Systems Neuroscience Commons^™

Invisible Shipwrecks And Neurological Endangerment: The Trade-Off In Seeking Asylum - Reframing The Neurobiological Cost Of Forced Migration, Eisha Giran

CISLA Senior Integrative Projects

Forced migration along the Spain–Morocco route represents one of the most visible humanitarian crises of the twenty-first century, yet its neurological dimensions remain insufficiently examined. This paper investigates how prolonged displacement and trauma reshape neural systems involved in stress regulation, memory, and emotional processing. It introduces the concept of neurological endangerment, defined as a condition of prolonged and inescapable threat exposure during forced migration in which stress-response systems remain chronically activated, opportunities for recovery are structurally constrained, and cumulative neurobiological risk persists beyond the period of immediate danger.

To address the gap between biological measurement and lived experience, this paper …

Neural Mechanisms Underlying Jung’S Active Imagination: A Review And Hypothesis, Charles R. Fox

Journal of Conscious Evolution

Active imagination is a key technique of Jungian analysis. Despite its centrality, and its potential importance beyond Jungian psychology to the area of systems neuroscience, psychology, and consciousness studies, there are no known neurological mechanisms underlying this psychological phenomenon. There is a history of using the types of mental imagery used in active imagination to explore consciousness. The development and use of active imagination is briefly reviewed, and a case is developed that the neurology underlying active imagination would be fruitfully explored by considering it a special case of mystical experience. Active imagination primarily uses the right hemisphere processing of …

Circuit And Synaptic Mechanisms Of Methamphetamine Induced Cognitive Deficits During Abstinence: Roles Of The Perirhinal-Prefrontal Pathway And The Nucleus Reuniens, Sarah Goldsmith

MUSC Theses and Dissertations

Cognitive deficits during abstinence are a hallmark of methamphetamine (meth) use and indicative of negative treatment outcomes. In rats, both long access meth self-administration and meth binge produce recognition memory deficits due to drug-induced plasticity within the perirhinal cortex (PRH). PRH projections are numerous and include the medial prefrontal cortex (mPFC) and the Nucleus Reuniens (NRe). In the first study, the role of the PRH-mPFC reciprocal circuit in novel object recognition memory was investigated by infusing an rgAAV encoding GFP-tagged Cre recombinase into the PRH or the mPFC. Following surgery, rats explored objects. During exploration, PRH neurons receiving input from …

Assessing The Effects Of Theta Transcranial Alternating Current Stimulation During Working Memory Performance On Theta-Gamma Phase Amplitude Coupling In Healthy Adults, Samantha M. Zimmer

UNF Graduate Theses and Dissertations

Transcranial alternating current stimulation (tACS) is an emerging form of noninvasive brain stimulation with substantial effects on behavior and brain function due to its ability to entrain endogenous neural oscillations. Working memory is a cognitive process that involves holding onto information that is no longer present in the environment and manipulating or reorganizing information for immediate use. Theta oscillations are critical for the functionality of the frontoparietal network and are involved in strengthening communication and coordination between frontal and parietal brain regions, especially during working memory processing. TACS applied at the theta frequency, targets theta oscillations, strengthens network communications, and …

Neural Dynamics Supporting Flexible Cognition, Meredith J. Mccarty

Dissertations and Theses (Open Access)

Flexible cognition enables humans to adapt their behavior to changing circumstances by prioritizing relevant information and filtering out distractions. This process is thought to be supported by the integration of ongoing behavioral goals with incoming sensory information, but how this integration is realized in the human brain remains unclear. It is unknown how high-order sensory cortices can balance specialized processing with flexible integration of changing behavioral goals. In the following investigations, we use intracranial EEG (iEEG) recordings in humans to study the neural dynamics of flexible cognition during high-order sensory processing. First, we validated assumptions about the locality of iEEG …

The Science Of Sound: Studying The Cognitive, Emotional, And Physiological Effects Of Frequency, Genre, And Music, Jett Yarborough

Senior Honors Theses

Music influences emotion, physiology, and cognition, yet little is known about how the frequency it is tuned to affects these influences. Prior research has shown that music tuned to 432 Hz can reduce stress, lower blood pressure, and improve sleep. My colleagues and I conducted two studies to investigate this. Our research found that music tuned to 432 Hz promotes a significant increase in memory retention and induces a state of focus and relaxation. These results suggest that shifting from the standard tuning frequency of 440 Hz to 432 Hz could have a profoundly positive impact on our daily lives. …

Memory Interference In The Lateral Entorhinal Cortex, Omar Ghazy

Dissertations, Theses, and Capstone Projects

Memory interference occurs when previously formed memories disrupt the acquisition or retrieval of new information. A prominent example of proactive interference is latent inhibition (LI), defined as a reduced ability to form or express Pavlovian associations with a stimulus following non-reinforced exposure. The interference-based model suggests that LI arises because the memory that the pre-exposed stimulus is inconsequential interferes with the memory that it predicts a reinforcer.

Because interference increases with age, identifying its neural basis may help prevent or slow cognitive decline. Prior studies using the LI paradigm implicate the entorhinal cortex (EC) in retrieving the memory that a …

Neural Activity Within And Between Visual And Executive Areas Is Modulated Post-Locomotion In Rhesus Macaques, Sergey Egranov

Dissertations and Theses (Open Access)

Physical activity has been shown to benefit cognitive and mental health by improving cerebrovascular perfusion and regulating hormone-mediated processes on a systemic level. However, the acute effects of physical activity, such as locomotion, on the neuronal circuits underlying cognitive processes have yet to be fully characterized. This body of work seeks to rectify this gap in knowledge through analysis of how both behavioral performance and neuronal activity signatures in visual and executive brain regions are modulated post-locomotion in rhesus macaques.

To this end, we performed high-yield electrophysiological recordings simultaneously from area V4, a mid-tier visual cortical region, and the dorsolateral …

Understanding How Hearing Works, Cecilia Zoutewelle

A. The Science of Sound

A 7-page introductory overview of the anatomical and neurological processes of hearing, with illustrations and bullet-point summaries. 

Robust And Generalizable Representations In The Hippocampus, Hung-Tu Chen

Dartmouth College Ph.D Dissertations

An intelligent system must balance generalizing across similar experiences with maintaining the distinctiveness of each experience. This thesis explores how the hippocampus manages this balance through its neural representations to support adaptive behavior. In Chapter 1, I provide an overview of key hippocampal phenomena that contribute to this process, including remapping, splitter signal, and replay. In Chapter 2, I challenge the concept of random remapping by showing that it is possible to predict, better than chance, how a given experience will be encoded in the hippocampus across different subjects. This suggests that encoding of related experiences, which was previously thought …

Local Geometry Of Elementary Visual Computations, Peter Neri

MODVIS Workshop

Visual operators (e.g. edge detectors) are classically modelled using small circuits involving canonical computations, such as template-matching and gain control. Circuit models explain many aspects of the empirical descriptors that are used to characterize local visual operators, from sensitivity to classification images. Notwithstanding their utility, these models fail to provide a unified framework encompassing the variety of effects observed experimentally, such as the impact of contrast, SNR, and attention on the above descriptors. My goal is to start with a simple, plausible geometrical representation of the perceptual operation carried out by the observer, and to show that this representation is …

Individual Differences In Age And Testosterone Are Uniquely Associated With Neural Oscillatory Activity Serving Verbal Working Memory In Children And Adolescents, Abraham D. Killanin

Theses & Dissertations

During the sensitive period of adolescence, the human brain undergoes dynamic changes in structure and function resulting in vast executive function gains. Verbal working memory (VWM) is one executive function that serves as a foundation to language acquisition, reading, and learning. Many have examined the development of VWM in youth, but few have probed age-related changes in the underlying neural oscillatory dynamics, and none have examined testosterone-related changes. We recorded magnetoencephalography during a modified Sternberg VWM task in 82 youth participants aged 6 – 14 years old and collected salivary testosterone samples. Significant oscillatory responses were identified and imaged using …

The Effect Of Repetitive Transcranial Magnetic Stimulation On Brain And Cognitive Variables In Patients With Amnestic Mild Cognitive Impairment, Connor J. Phipps

Theses & Dissertations

Healthy and pathological aging processes can impact human memory. Current interventions for clinical memory impairment offer little opportunity for restoration of memory ability. Fortunately, a novel therapy in the form of repetitive transcranial magnetic stimulation (rTMS) has exhibited promise in this regard. In healthy adults, rTMS of the angular gyrus (AG) has been reported to improve memory. The current study sought to determine the generalizability of these findings to individuals with clinical memory impairment by administering a clinical trial replicating an rTMS protocol reported to improve hippocampal-dependent memory in healthy individuals to individuals with amnestic mild cognitive impairment (aMCI). Individuals …

Biophysical Model Of Retraction Motor Neurons And Their Modification By Operant Conditioning, Maria Rasheed

Dissertations and Theses (Open Access)

Operant conditioning (OC) is a form of associative learning in which an animal modifies its behavior based on the consequences that follow that behavior. Despite its ubiquity, the underlying mechanisms of OC are poorly understood. Insights into the mechanisms of OC can be obtained by studying Aplysia feeding behavior as it can be modified by OC. This behavior is mediated by a central pattern generator (CPG) network in the buccal ganglia that contains a relatively small number of neurons. This CPG generates rhythmic motor patterns (BMPs) that move food into the gut by closing a tongue-like structure (i.e., radula) during …

Evaluating The Potential Of Using Eeg To Monitor Cognitive Workload In Simulated Suborbital Flight, Erik Seedhouse

Journal of Aviation/Aerospace Education & Research

Mental workload can be assessed using electrophysiological measures of brain activity, such as electroencephalography (EEG). EEG signals reveal cortical electrical activity. This cortical activity was recorded using specialized headsets. The focus of this research was to study cognitive performance (CP) in four pilots during simulated suborbital flights under nominal day and night profiles and under contingency day and night profiles. A 14-channel EMOTIV EEG headset measured the participants' brain activity while they flew simulated flights in a Suborbital Spaceflight Simulator (SSFS). Several sessions of EEG data were recorded from each subject, and feature extraction was applied. Data revealed that real-time …

Active Encoding Of Space Through Time, Michele Rucci, Jonathan D. Victor

MODVIS Workshop

No abstract provided.

Consciousness, Evolution, And The Self-Organizing Brain, Karen Seymour

Journal of Conscious Evolution

While evolution is guided by natural selection, it is internally driven by self-organizing processes. The brain encompasses these complementary forces and dynamics of evolution in both its structure and dynamics by embodying a historical record of the factors that have shaped it throughout its evolutionary past, as well as by being shaped by selective parameters in real time. Self-organization is evident in not only the brain’s structure and form, but also in the processes that support consciousness. From the convergence of complex structure and the novelty-generating dynamics of chaos that both characterize the brain arises the experience of explicit consciousness, …

Reversible Emerging Neuropsychological Pattern In Chronic Intractable Migraine, Tanner Williford, Pooja Chemiti, Mason Allen, Brandon Burrell, Stephanie Chavez, Jude Emego, Bridger Gunter, Matthew Huertas, Matthew Jennings, Roshni Jogin, Paulo Kelly, Laura Minor, Steven Salazar, Jameson Williams, David W. Sant, John A. Kriak, Kyle B. Bills

Annual Research Symposium

No abstract provided.

Aberrant Age-Related Alterations In Spontaneous Cortical Activity In Participants With Cerebral Palsy, Hannah Bergwell

Theses & Dissertations

Cerebral Palsy (CP) is the most common neurodevelopmental motor disability, resulting in life-long sensory, perception and motor impairments. These impairments appear to drastically worsen with advancing age within the CP population, although the underlying neuro-physiological mechanisms remain poorly understood. Herein, we began to address this knowledge gap by utilizing magnetoencephalographic (MEG) to study how aging impacts the amplitude of spontaneous brain activity (i.e., resting state) in a cohort of 38 individuals with spastic diplegic CP (Age = 22.08 ± 10.46 years) and 67 neurotypical controls (NT) (Age = 19.56 ± 10.25 years). Participants completed an eyes-closed resting-state paradigm while undergoing …

Impact Of Brain State On Visual And Prefrontal Population Coding In Behaving Animals, Russell Milton

Dissertations and Theses (Open Access)

Patterns of neural activity in the brain constantly shift between different processing states. Earlier studies have established that the ongoing, spontaneous activity has major repercussions regarding how the brain processes incoming sensory stimuli. However, the interaction between behavioral activity and brain states throughout the cortical hierarchy of primates has not been understood. In particular, technical considerations have greatly limited the range of physical activities in which primate neuronal activity can be recorded. We have implemented two separate strategies to overcome these limitations. First, we have advanced wireless electrophysiological methodologies that enable recording high-yield neuronal data from animals as they freely …

The Neurological Asymmetry Of Self-Face Recognition, Aleksandra Janowska, Brianna Balugas, Matthew Pardillo, Victoria Mistretta, Katherine Chavarria, Janet Brenya, Taylor Shelansky, Vanessa Martinez, Kitty Pagano, Nathira Ahmad, Samantha Zorns, Abigail Straus, Sarah Sierra, Julian Keenan

Department of Biology Faculty Scholarship and Creative Works

While the desire to uncover the neural correlates of consciousness has taken numerous directions, self-face recognition has been a constant in attempts to isolate aspects of self-awareness. The neuroimaging revolution of the 1990s brought about systematic attempts to isolate the underlying neural basis of self-face recognition. These studies, including some of the first fMRI (functional magnetic resonance imaging) examinations, revealed a right-hemisphere bias for self-face recognition in a diverse set of regions including the insula, the dorsal frontal lobe, the temporal parietal junction, and the medial temporal cortex. In this systematic review, we provide confirmation of these data (which are …

Cortical Dynamics Of Language, Kiefer Forseth

Dissertations and Theses (Open Access)

The human capability for fluent speech profoundly directs inter-personal communication and, by extension, self-expression. Language is lost in millions of people each year due to trauma, stroke, neurodegeneration, and neoplasms with devastating impact to social interaction and quality of life. The following investigations were designed to elucidate the neurobiological foundation of speech production, building towards a universal cognitive model of language in the brain. Understanding the dynamical mechanisms supporting cortical network behavior will significantly advance the understanding of how both focal and disconnection injuries yield neurological deficits, informing the development of therapeutic approaches.

Corticospinal Excitability During A Perspective Taking Task As Measured By Tms-Induced Motor Evoked Potentials, Elizabeth Murray, Janet Brenya, Katherine Chavarria, Karen J. Kelly, Anjel Fierst, Nathira Ahmad, Caroline Anton, Layla Shaffer, Kairavi Kapila, Logan Driever, Kayla Weaver, Caroline Dial, Maya Crawford, Iso Hartman, Tommy Infantino, Fiona Butler, Abigail Straus, Shakeera L. Walker, Brianna Balugas, Matthew Pardillo, Briana Goncalves, Julian Keenan

Department of Biology Faculty Scholarship and Creative Works

Only by understanding the ability to take a third-person perspective can we begin to elucidate the neural processes responsible for one’s inimitable conscious experience. The current study examined differences in hemispheric laterality during a first-person perspective (1PP) and third-person perspective (3PP) taking task, using transcranial magnetic stimulation (TMS). Participants were asked to take either the 1PP or 3PP when identifying the number of spheres in a virtual scene. During this task, single-pulse TMS was delivered to the motor cortex of both the left and right hemispheres of 10 healthy volunteers. Measures of TMS-induced motor-evoked potentials (MEPs) of the contralateral abductor …

Rehabilitative Movement Approaches And Dance Interventions In Parkinson’S Disease, Cecilia Fontanesi

Dissertations, Theses, and Capstone Projects

The scope of this work is to address the functional deficits and symptoms experienced by those living with Parkinson’s Disease through movement interventions.

Chapter 1 offers a brief overview of current pharmacotherapy and rehabilitation approaches in Parkinson’s, focusing on dance in particular as a movement intervention that may be particularly suited to this population.

Chapter 2 focuses on brain plasticity and motor learning in PD, reporting the effects of rTMS applied after the acquisition of a motor skill. In this study, adaptation tested in patients with PD was comparable in the sham and TMS sessions, while retention indices tested on …

Preliminary Evidence Of The Role Of Medial Prefrontal Cortex In Self-Enhancement: A Transcranial Magnetic Stimulation Study, Birgitta Taylor-Lillquist, Vivek Kanpa, Maya Crawford, Mehdi El Filali, Julia Oakes, Alex Jonasz, Amanda Disney, Julian Keenan

Department of Biology Faculty Scholarship and Creative Works

Humans employ a number of strategies to improve their position in their given social hierarchy. Overclaiming involves presenting oneself as having more knowledge than one actually possesses, and it is typically invoked to increase one’s social standing. If increased expectations to possess knowledge is a perceived social pressure, such expectations should increase bouts of overclaiming. As the medial prefrontal cortex (MPFC) is sensitive to social pressure and disruption of the MPFC leads to decreases in overclaiming, we predicted that transcranial magnetic stimulation (TMS) applied to the MPFC would reduce overclaiming and the effects would be enhanced in the presence of …

The Current Neuroscientific Understanding Of Alzheimer's Disease, Rachel A. Brandes

Pursuit - The Journal of Undergraduate Research at The University of Tennessee

Alzheimer’s disease is a degenerative neurological illness characterized by the deterioration of brain regions implicated in memory and cognitive function. While researchers have yet to find a cure or effective treatment, they have gained a better understanding of its pathology and development. Through years of neuroscience research, scientists have discovered much of what happens in the brain during Alzheimer’s disease onset and how this causes its symptoms; many hypotheses regarding this aspect of the illness involve temporal lobe atrophy, neurofibrillary tangles, and amyloid plaques. Although Alzheimer’s disease affects millions of people every day, it seems that most are unaware of …

Mechanisms Of Value-Biased Prioritization In Fast Sensorimotor Decision Making, Kivilcim Afacan-Seref

Dissertations and Theses

In dynamic environments, split-second sensorimotor decisions must be prioritized according to potential payoffs to maximize overall rewards. The impact of relative value on deliberative perceptual judgments has been examined extensively, but relatively little is known about value-biasing mechanisms in the common situation where physical evidence is strong but the time to act is severely limited. This research examines the behavioral and electrophysiological indices of how value biases split-second perceptual decisions and the possible mechanisms underlying the process. In prominent decision models, a noisy but statistically stationary representation of sensory evidence is integrated over time to an action-triggering bound, and value-biases …

Sensory Perception, Adrian Rodriguez-Contreras

Open Educational Resources

Different types of sensory systems with their functional modalities will be presented. The biological bases for how these functions are generated and modified will then be described. As vision is the principal means of perception, we will focus in this course most on visual processing. Scientific data will be integrated into the lectures, such that students develop critical skills in analyzing data and proposing hypotheses.

Feedforward And Feedback Signals In The Olfactory System, Srimoy Chakraborty

Graduate Theses and Dissertations

The conglomeration of myriad activities in neural systems often results in prominent oscillations. The primary goal of the research presented in this thesis was to study effects of sensory stimulus on the olfactory system of rats, focusing on the olfactory bulb (OB) and the anterior piriform cortex (aPC). Extracellular electrophysiological measurements revealed distinct frequency bands of oscillations in OB and aPC. However, how these oscillatory fluctuations help the animal to process sensory input is not clearly understood. Here we show high frequency oscillations in olfactory bulb carry feedforward signals to anterior piriform cortex whereas feedback from the aPC is predominantly …

Interhemispheric Communication And Lateralization In The Mouse Hippocampus, Jake Jordan

Dissertations, Theses, and Capstone Projects

The hippocampus is essential for memory and spatial navigation. Many theories have been proposed to explain how the hippocampus contributes to cognition; however, none has fully explained relevant neurophysiological and behavioral data. Hemispheric lateralization of hippocampal function has been reported in humans and in rodents, and lateralization of hippocampal neural circuitry has been reported in rodents. Most theories of hippocampal function fail to consider the hippocampus as a bilateral structure with hemispheric differences. Further, proposed theories of hippocampal lateralization have their own limitations in explaining empirical data concerning left/right function. Little is known about communication between the hippocampi across hemispheres. …