Rats Are Ticklish and Even Laugh, Depending on Their Mood

[FAM Times=Reporter Woo Ji-young] Rats have been found to be ticklish and to make laughter-like sounds when tickled.

Research has found that the brain contains a region that senses tickling and that activity in this region also appears to be associated with play.

Professor Michael Brecht and Dr. Shinpei Ishiyama of Humboldt University of Berlin recently published the findings in the online edition of the journal Science, the Asahi Shimbun reported.

It had previously been reported that young rats make laughter-like sounds when tickled.

The research team examined the rats' brain activity while tickling them.

A region associated with the sense of touch was found to respond strongly.

The same region also became more active when the researchers merely pretended to tickle them.

The tickled rats also displayed seemingly playful behavior, such as approaching a person's hand as if asking for more.

By contrast, when the rats were placed on an unstable elevated platform, exposed to bright light and tickled, they not only made no laughter-like sounds, but the same brain region also showed no heightened activity.

Rats are nocturnal and prefer dark places.

The findings are interpreted as showing that rats do not simply react to tickling; their response also depends on the setting and their mood.

Although ticklishness is presumed not to directly aid survival, most mammals respond to tickling.

Dr. Ishiyama said, "The fact that ticklishness has been preserved over the long course of evolution suggests that it may be a brain function that enables humans and animals to make contact and play with one another."

Reporter Woo Ji-young wjy@famtimes.co.kr