Motor somatotopy in the striatum of rat: manipulation, biting and gait.

The objective of this study was to examine the hypothesis of somatotopically organized motor functions in the striatum. In Experiment 1, ibotenate-induced lesions of the rostrolateral striatum in rats produced a transient decrease of ad libitum food intake, a more enduring decrease of body weight, and chronic impairments of food biting, holding of hard food pellets and feeding efficiency, with no apparent alterations of gait balance in a beam walking task. Lesions of the medial striatum had minimal or no reliable effects on any of the measured parameters. In Experiment 2, the motoric effects of ibotenate lesions restricted to either the dorsomedial or the dorsolateral or the ventrolateral regions of the rostral striatum were examined. Lesions of the dorsolateral striatum produced the most deleterious effect on holding postures of the forelimbs, whereas lesions of the ventrolateral striatum maximally affected food biting, feeding efficiency, ad libitum food intake, and body weight. No regional lesions affected gait balance. Dorsomedial striatal lesions did not affect any of the measured parameters. The findings support the hypothesis of a somatotopically organized role of the rostrolateral striatum in orofacial and forelimb motor control.