Figure 3.

Computer-generated maps of the distribution of spindle neurons in the anterior cingulate cortex. All maps show a level situated at the genu of the corpus callosum in the human (A), bonobo (B), common chimpanzee (C), gorilla (D), and orangutan (E). The spindle cells are restricted to layer Vb and show much higher numbers in human and the two chimpanzee species, whereas fewer are seen in gorilla and orangutan. No spindle cells are observed in the white-handed gibbon (F), long-tailed macaque monkey (G), and owl monkey (H). The maps are approximately to scale. The darkly shaded areas in B reflect local damage to the superficial layers of the specimen. The caudate nucleus is shaded darkly in H. CC, corpus callosum; CS, cingulate sulcus.