Brain Sciences Center - News

Departure from Network Equilibrium (DNE): an efficient and scalable measure of instantaneous network dynamics, with an application to magnetoencephalography

The assessment of the dynamic status of a network is currently unavailable. It is important to know how far a network is away from its equilibrium (as an indicator of instability) at a moment, and over periods of time. Here, we introduce the Departure from Network Equilibrium (DNE), a new measure of instantaneous network dynamics. DNE is simple, fast to compute, and scalable with network size. We present the results of its application on white noise networks (as a basis) and on networks derived from magnetoencephalographic recordings from the human brain.

Magnetization transfer and adiabatic T1ρ MRI reveal abnormalities in normal-appearing white matter of subjects with multiple sclerosis

Background:Diffuse abnormalities are known to occur within the brain tissue of multiple sclerosis (MS) patients that is "normal appearing" on T1-weighted and T2-weighted magnetic resonance images.Objectives:With the goal of exploring the sensitivity of novel MRI parameters to detect such abnormalities, we implemented an inversion-prepared magnetization transfer (MT) protocol and adiabatic T1ρ and T2ρ rotating frame relaxation methods.Methods:Nine relapsing-remitting MS patients and seven healthy controls were recruited. Relaxation parameters were measured in a single slice just above the lateral ventricles and approximately parallel to the AC-PC line.Results:The MT ratio of regions encompassing the normal-appearing white matter (NAWM) was different in MS patients as compared with controls (p = 0.043); however, the T1 measured during off-resonance irradiation (T1sat) was substantially more sensitive than the MT ratio for detecting differences between groups (p = 0.0006). Adiabatic T1ρ was significantly prolonged in the NAWM of MS patents as compared to controls (by 6%, p =...
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UofM researcher appointed Anderson Chair in Post-traumatic Stress DisorderPost-traumatic Stress Disorder (PTSD)A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern. Research

Brian Engdahl, Ph.D., a professor of neuroscience, cognitive science, and psychology at the at the University of Minnesota and psychologist and clinician investigator at the Minneapolis , has been appointed the Anderson Chair in Research at the University of Minnesota Medical School.The Anderson Chair helps understand and heal the psychological scars that often haunt veterans as they return home from service. The $2 million gift honors the late William Lewis Anderson, a combat medic who died trying to save a wounded soldier on the battlefield in World War II.Engdahl has served veterans for more than 30 years at the and Minneapolis and is working on numerous research initiatives to assess and treat veterans with serious disabilities, including ."It's an honor to be named the Anderson Chair in Research," said Engdahl. "We hope to continue the...
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University of Minnesota researcher appointed Anderson Chair in Post-traumatic Stress DisorderPost-traumatic Stress Disorder (PTSD)A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern. Research

Brian Engdahl, Ph.D., a professor of neuroscience, cognitive science, and psychology at the at the University of Minnesota and psychologist and clinician investigator at the Minneapolis , has been appointed the Anderson Chair in Research at the University of Minnesota Medical School.The Anderson Chair helps understand and heal the psychological scars that often haunt veterans as they return home from service. The $2 million gift honors the late William Lewis Anderson, a combat medic who died trying to save a wounded soldier on the battlefield in World War II.

Prefrontal neurons transmit signals to parietal neurons that reflect executive control of cognition

Prefrontal cortex influences behavior largely through its connections with other association cortices; however, the nature of the information conveyed by prefrontal output signals and what effect these signals have on computations performed by target structures is largely unknown. To address these questions, we simultaneously recorded the activity of neurons in prefrontal and posterior parietal cortices of monkeys performing a rule-based spatial categorization task. Parietal cortex receives direct prefrontal input, and parietal neurons, like their prefrontal counterparts, exhibit signals that reflect rule-based cognitive processing in this task. By analyzing rapid fluctuations in the cognitive information encoded by activity in the two areas, we obtained evidence that signals reflecting rule-dependent categories were selectively transmitted in a top-down direction from prefrontal to parietal neurons, suggesting that prefrontal output is important for the executive control of distributed cognitive processing.

The trail of trauma

When a disaster strikes, groups of people spontaneously form and start talking all at once.And your brain does the same thing in response to personal trauma. Groups of neurons in the cerebral cortex start firing at the same time, "talking" to each other, and get locked into a correlated pattern of activity. Previous work by University of Minnesota researchers identified a particular pattern so strongly associated with that they can clearly tell who has . Now, a new study shows that in people with , these patterns persist, just as do the intrusive, incapacitating memories or re-experiencing of the events, emotional numbing, and hyperarousal that define the disorder.But, they found, in people who have not developed despite exposure to trauma, the patterns lack staying power. In them, "these patterns loosen and dissipate over weeks, months, or days," says lead researcher Lisa James, an assistant professor in...
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In dragonflies, descending visual neurons code prey direction in population vector form

The population vector is the weighted vectorial sum activity of an ensemble of neurons and it was first shown to predict the direction of an upcoming arm movement in monkeys (Georgopoulos et al. 1983, 1986). In this study we show that in the dragonfly Libellula luctuosa, the population vector algorithm also decodes the target direction information relayed from the brain to the wing motor centers by a group of 16 neurons. Moreover, these 16 neurons (named Target Selective Descending Neurons or TSDNs; Olberg 1986), perform such directional information coding with high accuracy across 360°. This is significant because the monkey motor cortex requires upwards of 200 neurons to achieve the same performance (Georgopoulos et al. 1988). To obtain the TSDNs directional tuning curves, we impaled a total of 51 TSDNs from 38 animals with sharp electrodes and recorded their responses to a battery of 3497 target trajectories. The target had a...
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Source localization techniques for direction decoding from local field potentials

Local Field Potential (LFP) recordings are one type of intracortical recordings, (besides Single Unit Activity) that can help decode movement direction successfully. In the longterm however, using LFPs for decoding presents some major challenges like inherent instability and non-stationarity. Our approach to overcome this challenge bases around the hypothesis that each task has a signature source-location pattern. The methodology involves introduction of source localization, and tracking of sources over a period of time that enables us to decode movement direction in an eight-direction center-out-reach-task. We establish that such tracking can be used for long term decoding, with preliminary results indicating consistent patterns. In fact, tracking task related source locations render up to 66% accuracy in decoding movement direction one week after the decoding model was learnt.

Acquisition of Rater Agreement for the Stressful Life Events Schedule

Stress has been linked to a broad range of psychopathology including alcohol and drug dependence. Recent advances in our understanding of how stress interacts with biological systems involved in addiction has generated even greater interest in stress assessment among addiction researchers. The Stressful Life Events Schedule (SLES) capitalizes on the strengths and avoids the pitfalls of self-report checklist and interview-based stress assessments. Because the SLES depends on consensus ratings of a research team, this study examined rater agreement of stressful event ratings across the first year using the SLES. Individual ratings of stressful events were compared between two experienced and three new raters. Ratings were analyzed for life events generated from interviews of 70 adolescent psychiatric inpatients and 62 healthy adolescents. Inexperienced raters, with backgrounds in addiction research, reliably rated stressful events and rater agreement improved over a year's time. Recommendations for successfully adopting the SLES for consensus rating are discussed.

Effects of Ketamine on Context-Processing Performance in Monkeys: A New Animal Model of Cognitive Deficits in Schizophrenia

Cognitive deficits are at the crux of why many schizophrenia patients have poor functional outcomes. One of the cognitive symptoms experienced by schizophrenia patients is a deficit in context processing, the ability to use contextual information stored in working memory to adaptively respond to subsequent stimuli. As such, context processing can be thought of as the intersection between working memory and executive control. Although deficits in context processing have been extensively characterized by neuropsychological testing in schizophrenia patients, they have never been effectively translated to an animal model of the disease. To bridge that gap, we trained monkeys to perform the same dot pattern expectancy (DPX) task, which has been used to measure context-processing deficits in human patients with schizophrenia. In the DPX task, the first stimulus in each trial provides the contextual information that subjects must remember in order to appropriately respond to the second stimulus in the trial. We...
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The number of cysteine residues per mole in Apolipoprotein EApolipoprotein E (ApoE)a plasma lipoprotein discovered in 1973 (Shore and Shore 1973). It binds low-density lipoprotein receptors, thereby facilitating cellular lipoprotein exchange and metabolism. The human apoE polypeptide consists of 299 amino acids and comprises three polymorphisms resulting from single amino acid substitutions. Three isoforms (E4, E3, and E2) are the result of cysteine^aEUR"arginine interchanges at two sites, namely residues 112 and 158; however, other genetic variants have been described. These three isoforms, each differentially affecting protein function, result in six phenotypes: three homozygotes (E4/4, E3/3, E2/2) and three heterozygotes (E4/3, E4/2, E3/2). With respect to the number of cysteine residues per mole, E2/2 contains 4, E3/2 contains 3, E4/2 and E3/3 each contain 2, E4/3 contains 1, and E4/4 contains 0. The number of cysteine residues per mole (CysR/mole) provides a numerical, biochemical scale in lieu of the genotype-based categories. affects systematically Synchronous Neural InteractionsSynchronous Neural Interactions (SNI)Zero-lag partial correlations in pairs of MEG time series and denote the strength and polarity (positive or negative) of neuronal interactions. Anomalies in SNIs as assessed by MEG differentiate psychiatric disorders from healthy brain functioning and can discriminate among various brain diseases. From this research, a highly distinctive, unique PTSD SNI signature characterized by miscommunication of temporal and parietal and/or parieto-occipital right hemispheric areas with other brain areas has emerged. These findings, in addition to the growing research applying MEG to other psychiatric disorders, highlight the utility of MEG in identifying biomarkers of disease and underscore the potential for broader clinical applications of MEG. in women's healthy brains

is involved in lipid metabolism in the brain, but its effects on brain function are not understood. Three isoforms (E4, E3, and E2) are the result of cysteine-arginine interchanges at two sites: there are zero interchanges in E4, one interchange in E3, and two interchanges in E2. The resulting six genotypes (E4/4, E4/3, E4/2, E3/3, E3/2, E2/2) yield five groups with respect to the number of cysteine residues per mole (CysR/mole), as follows. 4/4 has zero cysteine residues per mole (0-CysR/mole), E4/3 has one (1-CysR/mole), E4/2 and E3/3 each has two (2-CysR/mole), E3/2 has three (3-CysR/mole), and E2/2 has four (4-CysR/mole). The use of the number of CysR/mole to characterize the molecule converts the categorical genotype scale, consisting of 6 distinct genotypes above, to a 5-point continuous scale (0-4 CysR/mole). This allows the use of statistical analyses suitable for continuous variables (e.g. regression) to...
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Impulsivity modulates performance under response uncertainty in a reaching task

We sought to explore the interaction of the impulsivity trait with response uncertainty. To this end, we used a reaching task (Pellizzer and Hedges in Exp Brain Res 150:276-289, 2003) where a motor response direction was cued at different levels of uncertainty (1 cue, i.e., no uncertainty, 2 cues or 3 cues). Data from 95 healthy adults (54 F, 41 M) were analysed. Impulsivity was measured using the Barratt Impulsiveness Scale version 11 (BIS-11). Behavioral variables recorded were reaction time (RT), errors of commission (referred to as 'early errors') and errors of precision. Data analysis employed generalised linear mixed models and generalised additive mixed models. For the early errors, there was an interaction of impulsivity with uncertainty and gender, with increased errors for high impulsivity in the one-cue condition for women and the three-cue condition for men. There was no effect of impulsivity on precision errors or RT. However, the analysis...
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Mpls. VA brain research examines resilience to trauma

From MPR's coverage of the research from the

New research from the Minneapolis VAMCVA Medical Center (VAMC) has identified brain patterns that appear to be markers of resilience to trauma. The findings could suggest why some people exposed to trauma develop PTSDPost-traumatic Stress Disorder (PTSD)A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern., or PTSDPost-traumatic Stress Disorder (PTSD)A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern., while many others do not.Researchers say the findings, published online Wednesday in the journal JAMA Psychiatry, point to a central mechanism showing how the brain can recover from traumatic events. ...

Risk and Protective Factors Associated With Symptoms of Post-Traumatic Stress, Depression, and Alcohol Misuse in Operation Enduring Freedom - AfghanistanOperation Enduring Freedom - Afghanistan (OEF)The U.S. government used the term "Operation Enduring Freedom - Afghanistan" (OEF) to officially describe the War in Afghanistan, from the period between October 2001 and December 2014. ... Continued operations in Afghanistan by the United States' military forces, both non-combat and combat, now occur under the name "Operation Freedom's Sentinel"./Operation Iraqi FreedomOperation Iraqi Freedom (OIF)The period of the Iraq war lasting from 2003 to 2010 was referred to as Operation Iraqi Freedom (OIF) by the United States military. The conflict is also known as the War in Iraq, the Occupation of Iraq, the Second Gulf War, Gulf War II, and Gulf War 2. Veterans

Military personnel returning from the conflicts in Iraq and Afghanistan commonly experience mental health problems and efforts are underway to determine risk and protective factors associated with postdeployment mental health concerns. This study examined the contribution of trait neuroticism, predeployment life events, combat experience, perceptions of threat, and postdeployment social support on mental health symptoms at 6 months, 12 months, and 24 months postdeployment. Two hundred seventy-one veterans completed self-report measures. Hierarchical regression analyses demonstrated that neuroticism predicted post-traumatic stress and depressive symptoms at all 3 time points; perceived threat predicted post-traumatic stress symptoms at Time 1 and Time 2 and depressive symptoms at Time 2. Social support was a strong negative predictor of post-traumatic stress and depressive symptoms. Alcohol misuse was not significantly predicted by any of the variables. The present study highlights the role of perceived threat and trait neuroticism on postdeployment mental health symptoms and indicates social support...
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Thinking in spatial terms: decoupling spatial representation from sensorimotor control in monkey posterior parietal areas 7a and LIP

Perhaps the simplest and most complete description of the cerebral cortex is that it is a sensorimotor controller whose primary purpose is to represent stimuli and movements, and adaptively control the mapping between them. However, in order to think, the cerebral cortex has to generate patterns of neuronal activity that encode abstract, generalized information independently of ongoing sensorimotor events. A critical question confronting cognitive systems neuroscience at present therefore is how neural signals encoding abstract information emerge within the sensorimotor control networks of the brain. In this review, we approach that question in the context of the neural representation of space in posterior parietal cortex of non-human primates. We describe evidence indicating that parietal cortex generates a hierarchy of spatial representations with three basic levels: including (1) sensorimotor signals that are tightly coupled to stimuli or movements, (2) sensorimotor signals modified in strength or timing to mediate cognition (examples include attention,...
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A Scalar Neural Code for Categories in Parietal Cortex: Representing Cognitive Variables as "More" or "Less"

In this issue, Fitzgerald et al. (2013) show that LIP neurons in monkeys encode categorically distinct task conditions using a scalar code. Activity scales up or down to encode different categories, with neurons maintaining proportional levels of activity in relation to one another.

Neural Network Modulation by Trauma as a Marker of Resilience Differences Between Veterans With Posttraumatic Stress Disorder and Resilient Controls

Importance Posttraumatic stress disorder () and resilience reflect 2 distinct outcomes after exposure to potentially traumatic events. The neural mechanisms underlying these different outcomes are not well understood.Objective To examine the effect of trauma on for veterans with and resilient controls using magnetoencephalography.Design Participants underwent diagnostic interviews, a measure of exposure to potentially traumatic events, and magnetoencephalography.Setting US Department of Veterans Affairs medical center.Participants Eighty-six veterans with and 113 resilient control veterans recruited from a large Midwestern medical center.Main Outcome Measures Multiple regression analyses were performed to examine the effect of lifetime trauma on global and local . In analyses examining the local , the partial regression coefficient indicates the strength and direction of the effect of trauma on the synchronous interactions between the 2 neural signals recorded by a pair of sensors. The partial regression coefficient, or slope, is the primary...
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Exploring small city maps

The exploration of city maps has exploded recently due to the wide availability, increasing use of, and reliance on small positioning and navigational devices for personal use. In this study, subjects explored small, 3-mile diameter circular maps exemplifying five different types of street networks common in the United States, in order to locate a hypothetical city hall. Chosen locations indicated that subjects are able to identify more accessible sites. Monitoring eye position revealed that women explored maps faster, using more widely dispersed but more narrowly focused gaze clusters than men. The type of street network influenced the time spent by the eyes in a locale and differentially affected the size of gaze clusters between women and men, underscoring the complex interactions of gender-specific strategies with street network types.

Spatiotemporal neural interactions underlying continuous drawing movements as revealed by magnetoencephalography

Continuous and sequential movements are controlled by widely distributed brain regions. A series of studies have contributed to understanding the functional role of these regions in a variety of visuomotor tasks. However, little is known about the neural interactions underpinning continuous movements. In the current study, we examine the spatiotemporal neural interactions underlying continuous drawing movements and the association of them with behavioral components. We conducted an experiment in which subjects copied a pentagon continuously for ~45 s using an XY joystick, while neuromagnetic fluxes were recorded from their head using a 248-sensor whole-head device. Each sensor time series was rendered stationary and non-autocorrelated by applying an autoregressive integrated moving average model and taking the residuals. We used the directional variability of the movement as a behavioral measure of the controls generated. The main objective of this study was to assess the relation between neural interactions and the variability...
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A compact and realistic cerebral cortical layout derived from prewhitened resting-state Functional Magnetic Resonance ImagingFunctional Magnetic Resonance Imaging (fMRI)A functional neuroimaging procedure using MRI technology that measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases.[citation needed] The primary form of fMRI uses the blood-oxygen-level dependent (BOLD) contrast, discovered by Seiji Ogawa. This is a type of specialized brain and body scan used to map neural activity in the brain or spinal cord of humans or other animals by imaging the change in blood flow (hemodynamic response) related to energy use by brain cells. Since the early 1990s, fMRI has come to dominate brain mapping research because it does not require people to undergo shots, surgery, or to ingest substances, or be exposed to ionising radiation, etc. time series: Cherniak's adjacency rule, size law, and metamodule grouping upheld

We used hierarchical tree clustering to derive a functional organizational chart of 52 human cortical areas (26 per hemisphere) from zero-lag correlations calculated between single-voxel, prewhitened, resting-state BOLD time series in 18 subjects. No special "resting-state networks" were identified. There were four major features in the resulting tree (dendrogram). First, there was a strong clustering of homotopic, left-right hemispheric areas. Second, cortical areas were concatenated in multiple, partially overlapping clusters. Third, the arrangement of the areas revealed a layout that closely resembled the actual layout of the cerebral cortex, namely an orderly progression from anterior to posterior. And fourth, the layout of the cortical areas in the tree conformed to principles of efficient, compact layout of components proposed by Cherniak. Since the tree was derived on the basis of the strength of neural correlations, these results document an orderly relation between functional interactions and layout, i.e., between structure and function.