THE TEMPORAL-LOBE IS A TARGET OF OUTPUT FROM THE BASAL GANGLIA

The basal ganglia are known to receive inputs from widespread regions of the cerebral cortex, such as the frontal, parietal, and temporal lo bes. Of these cortical areas, only the frontal lobe is thought to be t he target of basal ganglia output. One of the cortical regions that is a source of input to the basal ganglia is area TE, in inferotemporal cortex. This cortical area is thought to be critically involved in the recognition and discrimination of visual objects. Using retrograde tr ansneuronal transport of herpes simplex 1, we have found that one of t he output nuclei of the basal ganglia, the substantia nigra pars retic ulata, projects via the thalamus to TE. Thus, TE is not only a source of input to the basal ganglia, but also is a target of basal ganglia o utput. This result implies that the output of the basal ganglia influe nces higher order aspects of visual processing, In addition, we propos e that dysfunction of the basal ganglia loop with TE leads to alterati ons in visual perception, including visual hallucinations.