Corticostriatal connections of the superior temporal regions in the macaque monkey

Corticostriatal connections of auditory areas within the rostral and caudal portions of the superior temporal gyrus (STG) and in the supratemporal plane (STP) of pigtail macaque (Macacca nemestrina) were studied with particular emphasis on specific projections to the ventral striatum. Retrograde tracers were injected into five different regions of the ventral striatum such as the ventromedial caudate nucleus, ventral shell, central shell, dorsal core of the nucleus accumbens (NA), and ventrolateral putamen to identify the cells of origin. There were only few projections from the auditory areas in the STP to the ventral striatum. However, the association (or belt) areas of the STG collectively had widespread corticostriatal projections characterized by differential topographic distributions. The rostral parts of the STG strongly projected to the ventromedial caudate nucleus. The mid‐portion of the STG also projected to the same ventral striatal regions, but the connections were relatively less extensive. Interestingly, the caudal portion of the STG had no connection to all subregions of the ventral striatum. These differential patterns of corticostriatal connectivity suggest that the ventromedial caudate nucleus would be a major auditory convergence area and mainly involved in sound recognition rather than spatial localization of sound sources.