Tickles Trigger Different Area of the Brain than Laughter Alone

It's certainly interesting how one part of our brain can trigger various emotions. However, when it comes to matters of laughter, scientists have discovered that there's something silly about the different types.

In fact, according to a new study from Germany, the area of our brain triggered by laughter from a joke is not the same area triggered by a tickle.

The study had approximately 30 participants in their 20s who were tickled by a friend or partner on their feet. As this happened, their brains were scanned in a functional magnetic resonance imaging (fMRI) machine.

Separately, participants were asked to produce a laugh voluntarily (not in response to a joke) inside an fMRI machine, which measures blood flow to different areas of the brain to provide a real-time map of brain activity.

Both ticklish laughter and voluntary laughter activated the Rolandic operculum brain region, which is located in the primary sensory-motor cortex and is involved in movements of the face; both laughter types were also linked to activity in brain regions involved in vocal emotional reactions, such as crying

However, only ticklish laughter activated the hypothalamus, a part of the brain involved in regulating many functions, including visceral reactions, the researchers said. 

Ticklish laughter also activated parts of the brain thought to be involved in anticipation of pain, which supports the idea that people who are tickled react defensively, according to researchers.

The study shows that the same brain networks are activated in earlier studies on humorous laughter. Yet, humorous laughter also activates an area of the brain involved in "higher order" functions, as well as a part of the brain called the nucleus accumbens, which is thought to be part of the brain's "pleasure center." Ticklish laughter did not activate these areas.

The results, which will be detailed in the June issue of the journal Cerebral Cortex, confirm the idea that ticklish laughter is a "building block" of humorous laughter - an idea first proposed by Charles Darwin and Ewald Hecker in the late 1800s, according to researchers.

The study was conducted by researchers at the University of Greifswald in Germany, and researchers at the University of Fribourg and University of Basel in Switzerland.