UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    STABILITY AND SCALING OF NEURONAL AVALANCHES AND THEIR RELATIONSHIP TO NEURONAL OSCILLATIONS
    (2019) Miller, Stephanie Regina; Roy, Rajarshi; Biophysics (BIPH); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The generation of cortical dynamics in awake mammals is not yet fully understood. However, it is known that neurons leverage distinct organizational schemes to achieve behavior and cognitive function, and that this precise spatiotemporal organization may go awry in illness. In 2003, a form of scale-free synchrony termed “neuronal avalanches” was first observed by Beggs & Plenz in cultured cortical tissue and later confirmed in rodents, nonhuman primates, and humans. In this dissertation, we draw from monkey and rodent studies to demonstrate that neuronal avalanches capture key features of neural population activity and constitute a robust and stable (e.g. self-organized) indicator of balanced excitation and inhibition in cortical networks. We also show for the first time that neuronal avalanches and oscillations co-exist in frontal cortex of nonhuman primates and identify the avalanche temporal shape as a biomarker predicated upon critical systems theory. Finally, we present progress towards characterizing altered avalanche dynamics in a developmental mouse model for schizophrenia using 2-photon calcium imaging in awake animals.
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    PRINCIPLES OF INFORMATION PROCESSING IN NEURONAL AVALANCHES
    (2011) Yang, Hongdian; Roy, Rajarshi; Plenz, Dietmar; Chemical Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    How the brain processes information is poorly understood. It has been suggested that the imbalance of excitation and inhibition (E/I) can significantly affect information processing in the brain. Neuronal avalanches, a type of spontaneous activity recently discovered, have been ubiquitously observed in vitro and in vivo when the cortical network is in the E/I balanced state. In this dissertation, I experimentally demonstrate that several properties regarding information processing in the cortex, i.e. the entropy of spontaneous activity, the information transmission between stimulus and response, the diversity of synchronized states and the discrimination of external stimuli, are optimized when the cortical network is in the E/I balanced state, exhibiting neuronal avalanche dynamics. These experimental studies not only support the hypothesis that the cortex operates in the critical state, but also suggest that criticality is a potential principle of information processing in the cortex. Further, we study the interaction structure in population neuronal dynamics, and discovered a special structure of higher order interactions that are inherent in the neuronal dynamics.