Corticostriatal terminals, which are primarily from the layer-five and deep-layer-three pyramidal neurons are distributed in a patchy manner.70,71 This patchy pattern is consistent with patterns found with other afferent projections as well as with transmitter-related compounds. Whereas the VS is associated with emotion, the caudate nucleus with cognition, and the putamen with sensorimotor function, it is important to remember that there is no clear boundary between the VS and DS, and the separation between the caudate nucleus and the putamen is merely a structural one, based solely on the IC separation, not a functional one. The distribution of terminals from the cortex is generally organized topographically (Figure 3). Thus, prefrontal areas project primarily to the VS and rostral caudate nucleus and putamen. Sensorimotor areas project more caudally, primarily to the putamen. These distributions form the basis for the idea of parallel and segregated cortico-basal ganglia circuits. However, when terminals from various cortical areas are examined closely, it clearly demonstrates extensive convergence of inputs from different functional regions. This actually creates a complex interface between inputs from functionally distinct regions. Indeed,
