Neuroscience and Neurobiology Commons^™

Daily Rhythms In Psychosocial Stress, Sleep, And Mood: A Multimethod Approach To Transdiagnostic Psychopathology Risk And Intervention, Gabriel Gilmore

Theses and Dissertations--Psychology

Rhythms are central to nearly every core physiological and psychological process and have profound influences on overall health and well-being, particularly in the context of mood disorders. This dissertation emphasizes a rhythm-centered framework for understanding transdiagnostic psychopathology, proposing that the temporal organization of psychosocial stress, sleep, and mood provides crucial information for the development and treatment of mood disorder symptomology. Current literature relies primarily on mean symptom levels, overlooking day-to-day patterns in psychosocial experiences. To address this key methodological gap, three studies are examined. Study 1 develops and validates the Psychosocial Stress Regularity Measure (PSRM), a brief single-item measure of …

Building A Cell Specific System For In Vivo Rna Imaging Of The Endogenous Actin Gene In C. Elegans, Jasmine A. Huerta Canete

Theses and Dissertations

Messenger RNA (mRNA) plays a crucial role in protein synthesis and cellular processes, important for the development of cells such as neurons. When dysregulation occurs, it can lead to outcomes such as aberrant translation, causing neurodegenerative conditions to arise. Unfortunately, the localization of mRNA in an in vivo cell specific manner is still not understood. To address this, we decided to develop a cell-specific system to image RNA in vivo, within the organism known as C. elegans with a focus on the actin gene. The Actin gene encodes for an important cytoskeleton protein expressed ubiquitously, vital for the cell …

Orexin Receptor Modulation In Amygdalar Stress Circuitry Differentiates Resilient And Vulnerable Phenotypes, Megan Marie John

Dissertations and Theses

Social stress is important for evaluating threats and resource opportunities, however, chronic exposure initiates the onset of psychological disorders, such as anxiety, depression, and post-traumatic stress disorder (PTSD). Stress responsiveness varies between individuals and sexes, resulting in disproportionate diagnoses and ineffective treatment outcomes. Enhancing therapeutic efficacy requires understanding of stress responsivity, phenotype development, and neurocircuitry modifications. Key contributors to stress responsiveness, such as threat of aggression and motivational initiation, influence the development of resilient or vulnerable phenotypes through behavioral and molecular adaptations to stress-related neurocircuitry. The basolateral amygdala (BLA) is a brain region associated with fear learning and integrates stress …

Varied Environmental Enrichment Schedules Differentially Affect Behavioral Performance, Davis Aschemann

Research Honors

Cognitive decline is a widespread phenomenon affecting a significant proportion of older adults. The mechanisms that cause cognitive decline are still being investigated, with recent evidence indicating that senescent cells are a primary cause of neuroinflammation and neurodegeneration. Environmental enrichment has been linked with the potential curbing and reversal of cognitive decline, specifically the restoration of immune cell function and improved neuroplasticity. Despite the amount of research showing the beneficial effects of environmental enrichment for cognitive decline, paradigms for environmental enrichment are heterogeneous across the literature. A primary factor that differs across studies is the duration of administration of environmental …

The Effects Of Hyperthyroidism On Mouse Corneal Innervation: Implications For Human Cornea Re-Innervation, Anjali Malali

Research Honors

To test the effects of elevated TH during cornea development, our lab has collaborated with Dr. Juan Davila (University of Illinois Urbana-Champaign) to develop an embryonic mouse model of hyperthyroidism. Embryos were exposed to high levels of TH in utero by adding TH to the pregnant mother’s drinking water. Upon collection of the embryos, elevated blood thyroid levels in the pregnant mother were analyzed with an enzyme-linked immunosorbent assay (ELISA), and eye tissues were collected and preserved for analysis of corneal nerve innervation patterns. By utilizing immunohistochemistry in order to visualize corneal innervation in mouse embryos, this project studied whether …

Nonlinear Differences In Postural Sway Across Attentional Focus Conditions In Individuals With And Without Anterior Cruciate Ligament Reconstruction, Natalie L. Ferguson, Brian L. Cone, Christopher K. Rhea, Anne Beethe, Breanna Studenka

Rehabilitation Sciences Faculty Publications

BACKGROUND: The structure of variability in postural sway reflects the adaptability and health of the postural control system. Entropy quantifies this structure by measuring the regularity of repeated fluctuations over time. Although entropy has been used to examine sway in neurological populations, little is known about how sway complexity changes following anterior cruciate ligament reconstruction (ACLR). Attentional focus may also influence postural control, with external focus typically promoting more efficient and automatic regulation than internal focus.

AIM: To examine how attentional focus (internal vs. external) influences the structure of postural sway in individuals with and without ACLR.

METHODS: Forty-three participants …

Eeg Signatures Of Motor Development In Early Childhood: A Systematic Review, Sonia Khurana, Ashwini Kulkarni, Thomas C. Bulea, Hunter J. Bennett

Rehabilitation Sciences Faculty Publications

Background

Early identification of motor developmental disorders is limited due to lack of objective neural markers that characterize typical neurodevelopmental patterns. This systematic review interprets and synthesizes existing evidence to propose a framework of EEG signatures associated with motor development in children aged 0-5 years, which may help inform future benchmarks for early assessment and intervention.

Methods

Following PRISMA guidelines, we searched published and gray literature across five databases between 2000 and 2025 (registered protocol). Included studies examined EEG during task-based, resting-state, or sleep studies linked to motor milestones, task performance, or standardized motor assessments. Study quality was assessed using …

A Cross-Species Meta-Analysis Of Environmental Enrichment Effects On Cognition, Greg S. Fitzgerald

Electronic Theses & Dissertations (2024 - present)

Environmental enrichment --providing animals or people with stimulating, complex surroundings --consistently improves cognitive performance in laboratory rodents. But when similar interventions are tested in humans, the benefits are much smaller. Understanding why matters: if researchers overestimate how well rodent findings will translate, it can mislead expectations for human cognitive interventions.

This dissertation presents the first cross-species meta-analysis comparing environmental enrichment effects on cognition between rodent and human studies. Drawing on 121 studies (71 rodent, 50 human) contributing 478 effect sizes, the analysis used multilevel models with variance correction to account for the statistical dependence created when studies report multiple outcomes. …

Forcing A Molecule To Switch: Quantifying Mechanical Control At The Atomic Scale, A. M. Shashika D. Wijerathna, Markus Zirnheld, Michael L. Hildebrand, Myles Perry, Marjorie Cenese, Yuan Zhang

Physics Faculty Publications

Mechanically induced conformational switching at the single-molecule level represents a fundamental mechanism for molecular functionality, yet quantitative characterization of the underlying force and energy landscape remains limited. Here, we study individual TBrPP-Co(II) molecules on Au(111) using qPlus atomic force microscopy. By reconstructing interaction potentials from 3D Δf(x,y,z) data, we determine a threshold force of ∼96 ± 8 pN and a tip-induced switching interaction energy of ∼38 ± 4 meV associate with the conformational transition. The isolated tip-molecule force follows a power law (exponent ∼6), indicating dominance of long-range van der Waals interactions. …

Exploring The Effects Of Voluntary Wheel Running On Inhibitory Control, Ava Prieto

Honors Theses and Capstones

Inhibitory control, a central component of executive function, is the ability to suppress unwanted actions in response to a stimulus (Verbruggen et al., 2014; Verbruggen et al., 2019) and is one of the best indicators of executive task management as well as the ability to prevent unwanted prepotent responses. This capacity is essential for goal specific behavior and for responding flexibly to challenges. The present study examined the effects of voluntary wheel running on inhibitory control in two cohorts of Long-Evans rats using a rodent variant of the canonical stop-signal task. We found that rats with access to an active …

A Generalized Framework For The “Core” Thalamocortical Circuit Computation, Charles Liu

Dartmouth College Ph.D Dissertations

This thesis explores a biologically inspired computational framework based on a common excitatory-inhibitory circuit in the superficial layers of the cortex. By varying the strength of local feedback inhibition, this single circuit gives rise to distinct unsupervised learning behaviors: strong inhibition leads to clustering and hierarchical clustering, while weak inhibition produces principal component-like representations. From this principle, we develop three algorithms: Lateral Inhibition Clustering (LI-C), Lateral Inhibition Hierarchical Clustering (LI-HC), and Antipodal Iterative Mean Estimation (AIME).

LI-C performs clustering without requiring a predefined number of clusters, using a competitive learning rule to extract dominant patterns from data. LI-HC extends this …

The Serotonin 1b Receptor In Psilocybin’S Therapeutic-Like Mechanisms: From Behavior To Network Reorganization, Sixtine Fleury

Dartmouth College Ph.D Dissertations

Mood disorders represent a substantial and growing global health crisis, with ~10 million adults in the US meeting criteria for a major depressive disorder (MDD). Current first-line treatments such as SSRIs require long-term daily administration and fail a significant proportion of patients, driving renewed interest in rapid-acting alternatives. Psilocybin, a serotonergic psychedelic, shows growing clinical evidence of efficacy in treating depressive and anxiety disorders, often producing therapeutic effects persisting weeks to months following a single dose. Yet, the neural mechanisms underlying these enduring effects remain poorly understood and have been largely attributed to the serotonin 2A receptor (5-HT2AR) based on …

From Meaning To Memory: Assessing The Capacity And Representational Structure Of Visual Working Memory With Meaningful Stimuli, Yong Hoon Chung

Dartmouth College Ph.D Dissertations

Visual working memory is thought to be strictly limited. Yet we remember meaningful, real-world objects better than abstract stimuli. Here I show that this advantage arises from the semantic structure of meaningful objects, not their perceptual features alone, and that it extends even to memory for associated features such as color. In the brain, meaningful objects elicit greater and more distributed delay activity, consistent with the recruitment of higher-level neural processes during maintenance. I propose that semantic knowledge adds representational dimensions that make items more distinctive, and that these dimensions are organized hierarchically with lower-level visual features. These findings recast …

The Role Of The Amygdala In Huntington Disease-Associated Aggression, Luis Torres

Honors Undergraduate Theses

Huntington disease (HD) is a fatal neurodegenerative disorder caused by a trinucleotide CAG expansion in the huntingtin gene (HTT). HD is characterized by motor, cognitive, and psychiatric symptoms that significantly impact patient and caregiver quality of life. Psychiatric symptoms, including depression, anxiety, and irritability, are common manifestations of HD and can emerge years before the onset is clinically diagnosed. Aggression is a common and challenging psychiatric symptom in HD, often misunderstood and associated with caregiver stress, early institutionalization, and reduced quality of life. Despite its clinical impact, aggression in HD lacks effective, targeted treatment options. Similar to HD …

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 …

The Influence Of Limb Dominance On Neural Activation Patterns While Performing Different Motor Control Tasks, Kevin A. Hooks

Graduate Studies Theses and Dissertations 2026

Humans interact with our environment in many ways. One of the most outward-facing aspects of this is limb dominance. The neural underpinnings of limb dominance remain in question today. The objective of this research was to use different methods to analyze neural activation while subjects performed upper extremity motor tasks while recording electroencephalography (EEG). The first experiment used decoding methods to examine whether neural signals collected from the contralateral limb could be used to train a classifier to test on the ipsilateral limb during a reach-to-grasp or reach-to-touch task. It was determined above chance level that within-subject action and direction …

Advances In Active And Passive Integrated Photonic Devices On Thin-Film Lithium Niobate, Pooja S. Kulkarni

Graduate Studies Theses and Dissertations 2026

Thin-film lithium niobate (TFLN) has emerged as a powerful platform for integrated photonics, combining the exceptional electro-optic, nonlinear, and optical properties of bulk lithium niobate with the scalability and compactness of planar nanophotonic technologies. Building on these principles, advanced device architectures such as adiabatic dichroic filters have demonstrated exceptional spectral performance spanning over two octaves of bandwidth on the TFLN platform. Beyond reciprocal devices, it also offers promising pathways toward integrated nonreciprocal components. By leveraging broadband filtering structures and advanced nonlinear photonic design strategies, compact and monolithic optical isolators can be envisioned without relying on traditional magneto-optic materials. In the …

Cell Type-Specific Fatty Acid Signalling And Its Sex Dependence, Emeline Masterson

Graduate Studies Theses and Dissertations 2026

Dietary fat is a highly palatable, energy-dense nutrient whose oral detection powerfully shapes ingestion patterns and metabolic outcomes. Despite clear behavioral and physiological evidence that fat can evoke distinct taste signals, the cellular and molecular mechanisms underlying its transduction remain poorly understood. A critical gap exists in our understanding of the cell-type-specific molecular pathways and how these signals are modulated by hormonal status. This dissertation delineates estrogen-dependent plasticity in FA transduction within the peripheral taste system, revealing coordinated, sex and cell-type-specific modulation of these pathways. To understand the missing mechanisms, FA-evoked responses were compared in Type II cells from wild-type …

Eeg Correlates Of Tactile Synchrony, Devon K. R. Gallagher

Theses and Dissertations (Comprehensive)

New research on the tactile system has suggested that cortical representations of body parts are not fixed, as previously thought, and are instead dynamically maintained through constant sensorimotor information and feedback. Within the somatosensory cortex (S1), the capacity for both permanent and temporary changes have been the topic of ongoing research. The current study aimed to corroborate whether 24 hours of a finger adhesion manipulation is sufficient to elicit behavioural and electrophysiological correlates from cortical reorganization of digit representations in S1, using a behavioural paradigm outlined by Kolasinski et al. (2016). Through electroencephalography (EEG) recording during a tactile discrimination task, …

Preserved Artificial Grammar Learning In Individuals With Parkinson’S Disease: A Systematic Review, Sarah I. Cranna

Honors Theses and Capstones

Abstract

            Implicit statistical learning is a crucial cognitive function that is highly involved in the learning and processing of language. Since both language and implicit statistical learning are supported by the basal ganglia through cortico-striatal networks, disruptions to this network could result in their impairment. Parkinson’s Disease (PD) can therefore be used to model disruptions to this system as it is primarily characterized by dysfunction in the basal ganglia. Thus, this review aims to examine the current literature studying the performance of individuals with PD on artificial grammar tasks in order to investigate the impact of impaired basal ganglia function …