Organization of inputs from cingulate motor areas to basal ganglia in macaque monkey

The cingulate motor areas reside within regions lining the cingulate sulcus and are divided into rostral and caudal parts. Recent studies suggest that the rostral and caudal cingulate motor areas participate in distinct aspects of motor function: the former plays a role in higher-order cognitive control of movements, whereas the latter is more directly involved in their execution. Here, we investigated the organization of cingulate motor areas inputs to the basal ganglia in the macaque monkey. Identified forelimb representations of the rostral and caudal cingulate motor areas were injected with different anterograde tracers and the distribution patterns of labelled terminals were analysed in the striatum and the subthalamic nucleus. Corticostriatal inputs from the rostral and caudal cingulate motor areas were located within the rostral striatum, with the highest density in the striatal cell bridges and the ventrolateral portions of the putamen, respectively. There was no substantial overlap between these input zones. Similarly, a certain segregation of input zones from the rostral and caudal cingulate motor areas occurred along the mediolateral axis of the subthalamic nucleus. It has also been revealed that corticostriatal and corticosubthalamic input zones from the rostral cingulate motor area considerably overlapped those from the presupplementary motor area, while the input zones from the caudal cingulate motor area displayed a large overlap with those from the primary motor cortex. The present results indicate that a parallel design underlies motor information processing in the cortico-basal ganglia loop derived from the rostral and caudal cingulate motor areas.