However, there is also evidence that dorsal ACC plays an active, volitional role in choosing what response to make. Electrical microstimulation of discrete parts of the cingulate sulcus in macaque monkeys known as the cingulate motor areas (CMAs), which project directly to both primary motor cortex and to the ventral horn of the spinal cord, can elicit complex movements (He, Dum and Strick, 1995; Luppino, Matelli, Camarda and Rizzolatti, 1994; Matelli, Luppino and Rizzolatti, 1991; Wang, Shima, Sawamura and Tanji, 2001). Giant pyramidal Betz cells are found in posterior parts of both monkey and human cingulate sulcus, indicative of a motoric role for this region, and comparable subdivisions for the macaque CMAs can be found in the human brain based on the pattern of cytoarchitecture and functional comparisons (Braak, 1976; Picard and Strick, 1996; Zilles, Schlaug, Geyer, Luppino, Matelli, et al., 1996). Similarly, stimulation of an equivalent rostral CMA region in awake humans caused them to be unable to resist the urge to move towards and grasp objects within their range (Kremer, Chassagnon, Hoffmann, Benabid and Kahane, 2001). More than
