Motor functions of the striatum in the rat: critical role of the lateral region in tongue and forelimb reaching.

The findings of this study indicate a critical and selective role of the rat's lateral striatum in performance of tongue and forelimb reaching. To test the hypothesis of regional specificity of motor control in the striatum, the effects of bilateral, ibotenate-induced lesions of either the lateral or the medial regions of the striatum on reaching movements of the tongue and the forelimbs were examined. Lesions of the lateral striatum caused severe and chronic impairments of movement initiation, postural synergisms and amplitude of both tongue and forelimb reaches. In contrast, lesions of the medial striatum produced mild or no chronic alterations of these motor parameters. These findings support the hypothesis of a selective role of the lateral striatum in the initiation and execution of reaching movements.