Cortical population dynamics after stroke in reaching rats.

This project — the subject of my doctoral dissertation — asked how the role of cortex as a controller of movement evolves during the first weeks after a focal motor-cortex injury. Bilateral microwire arrays were chronically embedded in layer 5 of rat motor areas (rostral and caudal forelimb areas) to record extracellular field potentials and multi-unit spiking while rats performed skilled pellet retrievals, daily, over the first four weeks following a focal vasoconstrictive ischemia targeted to the caudal forelimb area contralateral to the preferred reaching forelimb.

What we found

• Injury changed movement-related spiking in distinct ways across areas and reach phases — for example, a small but significant decrease in rostral forelimb area spike counts just before the advance phase in ischemic animals, alongside changes in retract-phase activity and duration.
• When bilateral population activity was fit with linearized dynamics, the structure of the fit mattered: accurate regression with rotatory (jPCA-style) structure was predictive of a recovery phenotype, while dynamics that only an unconstrained regression could describe predicted poorer pellet-retrieval outcomes — consistent with post-stroke shifts in bilateral network dynamics and inappropriate reintegration of sensory information.
• These results frame impairment at the level of the cortical controller: whether poor outcomes arise from corrupted sensory feedback or from an inability to predict future limb state is the critical next question for rehabilitation.

Full project site: RC-Data → — the complete abstract, methods, and results.

Dissertation: Neurophysiological mechanisms of sensorimotor recovery from stroke (University of Kansas Medical Center, 2020).