spatial scale is derived from that of the input stripe cells. In particular, stripe cells with the same period were used to learn grid fields of a given spatial scale. Stripe cells of different spatial scales were assumed to activate different locations along the dorsoventral axis in layer II of MEC, thereby giving rise to grid cells with different spatial scales. But how is the selection of just one spatial scale of stripe cells realized for each grid cell scale? What would happen if stripe cells of multiple scales initially projected to the map layer before grid cell learning began, as in in vitro to a steady current input. Whereas a dorsoventral gradient in either response rate or habituation rate can explain the corresponding gradient in learned spatial scale and MPO frequency of grid cells, only a gradient in response rate was found to be consistent with data regarding the associated dorsoventral gradient in peak and mean firing rates of grid cells This article shows that the rates at which the category cells and their corresponding habituative transmitters respond, called the response rate . For a cell to respond with contrast-enhanced, or above-threshold, activity at any moment with the help of its self-excitatory feedback signal, its habituative transmitter needs to be at a sufficient high level. But each time the cell responds intensely, there is a collapse of the transmitter , which tThis property directly explains learned scale selectivity for the case of a rat running forward at a constant speed on a linear track. Then dorsal MEC cells in the model respond better to inputs at periodic positions with relatively smaller spacings, while ventral MEC cells respond better to those with relatively larger spacings. However, the situation is more complicated when the rat navigates along the type of two-dimensional real trajectory used in our simulations, for which the running speed of the rat through time varies between 0 cm/s and 146.6 cm/s with a mean of 14.03 cm/s, a standard deviation of 9.8 cm/s, and a mean length of piecewise linear segments of only 0.9 cm. How different response rates selectively learn different spatial scales in response to such realistic trajectories is discussed in the next subsection.Emergent properties of model simulations  emulate As noted earlier, for each input stripe scale considered separately, the most frequent and energetic activations of grid cells occur when sets of three stripe cells are coactivated whose preferred directions differ by 60° peak firing rate of MEC cells decreases from the dorsal to the ventral ends  exhibit lower gridness scores  and inte problem –7 is not problem  that wasells see . This reIn Case 8, unlike the data, dorsal cells learned hexagonal grid fields derived from large-scale stripe cells. This case imposes the same peak activity across both small-scale and large-scale stripe cells. Thus, the stripe cell receptive fields are not normalized across scales, and the large-scale stripe cells have a competitive advantage since they are sampled by map cells for a longer time. This advantage seems to be sufficient for them to win over small-scale stripe cells with the same peak activity, despite the lower frequency of their favored coactivations across space , in driving the learning of large-scale grid cells even for faster response rates. Thus, if stripe field widths increase with stripe spacing, similar to grid cells Normalized receptive fields occur in many other examples of multi-scale processing in the brain, and may be a general principle of brain design. The general design theme is how to achieve selective processing across multiple scales, so that the largest scales do not always win the competition to represent incoming data. Normalization ensures that the degree of brain commitment covaries with the amount of evidence for that choice gradient , and 7. gradient , in contin vitro studies have showed that layer II MEC stellate cells exhibit subthreshold MPOs, in response to steady current injection, whose temporal period increases from the dorsal to the ventral end of MEC  to convert a stripe cell population code that implicitly represents an animal's position using multiple small spatial scales into a place cell code in which a single place cell can explicitly represent spatial position in large environments. The intermediate stage of grid cells converts input stripe cell signals into a form conducive to the learning of such unimodal place cell spatial fields, which thereby significantly increase the scale of spatial representation compared to the inducing grid cells. Simulations in Can place cells be learned directly from stripe cells, without the intervention of hexagonal grid fields? The presence of the animal at a given spatial position strongly activates just one or few stripe cells in each directional ring attractor. So, a unimodal spatial field at that position could be learned, in principle, if a map cell could become tuned to the combination of all these coactive stripe cells across directions and scales. However, such input combinations are not favored by the self-organization process because they occur only at single positions in the environment, as opposed to the multiple positions at which the stripe cell combinations suitable for hexagonal grid fields are activated. As we mentioned above, map cell learning at both the grid cell and place cell levels is naturally sensitive to both the energy and frequency of input coactivations. How, then, are place cells learned, given they are activated only at single positions in the environment? If inputs to a SOM come from comprise grid cells of multiple spatial scales, then sets of co-active grid cells involving a greater number of scales are more likely to gain control of hippocampal map cells in vivo may be modulated by running speed, because of which the slope and intercept of the dorsal-ventral gradient in grid spacing may not be significantly altered in response to very fast or slow running speeds. It would be instructive to explicitly test this prediction.The spacings of grid fields in our model are adaptively selected based on cell response rate, which is inversely correlated with the minimum temporal duration between two episodes of intense activity. Therefore, it is important to discuss how the learned grid cells may respond if an adult animal were to run around an environment with a mean speed that is higher or lower than when the grid cells are learned during development. However, these extreme speed cases may be relevant only for theoretical purposes because of two reasons; namely, the distribution of running speeds in the realistic trajectory, used for our simulations, is relatively broadly tuned with a standard deviation of 9.8 cm/s, and existing relevant data indicates that the average running speed of rats increases by just ∼2 cm/s from P16 to adulthood . The nature of our model's incompleteness clarifies data about how and when deformations in grid cell receptive fields do occur In summary, our model here and in More work needs to be done to study how the response rate gradient and the habituative gating mechanism in our model relate to the HCN and leak potassium channels, which control the varied temporal integrative properties of MEC layer II stellate cells The model suggests several predictions regarding the development of grid cells at different anatomical locations along the dorsoventral axis of MEC as young animals begin to navigate for the first time. These predictions are tempered by the awareness that the model does not yet incorporate various known mechanisms, such as top-down matching and attentional mechanisms from hippocampus, that may influence model properties, notably their malleability after the predicted dynamical stabilization of grid field structures sets in due to attentive matching.Existing empirical studies on the development of grid cells The Spectral Spacing model illustrates how control by a single rate parameter can determine a gradient of grid cell spatial scales in response to inputs from multiple stripe cell spatial scales. Multiple small grid cell scales can then be adaptively combined in the hippocampus to generate place cell scales that are large enough to support spatial navigation In support of this prediction, MacDonald and coworkers Where cortical stream go through postrhinal cortex and medial entorhinal cortex on their way to hippocampal cortex, and object representations in the What cortical stream go through perirhinal cortex and lateral entorhinal cortex on their way to hippocampal cortex Thus, dorsoventral gradients in single rate parameters within the entorhinal-hippocampal system may create multiple small spatial and temporal scales that can be fused into larger spatial and temporal scales in the hippocampal cortex that are large enough to control adaptive behaviors. The mechanistic homology between these spatial and temporal mechanisms suggests why they may occur side-by-side in the medial and lateral streams through entorhinal cortex into the hippocampus. In particular, spatial representations in the This subsection highlights and justifies differences between the GRIDSmap model First, we introduced a threshold in the signal function that transforms membrane potentials of map cells into their output activities, which both govern the recurrent inhibitory interactions and gate the competitive adaptation of corresponding bottom-up weights .Increased stability of learned spatial fields as the bottom-up weights do not adapt in response to noisy or non-optimally activated map cells.Second, we initialized the pre-development synaptic weights of the connections from stripe cells to grid cells  in  using a Third, the inactivation and recovery dynamics of the habituative transmitter depend only on the self-excitatory feedback signal see  in the eFourth, the adaptive weights from stripe cells to category cells use a different version of the instar learning law (Equation 1.6) that more robustly enabled category cells to become tuned to coactivations of stripe cells In the GRIDSmap model, the stripe cells of different spacings were assumed to have the same maximal firing rate but different field widths (i.e., Several models exist to explain the generation of grid cells, but the Spectral Spacing model differentiates itself by providing for the first time a principled explanation of how grid cells learn not only their characteristic hexagonal grid firing patterns band cellsPrior grid cell models can be generally classified into two categories based on whether the linear velocity path integration happens before or at the level of grid cells. In addition to the SOM type of model, the former possibility has been modeled using mechanisms of oscillatory interference in vivo, result if this constraint is not met Oscillatory interference models The 2-D attractor models


The spectrum of HIV-associated neurocognitive disorder (HAND) has been dramatically altered in the setting of widely available effective antiretroviral therapy (ART). Once culminating in dementia in many individuals infected with HIV, HAND now typically manifests as more subtle, though still morbid, forms of cognitive impairment in persons surviving long-term with treated HIV infection. Despite the substantial improvement in severity of this disorder, the fact that neurologic injury persists despite ART remains a challenge to the community of patients, providers and investigators aiming to optimize quality of life for those living with HIV. Cognitive dysfunction in treated HIV may reflect early irreversible CNS injury accrued before ART is typically initiated, ongoing low-level CNS infection and progressive injury in the setting of ART, or comborbidities including effects of treatment which may confound the beneficial reduction in viral replication and immune activation effected by ART. More than 25 years after the initial recognition that HIV can directly damage the central nervous system (CNS) and lead to dementia , HIV-assCrucial processes in systemic HIV pathogenesis are initiated in acute and early HIV infection, including establishment of tissue HIV reservoirs, massive CD4 memory phenotype T cell loss, and establishment of viral and immune activation set points , 10. TheUntil recently, an understanding of the processes occurring in the CNS in the earliest stages of HIV infection have been informed almost entirely by animal models which allow for interrogation of the CNS after a known timing of initial lentiviral infection. In an accelerated rhesus macaque model of neuro-AIDS , CNS SIV10copies/ml in the CSF in one subject by 8 days post estimated infection. Taken together, data from these two cohorts suggest that HIV enters the CNS in the initial weeks after HIV exposure, but immune responses may control HIV RNA in the CSF in the early months of infection, in some individuals to undetectable levels , with median levels reduced to those measured in HIV-uninfected control subjects . HoweverThe overall concept that ART initiation prior to advanced immunosuppression may be beneficial to the CNS has been supported by observations that CD4 nadir is an important predictor of neurocognitive performance in treated subjects with chronic infection , 64. A rWhile classical HIV associated dementia (HAD) and progressive milder forms of disease may be presumed to be secondary to unchecked viral replication and inflammation within the CNS, HAND which persists or develops on ART is less well understood. The etiology of incident neurocognitive dysfunction in ART-suppressed patients is likely multifactorial, but may include poor access of ART to cells and tissues harboring HIV infection within the CNS, smoldering HIV infection which ‘escapes’ treatment and may be facilitated by immune activation, and potential antiretroviral toxicity in the nervous system.Due to barriers separating the peripheral circulation and the brain and CSF compartments, levels of antiretroviral drugs are reduced in CNS tissues, leading to speculation that systemically effective ART might fail to control CNS HIV infection. For the most part, ART appears to exert salutary effects in suppression of CSF HIV RNA and inflammation even when it fails to achieve peripheral viral control –68. SimiIn recognition of the fact that due to steric or molecular properties, certain antiretrovirals have decreased potential access to the CNS, Letendre and colleagues developed a CNS penetration-effectiveness (CPE) score to quantitate the putative CNS effects of each drug, taking into account to varied degrees the relative concentrations of each drug in CNS tissues, its ability to reduce CSF load, or affect dementia. Within each class of antiretrovirals, a CPE value is assigned to each drug, with higher values associated with presumed higher CNS effectiveness, and a total CPE score for a regimen calculated by adding the individual drug scores together , 71. Whi10 greater than plasma levels or >50 copies/ml where plasma levels are <50 copies/ml. CNS inflammation manifesting as CSF pleocytosis or increased CSF protein or albumin ratio is also typically associated, features not present in typical patients on ART. While some of these reports have included patients with very low CD4 counts or on monotherapy or salvage therapy, others have described symptomatic CSF escape in persons with reconstituted immune systems on standard regimens. Because of the progressive neurological dysfunction noted in the context of CSF to plasma ‘discordance’ with a pattern different from that in usual untreated or treated HIV, this syndrome has been referred to as ‘symptomatic CSF escape.’ These syndromes with manifest clinical neurologic disease are distinct from ‘asymptomatic CSF escape’ which is detected in a proportion of HIV-infected individuals undergoing lumbar puncture without symptoms and which has unclear clinical significance [For the vast majority of HIV-infected persons, systemically suppressive ART has resulted in apparent protection of the CNS from severe progressive neurologic disease, likely through a combination of reduced HIV replication within the CNS itself, reduced systemic as well as CNS immunoactivation, and reduced trafficking of immune cells as well as virally-infected cells to the nervous system. However, recent reports have drawn attention to the fact that in some rare cases, substantial HIV infection, inflammation, and clinical disease can evolve and manifest within the CNS in the setting of HIV treatment. In the most dramatic examples, patient can have relative immune preservation or reconstitution and undetectable plasma viral loads for prolonged periods, but still experience emergent CNS disorders. When explored carefully, the common features of patients with these conditions include stable ART therapy, well-controlled plasma viremia either to consistently undetectable levels or with low-level ‘blips,’ and new and progressive clinical signs and symptoms including new encephalopathy manifesting as dementia or aphasia, often accompanied by tremor, ataxia, severe headache, or sensory changes ••, 82–86ificance .Though the lack of suppression of CSF HIV RNA is a hallmark of the syndrome, the pathogenesis most likely involves not only the CSF and meninges, but the brain parenchyma itself, based on the clinical manifestations of the disorder, neuroimaging which has been reported in several cases to demonstrate patterns suggestive of cerebral inflammation, and brain pathology which indicates CD8 T lymphocyte infiltration and widespread inflammation. Indeed, these syndromes are likely on a continuum with newly described cases of ‘CD8 T cell encephalitis’ in which patients with incident and progressive dementia or clinical encephalitis have been noted to have dramatic infiltration of CD8 T lymphocytes on biopsy with imaging and CSF evidence of inflammation as well as low-level detectable CSF HIV •, 88. ThBoth symptomatic CSF escape and CD8 encephalitis are likely related to ongoing CNS infection in the CNS compartment in the context of a substrate of CNS inflammation, usually in the context of a relatively reconstituted immune system. In many described cases, genotyping of CSF yields a distinct resistance pattern in the CNS compartment from that present in plasma, or evidence of resistance to drugs which successfully suppress plasma virus. This suggests that one contributor to persistent HIV production in these disorders may be compartmentalization of HIV strains within the CNS, perhaps facilitated by poor CNS exposure of ART or by prior inconsistent medication adherence. Additionally, the presence of elevated CNS inflammation in symptomatic CSF escape and CD8 encephalitis may directly lead to enhanced production of HIV locally within CNS tissues, as inflammatory signals lead to increased trafficking of infected cells, as well as target cells of infection, to the CNS. Many patients with these disorders have been reported to have clinical improvement when ART regimens are tailored both to address resistance genotypes detected in the CSF as well as to improve presumed blood brain barrier penetration. For this reason, knowledge of these syndromes is critical to the HIV provider and patient, since substantial clinical improvement or even complete resolution of symptoms may result from proper diagnosis and treatment intervention. Additionally, recognition that such conditions can exist provides proof for the concept that a biologically meaningful reservoir for HIV infection may exist in the CNS even in the setting of treatment. In one report, CSF escape was accompanied by recrudescence of low-level plasma viremia, which was hypothesized to possibly have resulted from ‘reseeding’ of the successfully treated periphery from the CNS compartment . A numbein vitro models that have unclear clinico-pathologic significance [A substantial controversy in the field of neuroAIDS is whether antiretroviral therapy may be directly toxic to the nervous system and itself contribute to HAND. Though numerous studies and epidemiological observations have demonstrated the major beneficial effects of effective ART for the CNS, one study demonstrated improvement in neuropsychological testing performance in a cohort of 167 HIV infected persons interrupting therapy . Though ificance , 93.Individual agents have potential or observed adverse effects on the CNS. The most dramatic example of these is the NNRTI efavirenz, which has a broad array of cognitive and behavioral effects including insomnia and vivid dreaming, daytime encephalopathy, fatigue, hallucinations, irritability, increased anxiety and suicidality. Though most of these effects are at their peak in the first weeks after initiating therapy, many persist long term and are a central reason for discontinuing or switching efavirenz-containing regimens . Not onlDespite the widespread use of ART and its proven effectiveness in preventing classical HIV-associated dementia, a substantial proportion of HIV infected individuals meet criteria for HAND ••, 7, 8.


There is considerable theoretical and empirical support for a link between substance misuse and perpetration and victimization of intimate partner violence. This review briefly summarizes this literature and highlights current research that addresses the interface between treatment for substance abuse and intimate partner violence. Suggestions for future research and clinical implications are provided. The prevalence and frequency of intimate partner violence (IPV) is a major public health concern. In a large study evaluating couples in the United States, over one-fifth of the sample reported experiencing IPV within the past year.4IPV may be perpetrated by either gender. In a meta-analytic study, Archer12A major hurdle to studying and treating partner violence is the heterogeneity of the perpetrators and victims. Researchers have hypothesized that there may be subtypes of partner violent men or couples, with a different etiology of violence for each subtype.There is an abundance of theoretical and empirical support for a connection between substance misuse and intimate partner violence perpetration and victimization. For example, a number of theorists have proposed etiological models of IPV in which the substance misuse of both partners plays an important role.29Numerous other theories have been proposed to explain the relationship between substance use and intimate partner violence perpetration. Theoretical models such as the spurious model, the indirect effects model, and the proximal effects model have been used to account for the association between IPV and substance use, with varying amounts of empirical support.32Empirical studies have demonstrated a strong association between the use of a variety of substances and IPV perpetration and victimization, with a majority of the research focusing on alcohol.42We have been conducting cross-sectional and longitudinal research on the association between substance misuse and IPV in our laboratory for many years. In order to address enduring questions regarding the associations between substance misuse and IPV, we have, with some exceptions,A number of studies have shown that the prevalence of IPV perpetration and victimization in treatment-seeking samples of male and female substance abusers is extremely high .To test this central hypothesis, we have conducted several longitudinal studies examining the impact of treatment for substance abuse on IPV perpetration and victimization. All patients in our studies were diagnosed with alcohol abuse or dependence, and many had comorbid drug diagnoses. Substance abuse treatment involved a 5–6 day intensive outpatient partial hospitalization program, which had a cognitive-behavioral orientation administered primarily in a group format. Our research has shown significant reductions in substance use, IPV perpetration, and IPV victimization in menNumerous studies have demonstrated that couples-based treatment approaches for addictions65Consistent with past research, we have found that menResearch has suggested that batterer intervention programs designed to reduce IPV recidivism have poor efficacy.77plus standard batterer intervention or standard batterer intervention alone. We are assessing substance use, alcohol related problems, and IPV perpetration and victimization at baseline, 3-, 6-, and 12-month follow-up. We hypothesize that adding a brief alcohol treatment to standard batterer intervention will result in less alcohol use and less IPV perpetration and victimization at all follow-up assessments, relative to standard batterer intervention alone.In light of these data, we are currently conducting a randomized clinical trial in which hazardous drinking men arrested for domestic violence perpetration and court referred to batterer intervention programs are assigned to either a brief, motivationally focused alcohol intervention Preliminary data from this study appear promising. Relative to standard batterer intervention alone, participants receiving the additional brief alcohol treatment evidence superior outcomes at one or more follow-up points in frequency of drinking, percentage of heavy drinking days, drinks per drinking day, and percentage of days abstinent from alcohol and drugs. In addition, men receiving the brief alcohol treatment have reported significantly reduced psychological and sexual aggression perpetration, relative to standard batterer intervention alone. Our research group has just begun conducting a similar randomized clinical trial with hazardous drinking women arrested for domestic violence. Our long-term goal is to establish the efficacy of the adjunct brief alcohol treatment and examine its effectiveness in reducing substance use, as well as IPV perpetration and victimization, in batterer programs across the United States.Given the role of substance use in risk for IPV perpetration and victimization, there appears to be a critical role for brief interventions targeting substance use in high IPV-risk populations. Our work with individuals who have been arrested for IPV perpetration represents an early step in targeting substance use to impact IPV recidivism, and there are several other domains where similar interventions may also have a wide-reaching impact. With regard to generalizability, it would be useful to determine the extent to which the efficacy of brief interventions are limited to intimate partner violence, or whether they might transfer to other populations and other forms of interpersonal violence. For example, brief substance use interventions may be transported to populations at high risk for violence such as individuals who are incarcerated or recently released from incarceration. Additionally, substance use interventions might be effectively combined with other treatments, including parent training to more effectively decrease risk for child abuse while concurrently enhancing positive parent-child interactions. Another promising area for future research might involve increasing the specificity of our appreciation of the parameters within which brief interventions are effective for reducing violence perpetration and victimization. Specifically, several studies have determined the heterogeneity of IPV perpetrators


Diarrhea is a leading cause of morbidity among children under 5 years of age in low- and middle-income countries yet the additional effects and sequelae, such as cognitive impairment associated with diarrhea, have not been quantified.We quantified the association between diarrhea prevalence and cognitive outcomes while controlling for linear growth in 4 study populations. Cognition was assessed using different methods across sites and was expressed in standardized units. We built linear regression models for each study with standardized cognitive score as the outcome and diarrhea prevalence as the main predictor variable. We then conducted meta-analyses of the regression coefficients to generate pooled estimates of the association between diarrhea prevalence and cognition whilst controlling for anthropometric status and other covariates.Diarrhea was not a significant predictor of cognitive score in any site in the regression models or in the meta-analyses . The length for age Z- score was negatively related to cognition in all sites , with coefficients remarkably similar across sites (Coefficient Range: 0.168–0.186).We did not demonstrate an association between diarrhea and cognition with stunting included in the model. The links between diarrhea, stunting, and cognition provide additional rationale for accelerating interventions to reduce diarrhea. Diarrhea is a leading cause of morbidity and mortality among children under 5 years of age in low- and middle-income countries Frequent diarrhea during the first 2 years of life has been negatively correlated with cognitive development and early school performance There is also evidence suggesting that cognitive delays may be related to differences in caregiver behavior toward a sickly child. During the acute and convalescent period of an illness, the child may be listless and less eager to play or explore his/her environment We sought to quantify the association of diarrhea on cognitive outcomes while controlling for stunting in 4 datasets from 4 distinct study populations. Published studies have found an association between diarrhea and cognition, but often do not take into consideration anthropometric status diarrhea, stunting, length-for-age, growth, cognitive impairment, cognition, and children. We searched for studies that conducted routine diarrhea surveillance among populations of children under 2 years of age for at least 1 year, collected anthropometric indicators and conducted a follow-up of cognitive development at least 1 year after the initial diarrhea surveillance period. We excluded studies that did not use a published methodology for assessing cognition.We conducted a PubMed search to identify possible studies for inclusion using the following search terms: We sought to determine if diarrhea prevalence between 0 and 2 years of age had an impact on cognitive development later in life controlling for stunting at 2 years. To do this we built linear regression models for each study and subsequently conducted meta-analyses to pool each of the beta coefficients produced by these regressions. In the selected studies, cognitive scores were reported using 4 different methodologies and scales: non-verbal IQ For each study, we fitted two regression models with the standardized cognitive score as the outcome and diarrhea prevalence, defined as the percentage of days/study periods in which the caregiver reported diarrhea, as the main predictor variable. Model 1 controlled for length-for-age (LAZ) at age 2 as a continuous variable and model 2 controlled for LAZ as a categorical variable (with LAZ ≤−2 as a the cut off for stunted vs. not stunted). LAZ was defined by the World Health Organization reference standard We conducted meta-analyses to pool regression beta coefficients for variables with exact definitions across all four regression models . In order to generate pooled estimates of regression beta coefficients, we used Comprehensive Meta Analysis (CMA) software, which requires the coefficient and its standard error We identified four studies that met our inclusion and exclusion criteria. The studies were conducted among 4 pediatric populations in low-income settings with ongoing diarrhea surveillance; details of the studies have been previously published We conducted linear regression models for each study site to determine the within study effect, if any, of diarrhea on cognition. Diarrhea was not a significant predictor of cognitive score in any site . The LAZWe then conducted meta-analyses to pool the regression coefficients across study sites and thus determine the cross-country effect of diarrhea on cognition whilst controlling for anthropometric status. The results of the two models were similar; here we present the pooled results of model 1 which considered length-for-age Z score as a continuous variable . In poolWe conducted a meta-analysis to assess the relationship between diarrhea and cognition while controlling for LAZ. We included 4 data sets from 4 different study populations and did not see an overall effect of diarrhea prevalence rates during the first 2 years of life on cognitive scores several years later. We did not observe an association of diarrhea prevalence and cognitive scores yet we did observe a remarkably consistent association of LAZ score and cognitive development across data sites. Thus, in these data sets a portion of cognitive impairment might be explained by the child's length deficit and this is independent of the child's diarrhea prevalence rate. It may be possible that diarrhea is a contributing factor to childhood stunting in these low-income settings but in this setting diarrhea prevalence alone did not appear to be associated with poorer cognitive performance in these children.Some studies have observed associations between increasing diarrhea prevalence rates during early childhood and deficits or delays in later cognition Our analysis has several potential methodological weaknesses. The studies included here assessed cognition with 4 distinct methodologies. These studies were not designed with this meta-analysis in mind; rather, they were designed to use the best-standardized cognitive test available, which could be locally adapted to each setting. We accounted for the differences in scoring practices by using a statistically standardized score for each regression; this enabled us to include all study sites in the meta-analysis, even though the outcome variables were scaled differently. The studies included here also had variable follow-up time and did not have standard socio-economic covariates. Though we accounted for these differences analytically, the analysis would have been stronger if these covariates were standard across the datasets.We included age in the regression model for all countries. Although cognitive test scores are age standardized, the standardization method differs among tests, and thus including this variable enabled us to control for residual confounding. In Philippines and Brazil, we observed a residual effect of age. In the Philippines, older children scored higher on the cognitive tests above and beyond what is accounted for in age-standardized test scores. However, in Brazil we observed a negative relationship between age at testing and cognitive performance. This may reflect increasing disparities over time such that children who demonstrate more advanced cognitive abilities early on and who live in stimulating environments continue to progress while children who have a lower skill level and are raised in non-stimulating environments fail to progress The complex pathways by which nutrition, infection, and the home environment affect a child's development are not well understood. Although there are limited data suggesting that numerous factors are at play, few studies have been able to look at all factors thus the roles of each remain elusive. Berkman et al observed that nutrition, parental education and school related factors independently affected cognition, but similar literature is scarce We did not demonstrate an association between diarrhea on cognition. Stunting remained a statistically significant covariate in this analysis showing a remarkably homogeneous association and suggesting a consistent relationship between stunting and cognition. While diarrhea may not directly impact cognitive impairment, the links between diarrhea and stunting, and stunting and cognition are clear and provide additional rationale for accelerating interventions to reduce diarrhea.


The availability of Next Generation Sequencing tools has uncovered an unexpected and highly complex universe of hidden microbial passengers that are transiently or permanently associated with their hosts, hereafter called symbionts. Under natural conditions, these symbionts are often tightly controlled to occur at low densities and/or are restricted to special tissues by intrinsic and extrinsic factors, such as their own replication capacity, nutrition, and stress, as well as host immune competence.PLOS Genetics, Luis Teixeira and colleagues Wolbachia, one of the most intensively studied symbionts. Wolbachia are found in up to 70% of insect species and in many terrestrial arthropods, and are vertically transmitted with the egg from an infected female to her progeny. In order to enhance their spreading success throughout host populations, Wolbachia can manipulate host reproductive biology by acting as a reproductive parasite, enhancing fitness and fecundity of infected females, enabling them to outcompete uninfected females rapidly in nature One of the main questions of current symbiosis research is, however, to what extent these microbial passengers affect host phenotypes such as fitness, fecundity, pathogen resistance, or even behavior. In this issue of Wolbachia have changed their phenotype from reproductive parasitism to obligate mutualism, where the symbiont takes on essential host functions for, e.g., oogenesis, nutrition, or even mate recognition Wolbachia can transform from a costly reproductive parasite into a mutualist by enhancing fecundity of infected Drosophila simulans females But what happens to the infection as soon as the majority of individuals within a host population are already infected and the spreading of the bacteria comes to a stop? In some cases it has been shown that, in their evolutionary past, Wolbachia strain named wMelCS with the closely related variant wMel in Drosophila melanogaster, the top genetic model system for studying insect host-symbiont interactions Wolbachia strain causes any significant level of reproductive parasitism in its respective native host, either in the laboratory or in nature, both persist globally in D. melanogaster at high frequencies worldwide, suggesting they serve some host functions. Moreover, two independent studies have shown that both Wolbachia strains confer significant virus protection D. melanogaster Wolbachia also protects artificially transinfected mosquitos that do not naturally carry Wolbachia from pathogenic RNA viruses, such as Dengue and Chikungunya Wolbachia strain of D. melanogaster that provides even stronger virus resistance is wMelPop, a pathogenic Wolbachia variant that originally emerged after radiation mutagenesis in the laboratory. This virulent Wolbachia strain has recently become a major research focus because it overreplicates massively in somatic host tissues (it is named “popcorn” due to the popcorn-like appearance of infected cells in adult tissues) and hence significantly shortens the lifespan of its host Aedes aegypti, it was shown that the life-shortening effect of wMelPop is also manifest in this medically important insect system D. melanogaster Wolbachia strains prime candidates for biologically sound insect pest control strategies. Besides their impressive applied capacities for arthropod-borne disease control, however, we currently lack understanding on the following main questions: what are the genotypic and phenotypic differences between the three strains, and why did the wMel strain replace wMelCS globally in the recent past? A better understanding of their genetic basis and their short-term cost–benefit dynamics will be pivotal for further Wolbachia-applied studies in heterologous pest systems.One of the most puzzling observations, however, is the worldwide replacement during the 20th century of one ancestral Wolbachia dynamics in D. melanogaster. First, they crossed the three Wolbachia variants wMelCS, wMel, and wMelPop into a common genetic fly background in order to exclude any nuclear background effects. Then they carefully assayed for their capacity to suppress viral infections of the Drosophila C virus and Flock house virus in the presence and absence of Wolbachia. They found that the ancestral wMelCS variants proliferate to higher densities and confer greater protection against the two RNA viruses than do flies infected with wMel variants. They also found that flies carrying the ancestral wMelCS infection, although more protected against viral infections, pay a price by living slightly shorter lives than wMel-infected flies (Wolbachia variant wMel, which still protects the host significantly from viral infections but replicates at lower densities with lower costs on longevity.To this end, Texeira and colleagues studied the molecular and phenotypic basis of short-term ed flies . They thWolbachia group. Through their thoughtful comparative analysis of mutualistic wMelCS-like versus pathogenic wMelPop genomes, they found that these two phenotypically distinct Wolbachia strains form a monophyletic group that mainly differ in only one genomic region: a 7-fold amplification of a 21-kb region in wMelPop encoding eight Wolbachia proteins. These data strongly imply that the selective amplification of one or more genes within this so-called “Octomom region” is quite likely responsible for the expression of the virulent Popcorn phenotype.Finally, they trace the genetic basis for the transition from symbiosis to virulence by linking phenotype to genotype in the monophyletic wMelCS Wolbachia pathogenicity? What are the genetic bases for symbiont-directed viral host protection and its strength? And finally, what kind of phenotypic and genetic Wolbachia transitions can be expected to happen in novel host systems such as mosquitos in the near future under natural selection? Stay tuned! It is likely that we are pretty close to monitoring short-term evolutionary dynamics of host–symbiont interactions in real time.This impressive study opens numerous additional questions that will be highly relevant for symbiosis research but also for future applied aspects: Which of the eight candidate genes of the Octomom region of wMelPop are sufficient for triggering


The link between natural disasters and subsequent fungal infections in disaster-affected persons has been increasingly recognized. Fungal respiratory conditions associated with disasters include coccidioidomycosis, and fungi are among several organisms that can cause near-drowning pneumonia. Wound contamination with organic matter can lead to post-disaster skin and soft tissue fungal infections, notably mucormycosis. The role of climate change in the environmental growth, distribution, and dispersal mechanisms of pathogenic fungi is not fully understood; however, ongoing climate change could lead to increased disaster-associated fungal infections. Fungal infections are an often-overlooked clinical and public health issue, and increased awareness by health care providers, public health professionals, and community members regarding disaster-associated fungal infections is needed. The potential for adverse health events after natural disasters is well recognized and comprises various challenges for public health  are well defined, but others (such as Aspergillus and other molds) are thought to be ubiquitous. The abundance and distribution  of environmental fungi probably depend on climatic or environmental factors such as ambient temperature and moisture , and in 4 (10.5%) of 38 wound isolates from 23 ambulatory patients  is hypothesized to be the most common fungal pathogen associated with near-drowning, although this finding has not been studied specifically in the context of disasters    in 1 tourist , which resolved without antifungal treatment (Syncephalastrum was detected in various clinical specimens from 8 persons whose self-reported exposures to mold ranged from none to heavy, but none had evidence of invasive infection (Few data clearly demonstrate that indoor mold exposures increase the risk for invasive infection in post-disaster settings. Flooding lasted for weeks after Hurricanes Katrina and Rita made landfall on the US Gulf Coast in August and September 2005, respectively, leading to visible mold growth in 46% of 112 inspected homes (Aspergillus fumigatus, A. flavus, and basidiomycetous fungi; culture plates exposed inside the refuge showed a similar fungal profile, suggesting that the indoor environment may have played a role in the patients’ infections (After the 2011 Great East Japan Earthquake and subsequent tsunami, a medical relief team observed unexplained chronic cough among a group of previously healthy persons living in a temporary refuge (Cryptococcus gattii, to expand into areas that are currently more temperate (Climate change could be affecting the ecology of pathogenic fungi in ways that are not yet fully understood; even minor or gradual changes in temperature, moisture, and wind patterns might affect fungal growth, distribution, and dispersal (Huppert and Sparks suggest that global climate change is contributing to greater frequency and severity of extreme weather events and that current patterns of population growth, urbanization, and human activity create conditions that render many communities increasingly vulnerable to these hazards (Disasters are complex events that can result in a wide range of health effects, although infectious disease outbreaks as an immediate consequence of disasters are uncommon. Health care providers should be aware of the possibility for cases or clusters of community-acquired or health care–associated fungal infections among disaster survivors because these infections often appear clinically similar to bacterial infections and can be associated with serious illness and death. These infections can occur in persons who do not have the typical immunocompromising risk factors for fungal infection but who have experienced near-drowning, trauma, or other unusual exposure to the environment, such as a dust storm. A fungal infection should be considered early if a patient has a persistent or progressive infection that is not responding to initial antibacterial treatment, particularly because rapid diagnosis and administration of appropriate antifungal therapy can improve patient outcomes. Prompt restoration of disaster-affected aspects of the local health care infrastructure may help facilitate earlier diagnosis and treatment and possibly reduce the risk for infection associated with the use of contaminated medical equipment or substandard care. Strategies to reduce disaster-associated fungal infections should be considered within the broader context of comprehensive and sustainable risk reduction methods to prevent disaster-related injury and illness.