Semester

Fall

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Biology

Committee Chair

Gary Marsat

Committee Member

Kevin Daly

Committee Member

Eric Horstick

Abstract

Sensory systems in animals have evolved to translate physical stimuli into neural representations that, in turn, guide behavior. Feedback is critical in these processes, allowing organisms to filter redundant information and respond effectively to relevant stimuli. In humans, for example, the cerebellar flocculus provides feedback to the vestibulo-ocular reflex to stabilize eye movements during body rotation. In bats, the feedback during echolocation helps prioritize essential signals from the environment. In weakly electric fish, cerebellar feedback helps filter out redundant low-frequency modulations caused by conspecifics, enabling them to detect prey and other relevant signals. However, the influence of cerebellar feedback on high-frequency sensory signals in more realistic, behaviorally relevant contexts still needs to be better understood. This research aims to fill this gap by investigating the role of feedback in processing high-frequency, spatially localized envelope modulations in the electrosensory system of weakly electric fish. By examining the effects of cerebellar feedback on the encoding of conspecific signals, we aim to deepen our understanding of how feedback mechanisms influence sensory processing across different sensory modalities. We found that although not on a per-cycle basis, feedback does cancel high-frequency envelope signals as well as low frequencies. This feedback is driven by a previous cycle of the envelope- but we wanted to narrow down further how many cycles previous to the one of interest it took to drive the feedback. We found that for low frequencies, it takes one stimulus cycle to drive the feedback, whereas higher frequencies took longer and more cycles for the feedback to be active. Finally, we determined how feedback changes for spatial discrimination. Specifically, if the entire duration of the stimulus had a higher discrimination error or if only the first 200 milliseconds was higher. We found that the discrimination errors between feedback intact versus blocked were significantly different for the entire duration of the stimulus, whereas the discrimination errors were similar for the first 200 milliseconds of the stimulus.

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