Systems Neuroscience Commons^™

Firing Rate Dynamics In Recurrent Spiking Neural Networks With Intrinsic And Network Heterogeneity, Cheng Ly

Statistical Sciences and Operations Research Publications

Heterogeneity of neural attributes has recently gained a lot of attention and is increasing recognized as a crucial feature in neural processing. Despite its importance, this physiological feature has traditionally been neglected in theoretical studies of cortical neural networks. Thus, there is still a lot unknown about the consequences of cellular and circuit heterogeneity in spiking neural networks. In particular, combining network or synaptic heterogeneity and intrinsic heterogeneity has yet to be considered systematically despite the fact that both are known to exist and likely have significant roles in neural network dynamics. In a canonical recurrent spiking neural network model, …

Clique Topology Reveals Intrinsic Geometric Structure In Neural Correlations, Chad Giusti, Eva Pastalkova, Carina Curto, Vladimir Itskov

Department of Mathematics: Faculty Publications

Detecting meaningful structure in neural activity and connectivity data is challenging in the presence of hidden nonlinearities, where traditional eigenvalue-based methods may be misleading. We introduce a novel approach to matrix analysis, called clique topology, that extracts features of the data invariant under nonlinear monotone transformations. These features can be used to detect both random and geometric structure, and depend only on the relative ordering of matrix entries. We then analyzed the activity of pyramidal neurons in rat hippocampus, recorded while the animal was exploring a 2D environment, and confirmed that our method is able to detect geometric organization using …

Reducing Subjectivity: Meditation And Implicit Bias, Diana M. Ciuca

CMC Senior Theses

Implicit association of racial stereotypes is brought about by social conditioning (Greenwald & Krieger, 2006). This conditioning can be explained by attractor networks (Sharp, 2011). Reducing implicit bias through meditation can show the effectiveness of reducing the rigidity of attractor networks, thereby reducing subjectivity. Mindfulness meditation has shown to reduce bias from the use of one single guided session conducted before performing an Implicit Association Test (Lueke & Gibson, 2015). Attachment to socially conditioned racial bias should become less prevalent through practicing meditation over time. An experimental model is proposed to test this claim along with a reconceptualization of consciousness …

Characterizing The Temporal Dynamics In Functional Connectivity Measured With Fmri, Joshua Swearingen

MUSC Theses and Dissertations

There is a considerable and growing interest in the organization and development of neural function at the scale of the entire brain, particularly from activity observed in fluctuations in the blood oxygen level dependent (BOLD) signal in functional magnetic resonance imaging (fMRI). This activity reliably organizes into sub-networks, whether obtained from subjects at rest or from those involved in various perceptual or cognitive tasks. While these networks have often been identified and studied, the precise dynamics involved in their interactions as well as the relationship between organization found in both resting and task-based activity are not well understood. Here I …

Influence Of Planning Resources On Gait Control In Parkinson’S Disease, Frederico P. Faria

Theses and Dissertations (Comprehensive)

Movement disturbances in individuals with Parkinson’s disease (PD) have been associated with difficulties to plan complex actions. Performance of simple and complex actions overloads resources for individuals with Parkinson’s disease (PD). However, it is unclear if central resources required to plan gait adjustments while walking exacerbate gait disturbances of patients with PD. More specifically, it is unclear how gait impairments, sensory processing, and the dopaminergic system influence the load on processing resources (e.g. cognitive load) during the planning of step modifications. In order to investigate the relative influence of these factors on cognitive load and its impact on gait control, …

A Principle Of Economy Predicts The Functional Architecture Of Grid Cells, Xue-Xin Wei, Jason Prentice, Vijay Balasubramanian

Publications and Research

Grid cells in the brain respond when an animal occupies a periodic lattice of ‘grid fields’ during navigation. Grids are organized in modules with different periodicity. We propose that the grid system implements a hierarchical code for space that economizes the number of neurons required to encode location with a given resolution across a range equal to the largest period. This theory predicts that (i) grid fields should lie on a triangular lattice, (ii) grid scales should follow a geometric progression, (iii) the ratio between adjacent grid scales should be √e for idealized neurons, and lie between 1.4 and 1.7 …

Dementia And Primary-Care Health Measures:Hearing, Gait, And Markers Of Inflammation, Elsa Lindgren

Honors Theses and Capstones

Dementia is a syndrome associated with declining cognitive function that has a variety of types and causes, and is encountered frequently in general medical practice. Researchers are actively exploring possible risk factors for dementia. The St. Louis University Mental Status (SLUMS) exam is a dementia-screening exam used in primary care visits to detect cognitive impairment that may be a sign of dementia. This study compared scores on the SLUMS exam to other measures recorded in a typical primary care visit in 86 patients of age 65 and older to look for correlations between indicators of health, such as physical examination …

Effects Of Resting State On Perceptual Learning, Sarah Eagleman Ph.D.

Dissertations and Theses (Open Access)

Psychophysical experiments in humans have demonstrated that improvements in perceptual learning tasks occur following daytime rests. The neural correlates of how rest influences subsequent sensory processing during these tasks remain unclear. One possible neural mechanism that may underlie this behavioral improvement is reactivation. Previously evoked network activity reoccurs – reactivates - in the absence of further stimulation. Reactivation was initially discovered in the hippocampus but has now been found in several brain areas including cortex. This phenomenon has been implicated as a general mechanism by which neural networks learn and store sensory information. However, whether reactivation occurs in areas relevant …

An Introduction To Drugs And The Neuroscience Of Behavior, Adam J. Prus

Books

This up-to-date text provides an introductory overview of the nervous system actions and behavioral effects of the major classes of psychoactive drugs, using pedagogy unique among pharmacology texts to make the topic approachable.

Dopaminergic And Activity-Dependent Modulation Of Mechanosensory Responses In Drosophila Melanogaster Larvae, Josh S. Titlow

Theses and Dissertations--Biology

A central theme of this dissertation is nervous system plasticity. Activity-dependent plasticity and dopaminergic modulation are two processes by which neural circuits adapt their function to developmental and environmental changes. These processes are involved in basic cognitive functions and can contribute to neurological disorder. An important goal in modern neurobiology is understanding how genotypic variation influences plasticity, and leveraging the quantitative genetics resources in model organisms is a valuable component of this endeavor. To this end I investigated activity-dependent plasticity and dopaminergic modulation in Drosophila melanogaster larvae using neurobiological and genetic approaches.

Larval mechanosensory behavior is described in Chapter 2. …

A Systems Biology Approach To Detect Eqtls Associated With Mirna And Mrna Co-Expression Networks In The Nucleus Accumbens Of Chronic Alcoholic Patients, Mohammed Mamdani

Theses and Dissertations

Alcohol Dependence (AD) is a chronic substance use disorder with moderate heritability (60%). Linkage and genome-wide association studies (GWAS) have implicated a number of loci; however, the molecular mechanisms underlying AD are unclear. Advances in systems biology allow genome-wide expression data to be integrated with genetic data to detect expression quantitative trait loci (eQTL), polymorphisms that regulate gene expression levels, influence phenotypes and are significantly enriched among validated genetic signals for many commonly studied traits including AD.

We integrated genome-wide mRNA and miRNA expression data with genotypic data from the nucleus accumbens (NAc), a major addiction-related brain region, of 36 …

Variance Predicts Salience In Central Sensory Processing, Ann M. Hermundstad, John J. Briguglio, Mary M. Conte, Jonathan D. Victor, Vijay Balasubramanian, Gašper Tkačik

Publications and Research

Information processing in the sensory periphery is shaped by natural stimulus statistics. In the periphery, a transmission bottleneck constrains performance; thus efficient coding implies that natural signal components with a predictably wider range should be compressed. In a different regime—when sampling limitations constrain performance—efficient coding implies that more resources should be allocated to informative features that are more variable. We propose that this regime is relevant for sensory cortex when it extracts complex features from limited numbers of sensory samples. To test this prediction, we use central visual processing as a model: we show that visual sensitivity for local multi-point …

Neural Correlates Of Audiovisual Speech Perception In Aphasia And Healthy Aging, Sarah H. Baum

Dissertations and Theses (Open Access)

Understanding speech in face-to-face conversation utilizes the integration of multiple pieces of information, most importantly the auditory vocal sounds and visual lip movements. Prior studies of the neural underpinnings of audiovisual integration in the brain have provided converging evidence to suggest that neurons within the left superior temporal sulcus (STS) provide a critical neural hub for the integration of auditory and visual information in speech. While most studies of audiovisual processing focus on neural mechanisms within healthy, young adults, we currently know very little about how changes to the brain can affect audiovisual integration in speech. To examine this further, …

The Expanding Genomic Landscape Of Autism: Discovering The 'Forest' Beyond The 'Trees', Valerie Wailin Hu

Biochemistry and Molecular Medicine Faculty Publications

Autism spectrum disorders (ASDs) are neurodevelopmental disorders characterized by significant deficits in reciprocal social interactions, impaired communication, and restricted, repetitive behaviors. Because ASDs are among the most heritable of neuropsychiatric disorders, much of autism research has focused on the search for genetic variants in protein-coding genes (i.e., the "trees"). However, no single gene can account for more than 1% of the cases of ASD. Yet, genome-wide association studies have often identified statistically significant associations of genetic variations in regions of DNA that do not code for proteins (i.e., intergenic regions). There is increasing evidence that such noncoding regions are actively …

The Effect Of Visual Wulst Lesions And Trigeminal Nerve Sectioning On The Discrimination Of Magnetic Inclination In The Homing Pigeon (Columba Livia), Merissa Acerbi

Honors Projects

The ability of homing pigeons to return to their loft from unknown places has fascinated scientists for centuries. It is well established that homing pigeons, like migratory birds, posses an innate magnetic inclination compass to determine direction by measuring the angle between the magnetic field vector and the Earth's surface. Recent work has indicated that the avian magnetic compass is light mediated and appears to mediate magnetic information to the brain. This occurs via a visual pathway with processing in the visual Wulst area of the forebrain. There is, however, also evidence from other avian species that magnetic direction may …

Effects Of Head Position And Head-Supported Mass On Nerve Function Of The Flexor Carpi Radialis Muscle In Healthy Individuals, Bethany Lauren Shivers

Graduate Theses and Dissertations

Long-term exposure to head-supported mass (HSM) has been linked with spinal degeneration including foraminal stenosis and disc deterioration. Anecdotally, HSM has also been linked to neck and arm pain and muscle atrophy, but nerve function has not been tested specifically. The combined effect of various head positions and HSM may be sufficient to compress the nerve root in aviators and Soldiers during job performance, potentially leading to short- and long-term neuromuscular effects. The Hoffmann (H) reflex, a well-established measure of nerve function, has shown to be sensitive to changes in nerve root space which occurs with different head positions. This …

Loss Of Circuits Promoting Appetite Are Associated With Increases In Circuits Promoting Satiety: Where Is The Plasticity Occurring?, Nicole Dominguez, Ellen M. Walker, Arshad M. Khan*

COURI Symposium Abstracts, Summer 2012

Hindbrain catecholamine (CA) neurons promote feeding, whereas arcuate hypothalamic alpha melanocyte-stimulating hormone (αMSH) neurons promote satiety. A key brain region receiving these CA feeding and αMSH satiety signals is the paraventricular hypothalamus (PVH). We have observed that the αMSH inputs unexpectedly increase if the feeding-promoting CA inputs are lesioned. Here, we asked whether the increased αMSH inputs reflect altered numbers of αMSH neurons in the arcuate hypothalamus after the lesion or represent only local changes at the level of the PVH. Immunofluorescently labeled ARH αMSH neurons from 28 control and lesioned rats were counted as follows: confocal images from left …

Population Coding In Laminar Cortical Circuits, Bryan J. Hansen

Dissertations and Theses (Open Access)

One of the fundamental questions in neuroscience is to understand how encoding of sensory inputs is distributed across neuronal networks in cerebral cortex to influence sensory processing and behavioral performance. The fact that the structure of neuronal networks is organized according to cortical layers raises the possibility that sensory information could be processed differently in distinct layers. The goal of my thesis research is to understand how laminar circuits encode information in their population activity, how the properties of the population code adapt to changes in visual input, and how population coding influences behavioral performance. To this end, we performed …

Chemoarchitecture Of Hindbrain Autonomic Nuclei: Contiguous Mapping And Distribution Of Six Biomarkers In The Adult Male Rat, Sarah D. Chenausky^, Arshad M. Khan*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Angioarchitecture Of The Adult Rat Neuroendocrine Hypothalamus, Nicolas D. Silva^, Arshad M. Khan*

COURI Symposium Abstracts, Spring 2012

No abstract provided.