Speech and laughter are uniquely human. Although there is considerable information on the neuronal representation of speech, little is known about brain mechanisms of laughter. Here we report that electrical stimulation in the anterior part of the human supplementary motor area (SMA) can elicit laughter. This area is also involved in the initiation of speech and has been shown to have increased activity in people who stutter. Electrical stimulation was applied at 85 discrete sites on the cortical surface of the left frontal lobe of a 16-year-old girl (A.K.) undergoing monitoring by intracranial sub-dural electrodes to locate the focus of chronic intractable seizures. The patient's seizures were never accompanied by laughter. During stimulation A.K. performed a variety of tasks including naming of objects, reading a paragraph of text, counting, rapid alternating supination and pronation of the forearms, finger-to-thumb apposition, and alternating flexion and dorsiflexion of the feet.
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