PROJECT SUMMARY / ABSTRACT Circuits in the healthy central nervous system (CNS) have the capacity for reorganization and remapping of functionality. Growing evidence suggests that circuit remapping may contribute to a number of neurologic diseases as well. For example, it has been widely hypothesized that remapping of circuits underlies recovery after a focal lesion of the CNS, such as stroke. However, how specific changes in neuronal circuits mediate improvement in function and recovery after cortical injury remains a major gap in our understanding. Here, Dr. Zeiger will utilize advanced techniques for imaging and manipulating circuits in vivo to define the local and global changes in neural circuits that occur following a lesion of the somatosensory cortex in mice. In Aim 1, Dr. Zeiger will investigate the role of GABAergic parvalbumin (PV) cells in peri-lesional remapping of somatosensory function after small lesions to the cortex. PV cells shape cortical sensory representations and regulate experience-dependent plasticity. Dr. Zeiger hypothesizes that PV cells in peri-lesional cortex play a critical role in functional remapping. He will test this hypothesis by 1) recording sensory-evoked responses from PV and pyramidal cells throughout recovery using in vivo two-photon (2P) calcium imaging and 2) modulating PV cell activity using DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) and measuring the effects on circuit remapping. In Aim 2, Dr. Zeiger will identify novel candidate brain regions for remapping of lost functionalities that mediate behavioral recovery after large cortical lesions. He hypothesizes that remapping after large lesions involves distributed networks of neurons across multiple brain regions. He will test this by generating a quantitative atlas of all remapped whisker-responsive neurons following recovery, allowing identification of novel candidate regions important for remapping. He will then measure changes in circuit function in these sites over time during recovery and confirm the roles of these regions by manipulating neuronal activity with DREADDs and testing the effect on recovery of somatosensory function. Dr. Zeiger is currently an Assistant Professor in Neurology at the University of California – Los Angeles (UCLA). His long-term career goal is to work as a physician-scientist investigating mechanisms of circuit dysfunction contributing to neurologic disease. As part of this proposal he will carry out a detailed career development plan focusing on gaining technical skills in advanced neuroscience methods for investigating neuronal circuits, expanding his knowledge of how circuit dysfunction contributes to movement disorders, and transitioning to an independent career. This work will be carried out at UCLA, a renowned research institution with an extensive community of investigators in neuroscience and neurology and supported by numerous institutional resources such as the UCLA Clinical and Transla...