By Helen Mizrach
The biological mechanism behind the physical sensation of tickling has not been precisely defined. However, a new study on the perception of tickling in rats has identified a brain area that may be involved. Researchers Shimpei Ishiyama and Michael Breht investigated the response of a rat’s brain to tickling. Earlier studies found that young rats responded with 50kHz ultrasonic laughter-calls when tickled by humans in a laboratory. In this new study, the rats also responded avidly to the researchers’ tickling by emitting many ultrasonic calls and jumping around, especially when tickled on the feet and/or belly. The investigators looked at the rats’ somatosensory cortex during this time, and found that nerve cells in the cortex’s trunk region were highly active during the tickling process. The researchers noted that a similar brain response occurred when the rats were involved in play behaviors. Conversely, when the rats were made anxious (and therefore less ticklish), the activity in these cells decreased. These results suggest that activity in the trunk somatosensory cortex of the rat brain may play a major role in producing the ticklish sensation in rats. Professor Michael Brecht believes that ticklishness itself is a brain-trick that rewards interaction and play with others. This new finding is one step in the right direction towards mapping out the biological mechanism behind tickling across multiple species.
Humboldt-Universität zu Berlin. (2016, November 10). Why are we ticklish? Rats are surprisingly ticklish when their mood is right. ScienceDaily. Retrieved November 21, 2016 from www.sciencedaily.com/releases/2016/11/161110152342.htm