BME PhD Preliminary Exam Announcement for Hayagreev Vadhiraj Sarma Keri (S. Pluta and K. Jayant, co-advisors)

Everyone is invited to attend the public presentation beginning at 2:00 PM.

TITLE: Cortical circuit mechanisms underlying the goal-directed flow of bilateral cues

EXAM DATE: 12/12/2023

TIME: 2:00 PM

LOCATION: MJIS 2001

COMMITTEE MEMBERS:

Dr. Scott Pluta (Primary advisor)

Dr. Krishna Jayant (Co-advisor)

Dr. Maria Dadarlat

Dr. Edward Bartlett

ABSTRACT:

Animal behavior displays inherent bilateral coordination between the left and right sides of the body. However, the neural mechanisms governing the integration of information across hemispheres to generate a unified perceptual experience remains poorly understood. In this proposal, we address this question by recording activity from the cerebral cortices during goal-directed behavior. Due to lack of ipsilateral touch responses in the primary somatosensory cortex(S1), naïve models assume bilateral integration to happen primarily in higher cortical areas. However, since tactile behaviors necessitate high temporal resolution, we propose that S1, fortified by robust callosal projections from the contralateral hemisphere, likely plays a crucial role in bilateral integration and in tuning stimulus information in downstream regions. To tackle this question, we developed a novel Go/No-go bilateral discrimination task where mice discriminate between bilateral stimuli categories, compelling them to share tactile information across hemispheres. We observed that mice enhance the bilateral whisker movement symmetry during 'Go' stimulus presentation. Examination of neural activity revealed strong temporal coupling between the S1s along with enhanced ipsilateral facilitation modulated by behavioral context. Our findings challenge existing models and propose a novel framework suggesting that behavioral context governs bilateral integration in the sensory cortex. Additionally, neurons in the whisker motor cortex (wMC) were also found to accurately decode sensory and motor variables during the bilateral task. By innovative optogenetic axon silencing of specific feedforward projection neurons, we aim to dissect the circuits underlying this brain-wide computation. Completing this proposal will provide insights on the circuits and cell-types underlying bilateral sensation and movement.