The list of symptoms generally include the following:
Docility, characterized by exhibiting diminished fear responses or reacting with unusually low aggression. This has also been termed "" or "tameness".
Dietary changes and hyperphagia, characterized by eating inappropriate objects, or overeating, or both.
Hyperorality, described by Ozawa et al. as "an oral tendency, or compulsion to examine objects by mouth".
Hypersexuality, characterized by a heightened libido or a tendency to seek sexual stimulation from unusual or inappropriate objects.
Visual agnosia, characterized by an inability to recognize familiar objects or people.
While this cluster of syndromes is common to such sources as 1997's The Neuropsychiatry of Limbic and Subcortical Disorders, 2005's Functional Neuroanatomy: Text and Atlas and 1997's "Single-Photon Emission CT and MR Findings in Klüver-Bucy after Reye syndrome", an article in the American Journal of Neuroradiology, the three vary thereafter. Inconsistent criteria include:
Hypermetamorphosis, characterized by Ozawa et al. as "an irresistible impulse to notice and react to everything within sight". This is included under the classification systems described by The Neuropsychiatry of Limbic and Subcortical Disorders and "Single-Photon Emission CT and MR Findings in Klüver-Bucy".
Amnesia, characterised by an inability to recall memories. This only occurs when the damage extends bilaterally into the hippocampus.
As part of an investigation by Heinrich Klüver in the 1930s into the area affected by mescaline, Klüver arranged to have the temporal lobes of a number of rhesus monkeys bilaterally removed by Paul Bucy, a neurosurgeon. Klüver did not find the expected impact in response to mescaline, but did observe a series of changes in the subject animals. The six points of difference that Klüver recorded were visual agnosia, an increased tendency to explore items by mouth, hypermetamorphosis, dampening of emotional expression, altered sexual behavior and differences in diet. Klüver later discovered similar observations by Sanger Brown and Edward Albert Sharpey-Schafer that had been published in 1881 and drew on these to substantiate his own observations. Monkeys in the Klüver-Bucy experiment evidently had normal vision and motor skills, but exhibited "psychic blindness", what Rusiko Bourtchouladze described in 2004 as an inability to recognize "the emotional importance of events". They did not display fear for items that would ordinarily frighten members of their species; they displayed an appetite for improper foods such as rocks or live rats and sought intercourse with unusual partners, including members of other species. They became extremely interested in exploring items in their environment and became when approached.
In humans
Klüver–Bucy syndrome was first documented among certain humans who had experienced temporal lobectomy in 1955 by H. Terzian and G.D. Ore. It was first noted in a human with meningoencephalitis in 1975 by Marlowe et al. Klüver–Bucy syndrome can manifest after either of these, but may also appear in humans with acute herpes simplex encephalitis or following a stroke. Other conditions may also contribute to a diagnosis of Klüver–Bucy syndrome, including Pick's disease, Alzheimer's disease, ischemia, anoxia, progressive subcortical gliosis, Rett syndrome, porphyria and carbon monoxide poisoning, among others. It is rare for humans to manifest all of the identified symptoms of the syndrome; three or more are required for diagnosis. Among humans, the most common symptoms include placidity, hyperorality and dietary changes. They may also present with an inability to recognize objects or inability to recognize faces or other memory disorders. Social neurosciences research shows that changes in temporal lobe is identified as a cause for aberrant sexual and hyper-sexual behaviors.
Klüver–Bucy syndrome was featured in the Radiolab episode, "Blame." The lead story featured a man who developed Klüver–Bucy syndrome after his second neurosurgery for epilepsy. The story was revisited by Radiolab in June 2017 augmented with further discussion with neurologist Dr. Sapolsky, who addresses the syndrome and the associated legal significance of neurological defenses. Klüver–Bucy syndrome was featured in the Black Box episode, "The Fear," the episode "Taboo" of the TV series Criminal Minds, the episode "Whistleblowers" of the TV series Blue Bloods, and the episode "Comfort's Overrated" of the TV series Royal Pains.
