Optical Imaging Reveals Functional Network Architecture of Sensorimotor Cortex in Monkeys

Skilled movements require the coordination of neural activity throughout sensorimotor cortex. The most direct route of connectivity within and between sensorimotor cortical areas are corticocortical connections, which bind somatotopic regions of premotor cortex (PM), primary motor cortex (M1), and primary somatosensory cortex (S1). Although many such connections have been identified in previous work, the architecture of the functional network that they form is not clear due to limitations in connectivity tracing approaches. Consequently, how neural activity in sensorimotor cortex is coordinated in service of skilled movements is not known. The studies presented in this dissertation aimed to develop, benchmark, and utilize novel connectivity tracing approaches that were capable of identifying organizational features of connectivity in monkey sensorimotor cortex. Toward this objective, we used intrinsic signal optical imaging (ISOI) in stimulus-evoked and resting state paradigms to measure corticocortical connectivity throughout squirrel monkey sensorimotor cortex. ISOI was capable of measuring connectivity in vivo for a large number of cortical sites and at high spatial resolution. We benchmarked our connectivity results against neuroanatomical tracers, the gold standard of connectivity mapping, to show that ISOI accurately measured monosynaptic corticocortical connectivity. Next, we analyzed connectivity throughout sensorimotor cortex using supervised and unsupervised analyses to identify key organizational features of the sensorimotor network. Every point within sensorimotor cortex was preferentially connected to functionally matched zones spanning multiple cortical areas. Connectivity between non-matched functional zones was dependent on cortical area. Connections between motor and sensory areas mostly targeted proprioceptive sensory zones. These organizational features converge to grant insight into how the sensorimotor network contributes to the generation of skilled movements. Collectively, the studies presented here lay the foundation for measuring cortical network architecture at high spatial resolution