On the basis of observations of how we interpret the sensation of a simple finger-tap, researchers have advanced our understanding of how the brain sorts important, externally-derived sensations, such as those created by an insect crawling on the skin, from unimportant, internally-derived sensations, such as the brush of one's own hand.
The new study is reported in the June 21 issue of Current Biology by researchers Paul Bays and Daniel Wolpert of University College London and Randy Flanagan of Queen's University, Canada.
Our senses are constantly inundated with information from which the brain must select the most important in order to guide our behavior. Because the brain is interested in novel information, it tends to discount sensations that result directly from our own actions, such as when we touch one part of our body with another. It has been suggested that a brain mechanism predicts these sensory signals in advance and attenuates them before they reach awareness. This may explain, for example, why the sensation of tickling yourself feels so much weaker than that of someone else tickling you.