Abstract WP151: Targeted Engagement of the Premotor Component of the Motor Network After Stroke

Abstract

Introduction: Dorsal premotor cortex (PMd) is an important neural correlate of motor recovery after stroke. A protocol that targets engagement of this component of the motor network through changes in task demands may be a useful rehabilitation tool. Therefore, the purpose of this study was to determine the response to a period of practice targeted at PMd using a well-defined behavioral condition (action selection). Methods: Twelve individuals post-stroke (age: 56.9±7.7 years; months post-stroke: 46.5±46.7; UE FM motor score: 41.8±14.9) completed a task that required right or left movement of a joystick with the weaker hand under two conditions. In the Select Condition, the individual moved right or left based on an abstract, visual rule; this condition has been shown to activate PMd. In the Execute Condition, the individual moved the same direction on every trial. The task was practiced for four consecutive days and completed during functional MRI on Days 1 and 4. Results: Accuracy improved and reaction time (RT) cost (Select RT-Execute RT; represents the relative increase in planning time for the Select condition) decreased over practice ( p =0.005). On Day 1, Select Condition performance led to increased activation compared to Execute performance in bilateral PMd, bilateral parietal, and contralesional prefrontal cortices as expected. On Day 4, the increase in activation during the Select condition was overall less with a significant interaction in three contralesional brain regions: PMd, dorsolateral prefrontal, and anterior cingulate. Individuals with greater activation in the task relevant network (ipsilesional PMd and cingulate cortices, bilateral parietal cortices) on Day 1 had better performance (lower RT cost) on Day 4. Behavioral performance on Day 1 did not predict performance on Day 4 ( p =0.941). Conclusions: Behavioral practice targeted at the premotor component of the motor network can change the activation pattern in task-related regions. Additionally, the degree to which the task-related network is recruited initially may predict who responds best to behavioral practice targeted at that network. These finding may have implications for the structure of motor practice during rehabilitation after stroke.