Tactile coactivation resets age‐related decline of human tactile discrimination

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Abstract
Objective For young subjects, it is well‐documented that training and practice improve sensorimotor performance. However, little is known about how the typically observed age‐related decline of sensorimotor abilities can be ameliorated by sensory stimulation. Methods As an alternative approach to training, we have introduced a tactile coactivation protocol involving Hebbian synaptic plasticity to improve tactile performance on a short timescale of a few hours. Results By applying coactivation on the index finger to drive perceptual learning, we demonstrate that in the elderly, aged 65 to 89 years, the age‐related impairment of tactile two‐point discrimination can be mitigated substantially. In elderly adults, tactile‐acuity thresholds increased to 3.5mm compared with 1.5mm found in young adults, whereas 50‐year‐old subjects showed intermediate performance. As a result of coactivation, discrimination thresholds of the 80‐year‐old adults came to match those typically found at an age of 50, demonstrating that age‐related decline in tactile performance is not irreversible, but rather subject to considerable restoration by specific stimulation protocols. Interpretation Because the preservation of sufficient tactile acuity into advanced age is an important prerequisite for the maintenance of autonomous living, we believe that the concept of coactivation might turn out to be beneficial in preserving everyday sensorimotor competence in the elderly through new forms of therapeutic interventions. Ann Neurol 2006.