Robust movement direction decoders from local field potentials using spatio-temporal qualitative patterns
permalink2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society - 2012-08-28Tadipatri VA, Tewfik AH, Ashe J, Pellizzer G10.1109/EMBC.2012.6346997A major drawback of using Local Field Potentials (LFP) for Brain Computer Interface (BCI) is their inherent instability and non-stationarity. Specifically, even when a well-trained subject performs the same task over a period of time, the neural data observed are unstable. To overcome this problem in decoding movement direction, this paper proposes the use of qualitative information in the form of spatial patterns of inter-channel ranking of multi-channel LFP recordings. The quality of the decoding was further refined by concentrating on the statistical distributions of the top powered channels. Decoding of movement direction was performed using Support Vector Machines (SVM) to construct decoders, instead of the traditional spatial patterns. Our algorithm provides a decoding power of up to 74% on average over a period of two weeks, compared with the state-of-the-art methods in the literature that yield only 33%. Furthermore, it provides 62.5% direction decoding in novel motor environments, compared with...
Canonical correlation analysis of Synchronous Neural Interactions and cognitive deficits in Alzheimer's dementia
permalinkJournal of Neural Engineering - 2012-08-07Karageorgiou E, Lewis S, McCarten JR, Leuthold A, Hemmy LS, McPherson SE, Rottunda SJ, Rubins D, Georgopoulos AP10.1088/1741-2560/9/5/056003In previous work (Georgopoulos et al 2007 J. Neural Eng. 4 349-55) we reported on the use of magnetoencephalographic (
Synchronous Neural Interactionsas a functional biomarker in Alzheimer's dementia (AD) diagnosis. Here we report on the application of canonical correlation analysis to investigate the relations between
SNIand cognitive neuropsychological (NP) domains in AD patients. First, we performed individual correlations between each
SNIand each NP, which provided an initial link between
SNIand specific cognitive tests. Next, we performed factor analysis on each set, followed by a canonical correlation analysis between the derived
SNIand NP factors. This last analysis optimally associated the entire
MEGsignal with cognitive function. The results revealed that
SNIas a whole were mostly associated with memory and language, and, slightly less, executive function, processing speed and visuospatial abilities, thus differentiating functions subserved by the frontoparietal and the temporal cortices. These findings provide...
Religious distress and coping with stressful life events: a longitudinal study.
The War Against Posttraumatic Stress Disorder
permalinkMinnesota Monthly - 2012-06-21From the article:
How one machine and two Minnesota researchers are forever changing the stigma surrounding Post-Traumatic Stress DisorderApostolos Georgopoulos looks like a brain scientist. Animated, friendly, and crowned with a mane of flyaway gray hair, he shakes my hand and ushers me into his office. He immediately offers to make me coffee, then, in the next breath, insists I sit in the throne situated next to the window-a gift he received for being a Regents professor of neuroscience at the University of Minnesota. "Isn't it something?" he says enthusiastically. "I don't even know how they got it in here!" ...
How Complex are neural interactions?
An Exploratory Examination of Risk-Taking Behavior and Posttraumatic Stress Disorder Symptom Severity in a Veteran Sample
Executive Control Over Cognition: Stronger and Earlier Rule-Based Modulation of Spatial Category Signals in Prefrontal Cortex Relative to Parietal Cortex
permalinkJournal of Neuroscience - 2012-03-07Goodwin SJ, Blackman R, Sakellaridi S, Chafee M10.1523/JNEUROSCI.3585-11.2012Human cognition is characterized by flexibility, the ability to select not only which action but which cognitive process to engage to best achieve the current behavioral objective. The ability to tailor information processing in the brain to rules, goals, or context is typically referred to as executive control, and although there is consensus that prefrontal cortex is importantly involved, at present we have an incomplete understanding of how computational flexibility is implemented at the level of prefrontal neurons and networks. To better understand the neural mechanisms of computational flexibility, we simultaneously recorded the electrical activity of groups of single neurons within prefrontal and posterior parietal cortex of monkeys performing a task that required executive control of spatial cognitive processing. In this task, monkeys applied different spatial categorization rules to reassign the same set of visual stimuli to alternative categories on a trial-by-trial basis. We found that single neurons were activated to...
The Minnesota Women Healthy Aging Project
Types of Workplace Social Support in the Prediction of Job Satisfaction
Neuropsychological Testing and Structural Magnetic Resonance Imaging as Diagnostic Biomarkers Early in the Course of Schizophrenia and Related Psychoses
permalinkNeuroinformatics - 2011-12-01Karageorgiou E, Schulz SC, Gollub RL, Andreasen NC, Ho BC, Lauriello J, Calhoun VD, Bockholt, Sponheim S, Georgopoulos AP10.1007/s12021-010-9094-6Making an accurate diagnosis of schizophrenia and related psychoses early in the course of the disease is important for initiating treatment and counseling patients and families. In this study, we developed classification models for early disease diagnosis using structural MRI (
Structural Magnetic Resonance Imaging) and neuropsychological (NP) testing. We used
sMRImeasurements and NP test results from 28 patients with recent-onset schizophrenia and 47 healthy subjects, drawn from the larger sample of the Mind Clinical Imaging Consortium. We developed diagnostic models based on Linear Discriminant Analysis (LDA) following two approaches; namely, (a) stepwise (STP) LDA on the original measurements, and (b) LDA on variables created through Principal Component Analysis (PCA) and selected using the Humphrey-Ilgen parallel analysis. Error estimation of the modeling algorithms was evaluated by leave-one-out external cross-validation. These analyses were performed on
sMRIand NP variables separately and in combination. The following classification accuracy was obtained for different variables and modeling algorithms....
Top-down spatial categorization signal from prefrontal to posterior parietal cortex in the primate
permalinkFrontiers in Systems Neuroscience - 2011-08-24Merchant H, Crowe D, Robertson MS, Fortes A, Georgopoulos AP10.3389/fnsys.2011.00069In the present study we characterized the strength and time course of category-selective responses in prefrontal cortex and area 7a of the posterior parietal cortex during a match-to-sample spatial categorization task. A monkey was trained to categorize whether the height of a horizontal sample bar, presented in rectangular frame at one of three vertical locations, was "high" or "low," depending on whether its position was above or below the frame's midline. After the display of this sample bar, and after a delay, choice bars were sequentially flashed in two locations: at the top and at the bottom of the frame ("choice" epoch). If the monkey timed its response to the display of the choice bar that matched the sample bar, he was rewarded. We found that cells in prefrontal cortex discriminated category early after the initial sample bar was shown, and continued to differentiate "up" from "down" trials throughout the delay...
Disrupted functional connectivity for controlled visual processing as a basis for impaired spatial working memory in schizophrenia
permalinkNeuropsychologia - 2011-08-01Kang SS, Sponheim S, Chafee M, MacDonald III AW10.1016/j.neuropsychologia.2011.06.009Although regional brain abnormalities underlying spatial working memory (SWM) deficits in schizophrenia have been identified, little is known about which brain circuits are functionally disrupted in the SWM network in schizophrenia. We investigated SWM-related interregional functional connectivity in schizophrenia using
Functional Magnetic Resonance Imagingdata collected during a memory task that required analysis of spatial information in object structure. Twelve schizophrenia patients and 11 normal control subjects participated. Patients had SWM performance deficits and deficient neural activation in various brain areas, especially in the high SWM load condition. Examination of the covariation of regional brain activations elicited by the SWM task revealed evidence of functional disconnection between prefrontal and posterior visual association areas in schizophrenia. Under low SMW load, we found reduced functional associations between dorsolateral prefrontal cortex (DLPFC) and inferior temporal cortex (ITC) in the right hemisphere in patients. Under high SWM load, we found evidence for further functional...
True associations between resting Functional Magnetic Resonance Imaging time series based on innovations
permalinkJournal of Neural Engineering - 2011-06-29Christova P, Lewis S, Jerde T, Lynch J, Georgopoulos AP10.1088/1741-2560/8/4/046025We calculated voxel-by-voxel pairwise crosscorrelations between prewhitened resting-state BOLD
fMRItime series recorded from 60 cortical areas (30 per hemisphere) in 18 human subjects (nine women and nine men). Altogether, more than a billion-and-a-quarter pairs of BOLD time series were analyzed. For each pair, a crosscorrelogram was computed by calculating 21 crosscorrelations, namely at zero lag ± 10 lags of 2 s duration each. For each crosscorrelogram, in turn, the crosscorrelation with the highest absolute value was found and its sign, value, and lag were retained for further analysis. In addition, the crosscorrelations at zero lag (irrespective of the location of the peak) were also analyzed as a special case. Based on known varying density of anatomical connectivity, we distinguished four general brain groups for which we derived summary statistics of crosscorrelations between voxels within an area (group I), between voxels of paired homotopic areas across the two hemispheres (group II),...
Movement direction decoding of local field potentials using time-evolving spatial patterns
The effectiveness of a trauma focused spiritually integrated intervention for veterans exposed to trauma
permalinkJournal of Clinical Psychology - 2011-02-03Harris JI, Erbes CR, Engdahl B, Thuras P, Murray-Swank N, Grace D, Ogden H, Olson RHA, Winskowski AM, Bacon R, Malec C, Campion K, Le T10.1002/jclp.20777Building Spiritual Strength (BSS) is an 8-session, spiritually integrated group intervention designed to address religious strain and enhance religious meaning making for military trauma survivors. It is based upon empirical research on the relationship between spirituality and adjustment to trauma. To assess the intervention's effectiveness, veterans with histories of trauma who volunteered for the study were randomly assigned to a BSS group (n = 26) or a wait-list control group (n = 28). BSS participants showed statistically significant reductions in
Posttraumatic Stress Disordersymptoms based on self-report measures as compared with those in a wait-list control condition. Further research on spiritually integrated interventions for trauma survivors is warranted.
Differential brain activity states during the perception and nonperception of illusory motion as revealed by magnetoencephalography
High Accuracy Decoding of Movement Target Direction in Non-Human Primates Based on Common Spatial Patterns of Local Field Potentials
permalinkPLoS ONE - 2010-12-21Ince NF, Gupta R, Arica S, Tewfik AH, Ashe J, Pellizzer G10.1371/journal.pone.0014384BackgroundThe current development of brain-machine interface technology is limited, among other factors, by concerns about the long-term stability of single- and multi-unit neural signals. In addition, the understanding of the relation between potentially more stable neural signals, such as local field potentials, and motor behavior is still in its early stages.Methodology/Principal FindingsWe tested the hypothesis that spatial correlation patterns of neural data can be used to decode movement target direction. In particular, we examined local field potentials (LFP), which are thought to be more stable over time than single unit activity (SUA). Using LFP recordings from chronically implanted electrodes in the dorsal premotor and primary motor cortex of non-human primates trained to make arm movements in different directions, we made the following observations: (i) it is possible to decode movement target direction with high fidelity from the spatial correlation patterns of neural activity in both primary motor (M1) and dorsal premotor...
U of M working to help veterans with Posttraumatic Stress Disorder
PTSD), which often affects veterans.
Coping Functions of Prayer and Posttraumatic Growth
Post-traumatic stress disorder: a right temporal lobe syndrome?
permalinkJournal of Neural Engineering - 2010-10-28Engdahl B, Leuthold A, Tan HRM, Lewis S, Winskowski AM, Dikel TN, Georgopoulos AP10.1088/1741-2560/7/6/066005In a recent paper (Georgopoulos et al 2010 J. Neural Eng. 7 016011) we reported on the power of the
SNItest to differentiate post-traumatic stress disorder (
PTSD) subjects from healthy control subjects and to classify them with a high degree of accuracy. Here we show that the main differences in cortical communication circuitry between these two groups lie in the miscommunication of temporal and parietal and/or parieto-occipital right hemispheric areas with other brain areas. This lateralized temporal-posterior pattern of miscommunication was very similar but was attenuated in patients with
PTSDin remission. These findings are consistent with observations (Penfield 1958 Proc. Natl Acad. Sci. USA 44 51-66, Penfield and Perot 1963 Brain 86 595-696, Gloor 1990 Brain 113 1673-94, Banceaud et al 1994 Brain 117 71-90, Fried 1997 J. Neuropsychiatry Clin. Neurosci. 9 420-8) that electrical stimulation of the temporal cortex in awake human subjects,...