Our overarching goal is to examine with transcranial direct current stimulation (tDCS) how age and expertise affect the mutual balance between excitation and inhibition within the somatosensory cortex. Tactile perception contributes importantly to manual dexterity and therefore to the mastering of many activities of daily living. Impairment of tactile perception in older age often results in loss of independence. However, age-related decline in tactile performance can be delayed or prevented by training and acquisition of tactile expertise in middle adulthood, for example on the job. Tactile aging is accompanies by alterations on the neural level which can be observed as changes in early (somatosensory) and late (cognitive) ERP components.
Interestingly also these changes in ERP components seem to be reversible of delayed by tactile expertise. Supposedly, an altered balance between local excitation and inhibition play an important role in these processes. Although expertise and aging have been suggested to have different effects on inhibition and excitation during perception and learning, namely a focal increase of excitation with expertise and a decrease of lateral inhibition with aging, is seems that these different effects on the synaptic level have similar effects on the EEG measures. This question we want to further examine with this follow-up study to the Bremen Hand Study @ Jacobs. For this purpose we will use tDCS to modulate intracortical excitation and inhibition within the somatosensory cortex.