LONDON Speech and laughter are controlled by the same area of the brain which probably evolved for such uniquely human characteristics, U.S. researchers said on Wednesday. Itzhak Fried and colleagues at Ucla Medical School in Los Angeles said they found they could induce a 16-year-old epileptic patient to laugh by electrically stimulating the part of the brain normally involved in speech and manual dexterity.

Our observations suggest that smiling and laughter might involve similar mechanisms and are closely related phenomena on a single continuum, Fried said in a letter to the scientific journal Nature. Fried was stimulating the brain of the teenage girl to find out why she had chronic seizures when he noticed that a small part of the supplementary motor area (SMA) of the brain consistently produced laughter.

Each time the stimulation evoked laughter the teenager, who awake during the trials, attributed it to whatever she was doing at the time or to the people in the room with her. The duration and intensity of the laughter corresponded with the level of stimulation. Fried said: We propose that the anterior part of the SMA is part of a further development in humans to accommodate the specialized functions of speech, manual dexterity and laughter.

(Reuter)