Hubert R. Dinse of Ruhr-University Bochum in Germany and his colleagues outfitted 16 subjects with small discs on the tip of the right index finger that applied subtle pressure for three hours. Such stimulation triggers what is known as co-activation, in which additional neurons are recruited to the brain's somatosensory cortex to process the increased amount of tactile information. Scientists can quantify the sense of touch by determining the distance between two pins at which a person can no longer distinguish that there are two separate points pressing on his fingertip. The researchers found that after stimulation subjects performed 12 percent better on average than people who had not worn the disk. What is more, when participants were also given amphetamines, this improvement doubled.
The enhanced sense of touch only lasted about 24 hours, the team reports, but additional stimulation raised it again. Dinse notes that for rehabilitation regimens the improved sensory reception would need to be more durable and long-lasting, and his team is now investigating possible ways to achieve this.