Klüver-Bucy syndrome

Klüver-Bucy syndrome is a behavioral disorder that occurs when both the right and left medial temporal lobes of the brain malfunction.

In rhesus monkeys
The syndrome is named for Heinrich Klüver and Paul Bucy, who removed the temporal lobe bilaterally in rhesus monkeys in an attempt to determine its function. This caused the monkeys to develop visual agnosia, emotional changes, altered sexual behavior, hypermetamorphosis and oral tendencies.

Though the monkeys could see, they were unable to recognize even previously familiar objects, or their use. They would examine their world with their mouths instead of their eyes ("oral tendencies") and developed a desire to explore everything ("hypermetamorphosis").

Their overt sexual behavior increased dramatically ("hypersexualism"), and the monkeys indulged in indiscriminate sexual behavior including masturbation, heterosexual acts and homosexual acts.

Emotionally, the monkeys became dulled, and their facial expressions and vocalizations became far less expressive. They were also less fearful of things that would have instinctively panicked them in their natural state, such as humans or snakes. Even after being attacked by a snake, they would willingly approach it again. This aspect of change was termed "placidity".

In humans
People with lesions in their temporal lobes show similar behaviors. They may display oral or tactile exploratory behavior (socially inappropriate licking or touching); hypersexuality; bulimia; memory disorders; flattened emotions (placidity); and an inability to recognize objects or inability to recognize faces.

The full syndrome rarely, if ever, develops in humans. However, parts of it are often noted in patients with extensive bilateral temporal damage caused by herpes or other encephalitis and dementias of degenerative or post-traumatic etiologies.

This disorder may be caused by many conditions, including facial or cerebral trauma; infections; Alzheimer's disease; Niemann Pick disease of the brain; or cerebrovascular disease.