Behavioral and Movement Disorders Induced by Local Inhibitory Dysfunction in Primate Striatum

The current model of basal ganglia organization postulates their functional division into sensorimotor, associative, and limbic territories, implicated, respectively, in motor, cognitive, and motivational aspects of behavior. Based on this model, we previously demonstrated, in the external segment of globus pallidus of monkeys, that the same neuronal dysfunction induced dyskinesia or abnormal behavior depending on the functional territory. To extend these findings, we performed bicuculline microinjections into the different functional territories of the striatum in 6 monkeys. Abnormal movements were observed after microinjections into the posterior putamen, corresponding to the sensorimotor territory, and into the dorsal part of the anterior striatum, corresponding to the associative functional territory. Within the ventral striatum, referred to as the limbic functional territory, we identified 3 subregions corresponding to different types of abnormal behaviors. Simultaneous neuronal recordings performed close to the microinjection sites confirmed that bicuculline produced a focal increase of neuronal activity surrounded by a zone with neuronal hypoactivity. This study provides new evidence for the involvement of specific striatal regions in movement as well as in a large spectrum of behavioral disorders and suggests that local inhibitory dysfunction could be a pathological mechanism of various neurological and psychiatric disorders.