SPATIAL AND TEMPORAL DYNAMICS OF CORTICOSTRIATAL PLASTICITY DURING MOTOR SKILL LEARNING

Motor skill learning relies on the gradual refinement and stabilization of actions through practice. The dorsal striatum plays a central role in these processes, with its medial (DMS) and lateral (DLS) subdivisions contributing differently to learning and performance. While synaptic plasticity at corticostriatal synapses is thought to support motor skill acquisition, how such plasticity is dynamically organized across the dorsal striatum during learning remains unclear. To address this question, we developed a head-fixed behavioral task in mice to probe the acquisition of a new motor skill over extended training. Behavioral performance was analyzed using an unsupervised, data-driven approach based on multiple kinematic and task-related parameters. This analysis revealed that mice successfully learned the task while adopting distinct behavioral strategies. Ongoing longitudinal analyses of behavioral trajectories aim to determine whether some animals progressively automatize their behavior, whereas others maintain more flexible strategies. To track corticostriatal synaptic plasticity, we performed chronic in vivo recordings of optogenetically evoked local field potentials, allowing repeated assessment of cortical input strength in the dorsal striatum. The DLS exhibited robust, rapid, and sustained long-term potentiation of cortical inputs across training, whereas the DMS showed stable responses or a slow, gradual decrease consistent with long-term depression. Importantly, disrupting DLS plasticity using low-frequency stimulation impaired both synaptic potentiation and behavioral performance, suggesting that sustained DLS plasticity contributes to motor skill acquisition. Together, these results highlight a dynamic and spatially organized reconfiguration of corticostriatal synapses during skill learning.