[T]he patient started … disrobing in front of others, manipulating her genitals, and making sexual advances toward her father. She would lick any object lying on the ground and whenever she got an opportunity, she would rush to the toilet and try to put urine and feces into her mouth (urophagia and coprophagia, respectively).
In another case, an epileptic woman underwent an unsuccessful left temporal lobectomy to help stop debilitating seizures. Klüver-Bucy symptoms, including hypersexuality, emerged following the surgery. She began masturbating in public and aggressively soliciting her family members and neighbors for sex. After having another seizure, she was brought to the emergency room, where, after a half hour in the waiting area, she began performing fellatio on an elderly cardiac patient. (This may or may not be one of the few examples where one person's syndrome is another's lucky day; it's also unclear if this was a display of hypersexuality or hyperorality, but it's inevitable, perhaps, that the twain should occasionally meet.)
Other temporal-lobe epileptics have also exhibited hypersexuality in the "postictal" state, which is the period of recovery time following a seizure. In a recent issue of Epilepsy and Behavior, New York University neurologist Vanessa Arnedo and her colleagues present the case of a 39-year-old man who began having semi-frequent seizures during the middle of the night. After nocturnal convulsions, he'd sleep for another 10 minutes, wake up, and then rape his wife. (In the authors' more delicate wording, he was described as "becoming sexually aggressive toward his wife by forcing intercourse.") Importantly, however, "the tremendous remorse and abhorrence for what he had done when he learned of his actions led him to pursue possible surgery mainly to eliminate this postictal behavior." Other people with similar epileptic profiles also become hypersexualized in the postictal state. To his later horror, one man motioned for his 12-year-old daughter to join him and his wife in the bedroom following a nighttime seizure.
It is these last few examples, where Klüver-Bucy Syndrome manifests in criminal behavior, such as rape or child molestation, that our materialistic convictions are really put to the test. In 2003, University of Virginia neurologists Jeffrey Burns and Russell Swerdlow described how an otherwise well-behaved, 40-year-old man developed a case of "new-onset pedophilia" after suffering the appearance of a right orbitofrontal tumor. The man denied any pre-existing interest in children; he did have a predilection for pornography before the tumor, say Burns and Swerdlow, but now he was downloading child porn and making subtle sexual advances to his prepubescent stepdaughter. His hypersexuality applied to full-grown women, too—so much so, in fact, that he couldn't keep himself from fondling female nurses and staff during a neurologic examination. Long story short, when the man's tumor was removed, his prurient interests and behaviors all but disappeared, and since he was no longer deemed a threat to his stepdaughter, he returned home. But his headaches returned, his tumor regrew, and so did the criminal impulse. A "re-resection" of the tumor was accomplished, the man became a good citizen again, and, as far as we know, that remains true today. (In a more recent case co-published by famed neuroscientist Oliver Sacks, and neatly summarized by the Neuroskeptic blog, a 51-year-old man without any criminal history had a portion of his right temporal lobe removed to prevent seizures. Following this, he developed telltale signs of Klüver-Bucy, including hypersexuality. His was another case of "new-onset pedophilia" but as Sacks laments, in spite of this he was nevertheless sentenced to several years in prison for downloading child porn.)
What's the take-away message? I'll let you do the hard work of thinking through the implications for our belief in free will and how it might or might not apply. But another intriguing question emerges, too: If a "good" person's brain can be rendered morally disabled by an invasive tumor or an epileptic fuse-shortage, subsequently causing them to do very bad deeds, then isn't it rather hypocritical to assume that a "bad" person without brain injury—whose brain is anatomically organized by epigenetics (the complex interplay between genes and experiences)—has any more free will than the neuroclinical case? After all, perhaps it's just a matter of timing: The "good" are born with brains that can "go bad," whereas the "bad" are hogtied by a morally disabled neural architecture from the very start. And although it may be less common, if a "bad" person behaves in an upstanding manner, could that be the result of fortuitous brain damage or epilepsy, too?
It's all brain-based in the end, including the parameters by which one can contemplate and, especially, execute their free will. Perhaps we're only as free as our genes are pliable in the slosh of our developmental milieus.