The Hollis lab studies the reorganization of neural circuits during learning and rehabilitation from injury. Our principal research focus is on the function of cortical motor networks after spinal cord injury. Our studies lie at the intersection of molecular biology and systems neuroscience, with an eye towards translation. We utilize optogenetic stimulation of, and optical recording from, cortical motor networks in order to understand the mechanisms that enable neural circuit remodeling after injury.

Dr. Hollis’ previous work demonstrated the role of circuit remodeling in promoting functional recovery of sensory and motor circuits after spinal cord injury. He demonstrated that cortical motor representations shift in response to rehabilitation and induced remodeling of the corticospinal circuit after injury. Our current work utilizes chemogenetic and optogenetic tools to investigate cortical plasticity and the integration of altered corticospinal circuits into a functional motor network.

Motor cortex plasticity after spinal cord injury. Optical mapping of Thy1-channelrhodopsin mice, shows evoked motor maps (top insets). C5 spinal cord injury results in interruption of corticospinal axons (bottom insets). Early adaptation of maps after descending axon interruption shows increased forelimb flexor map (red) with concomitant reduction of motor responses caudal to C5. Rehabilitation coincident with corticospinal regenerative sprouting promotes motor map reorganization: expansion of proximal extensor maps into denervated hindlimb regions. Illustration courtesy of Sydney Agger (2016).