Central cancellation of self-produced tickle sensation

A self-produced tactile stimulus is perceived as less ticklish than the sam e stimulus generated externally. We used fMRI to examine neural responses w hen subjects experienced a tactile stimulus that was either self-produced o r externally produced. More activity was found in somatosensory cortex when the stimulus was externally produced. In the cerebellum, less activity was associated with a movement that generated a tactile stimulus than with a m ovement that did not. This difference suggests that the cerebellum is invol ved in predicting the specific sensory consequences of movements, providing the signal that is used to cancel the sensory response to self-generated s timulation.