A Mouse Model for Studying Stroke Induced Impairments, Recovery, and Compensation in the Motor Cortex

Background and Purpose Skilled reaching movements are an important aspect of human motor behavior, but are impaired following motor system stroke. The purpose of this study was to document skilled movements in mice before and after a focal motor cortex stroke for the purpose of developing a mouse model of human stroke. Methods Male C57/BL6 mice were trained to reach with a forelimb for food pellets and then given a motor cortex stroke, induced by pial stripping, contralateral to their preferred reaching limb. Reaching success and the movements used in reaching were analyzed by frame-by-frame inspection of presurgical and postsurgical video records. Results Reaching success was severely impaired following the stroke. Improvement in success over two postsurgical weeks was moderate. Analysis of ten movement components, comprising reaches preand postsurgically, indicated that most of the rotatory movements of the limb used for aiming, advancing, pronating, and supinating the paw were impaired. When successful reaches did occur, body movements that compensated for the impairments in limb rotatory movements aided them. Conclusions The results indicate that skilled reaching in the mouse is impaired by focal motor cortex stroke and they suggest that the mouse, and the skilled reaching task, provides an excellent model for studying impairments, compensation, and recovery after motor system stroke.