<b>Cortical circuits underlying contextual control of sensory space</b>

<p dir="ltr">Successful interaction with our surroundings involves both bilateral sensorimotor integration and the ability to prioritize stimuli based on their behavioral relevance. In this dissertation, I address these two interrelated yet distinct dimensions of sensorimotor processing: 1) the cortical mechanisms underlying bilateral integration, and 2) the emergence of value-based coding in the brain.</p><p dir="ltr">To investigate how the brain integrates bilateral tactile information, we recorded neural activity simultaneously from the left and right primary somatosensory cortices (S1) in mice trained to coordinate tactile features across hemispheres. Reward-associated stimuli evoked more bilaterally symmetric whisking, bilateral facilitation, and enhanced interhemispheric synchrony. These effects were absent in naïve mice and were abolished by silencing callosal projections. We next recorded bilaterally from the motor cortex (MC) to unravel its role in bilateral integration. In mice trained on a bilateral discrimination task, MC neurons developed task-specific, movement-independent bilateral representations, accompanied by strengthened interhemispheric coupling. This pattern was not observed in mice trained on a unilateral discrimination task. Silencing the S1→MC pathway impaired behavioral performance and disrupted bilateral stimulus representations in MC. These findings indicate that cortical circuits supporting bilateral integration are modulated by behavioral context and rely on information flow from S1.</p><p dir="ltr">To examine how spatial maps become value-based, we recorded from S1 and the superior colliculus (SC) during a task requiring mice to distinguish between stimuli of opposing value. While S1 maintained a balanced somatotopic representation, SC exhibited a pronounced bias toward the rewarded stimulus, driven by suppression of responses to the negative stimulus and depended on the opportunity for choice. Together, these findings identify distinct neural substrates for bilateral integration and value coding in the sensorimotor system.</p>