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

Everyone is invited to attend the public presentation beginning at 1:00pm.

TITLE: Cortical circuits underlying contextual control of sensory space

DATE: June 26^th, 2025.                 

TIME: 1:00pm   

LOCATION: LILY 1117

and

Zoom: https://purdue-edu.zoom.us/j/7657149083

COMMITTEE MEMBERS:

Dr. Scott Pluta (Primary advisor)

Dr. Krishna Jayant (Co-advisor)

Dr. Maria Dadarlat

Dr. Edward Bartlett

ABSTRACT:

Coordinated bilateral movements guided by somatosensory feedback are fundamental to animal behavior. This sensorimotor process underlies our ability to integrate stimuli across the hemispheres and create a unified experience.  However, the neural computations and circuits that transform bilateral stimulus information into coordinated actions remain unclear. To address this question, we recorded neural activity bilaterally from somatosensory (S1) and motor (MC) cortices while mice performed a task requiring them to share information between the hemispheres to discriminate between two categories of bilateral stimuli. When expert mice touched stimuli associated with reward, synchronous spiking emerged between the neurons in left and the right S1. The addition of ipsilateral touch primarily facilitated the contralateral whisker response in S1 neurons. This coordinated activity and facilitation were absent in stimulus-matched naïve animals. Silencing of callosal S1 signaling reduced bilateral facilitation and interhemispheric synchrony, indicating that interhemispheric (IH) binding was callosally mediated and is controlled by behavioral context.

In MC neurons, task-specific bilateral representations emerged in mice performing bilateral discrimination. By contrast, MC neurons did not integrate sensory features across hemispheres in mice trained on a task requiring them to discriminate between whisker touches on the same side of the face. Additionally, interhemispheric coupling in MC was stronger during bilateral discrimination than during a unilateral task, where processing was dominated by the hemisphere contralateral to the trained whiskers. Finally, silencing S1-to-MC projections impaired behavioral performance and disrupted MC activity, indicating that S1 input is essential for MC to encode task-relevant bilateral features. Together, these results reveal a state-dependent logic for bilateral integration and interhemispheric coupling in S1 and MC, shaped by behavioral relevance and supported by direct cortical pathways.