'Ticklish' area of the brain found
Is tickle-induced laugher different from regular laughter? Scientists from the University of Greifswald (Germany), University of Fribourg (Switzerland) and University of Basel (Switzerland) have found that different parts of the brain are involved with ticklish laughter and voluntary laughter, and that tickling is not necessarily pleasurable even if it makes us laugh.
For the study, about 30 men and women in their 20s had their feet tickled while they were hooked up to a functional MRI scanner, which tracks the parts of the brain engaged during the activity. The study compared this to voluntary laughter which people were asked to produce—not in response to a joke--and found that ticklish laughter activates a different part of the brain. Both types of laughter are tied to the Rolandic operculum brain region, which is involved in movements of the face, and the part of the brain associated with vocal emotional reactions. However, the tickling laughter activated the hypothalamus, which controls a variety of functions, including visceral reactions.
Interestingly, ticklish laughter did not produce activity in the brain's "pleasure center" – the nuclear accumbens. Instead, the part of the brain associated with anticipation of pain – where the body reacts defensively – was activated.