Disinhibition syndromes, ranging from mildly inappropriate social beha
vior to full blown mania, may result from lesions to specific brain ar
eas. Several studies in patients with closed head injuries, brain tumo
rs, stroke lesions, and focal epilepsy have demonstrated a significant
association between disinhibition syndromes and dysfunction of orbito
frontal and basotemporal cortices of the right hemisphere. Based on th
e phylogenetic origin of these cortical areas and their main connectio
ns with dorsal regions related to visuospatial functions, somatosensat
ion, and spatial memory, the orbitofrontal and basotemporal cortices m
ay selectively inhibit or release motor, instinctive, affective, and i
ntellectual behaviors elaborated in the dorsal cortex. Thus, dysfuncti
on of these heteromodal ventral brain areas may result in disinhibited
behaviors.