Abstract

Network-level modelling of neural function incorporates activity in specific brain regions along with a measure of the interactions between these regions (“connectivity”). Connectivity can be assessed through several means, for example through tractography (structural connectivity) or correlated temporal evolution of neural activity (functional connectivity). These analyses have provided valuable insight into several aspects of brain function, such as top-down control, memory, and navigation. This work focuses on studying neural activity within and between several brain regions across different brain states: namely, during motor actions, sensory perception, brain-computer interface engagement, task-free fluctuations in arousal state, and ischemic injury. High gamma (70-170 Hz) coherence increases between sensory-motor cortical regions in response to a button press but does not increase at similar magnitudes across auditory cortex after auditory sensory stimuli. Additionally, this coherence increase is independent of the increase in high gamma activity within individual sensory-motor cortical regions. Similarly, when motor cortical activity is modulated to control a cursor via a brain-computer interface, high gamma activity increases, and is coupled with a modest increase in high gamma coherence across motor cortex, showing that physiologic functional connectivity changes can be recapitulated by BCI engagement. Naturally occurring variations in arousal state are also associated with distinct network profiles. First, two key brain areas involved in arousal circuitry and processing salience of sensory stimuli, the amygdala and basal forebrain, display a uniquely strong and coherent oscillation at ~30-40 Hz during high arousal states, potentially indexing a coordinated arousal modulation of the processing of sensory stimuli. Second, most cortical and subcortical brain areas show relatively increased alpha (8-15 Hz) coherence during low arousal states. However, medial temporal areas involved in declarative memory encoding and retrieval do not strongly increase alpha coherence with other regions during the low arousal state. Exclusion of these regions from a general pattern of increased alpha coherence, may reflect memory related processing during low arousal states. Finally, an experimental pipeline to generate focal ischemic white matter motor lesions and study changes in white matter integrity and resting state functional connectivity through MRI is described.

Committee Chair

Daniel Moran

Committee Members

Eric Leuthardt, Benjamin Philip; David Bundy; Harold Burton; Janine Bijsterbosch

Degree

Doctor of Philosophy (PhD)

Author's Department

Biomedical Engineering

Author's School

McKelvey School of Engineering

Document Type

Dissertation

Date of Award

3-16-2026

Language

English (en)

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