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How are we ticklish? The answer to this question has long eluded us. Ishiyama & Brecht’s intriguing study has further explored the origins of modalities of ticklishness.

Rats emit a 50MHz vocalisation when tickled, which can be taken as a primitive form of joy. This vocalisation was used to map neuronal fi ring rates in response to different sensory inputs – via touch, play and the effects on this of anxiety. In this way, the researchers correlated the sensory input and tickling response to neuronal centre output. This study mapped the tickling response to the somatosensory cortex, showing similar vocalisations and tickling behavioural patterns can be found in rats and humans.

Read the full article in Science 354 757–760