Mamillary-body lesions and visual recognition in monkeys.

Cynomolgus monkeys with complete bilateral destruction of the medial mamillary nucleus exhibited little, if any, deficit in object recognition, although they did show evidence of impairment in spatial memory. The pattern of effects thus resembled that found previously after either hippocampal ablations or transections of the fornix and suggests that, like such damage, mamillary-body damage alone is insufficient to produce the global amnesia attributed to it in clinical cases.