Giving new meaning to “sensitivity training,” scientists have developed a simple way to greatly enhance the human body’s ability to feel subtle sensations.
The enhanced sensitivity, achieved with a tiny stimulating device and a single dose of a drug, has reversed fingertip numbness in older people, many of whom have trouble performing everyday tasks such as buttoning shirts or turning switches on and off. Researchers said they suspect it could also help blind people read Braille. And applying the technique to the feet might prevent falls in diabetics who have lost sensation in their toes, which are crucial for balance.
The ability to boost sensory sensitivity, scientists said, could even allow people with normal function to achieve bionic supersensitivity — for work or recreational purposes — enhancing the senses of taste or smell or adding to the tactile pleasure of a romantic caress.
“This indicates that the sensitivity we typically see in normal subjects is not a physical limit,” said Hubert R. Dinse, the neuroscientist who led the work at the Ruhr-University Bochum in Germany.
The new work, described in today’s issue of the journal Science, is the latest in a series of advances that have demonstrated an unexpected capacity to reverse sensory declines in the elderly and enhance those functions in younger people.
Studies have shown that repeated exposure to subtle signals — such as barely perceptible changes in musical tones — can improve sensitivity to those signals, a form of sensory enhancement that has been documented in musicians. Research has shown that these enhanced abilities are the result of the brain gradually reconfiguring itself to devote larger portions to the task at hand. In taxi drivers, for instance, the brain’s hippocampus — which maintains mental maps and a sense of place in the world — grows larger.
Until now, however, scientists did not know how the body translated musical practice, taxi driving or other sensory experiences into anatomical changes in the brain. The new study shows for the first time that the process involves a biochemical pathway already known to play a key role in learning and memory. When scientists gave subjects a drug that “revs up” this pathway, it vastly increased the amount of brain reorganization — or “remodeling” — that occurred during sensory stimulation, and significantly added to the improvement in function.