Pre-movement gating of somatosensory-evoked potentials by self-initiated movements: The effects of ageing and its implication

Objective: To study whether the gating effect of the self-initiated movements on the cortical somatosensory-evoked potentials (SEPs) is affected by ageing. Methods: The SEPs elicited by stimulating the right median nerve were recorded in 14 young and 16 older healthy subjects, while self-initiated movements of the right fingers were performed at 5-10 s intervals. The amplitudes of the major components of the SEPs at F3 and C3′ (2 cm posterior to C3) during the pre-movement period were analysed as the resting condition subserving the baseline. Results: The amplitudes at rest were significantly greater in the elderly than in the younger subjects. The amplitudes of P27, N35 and P45 at C3′ as well as N30 at F3 decreased significantly during the pre-movement period. However, the ratio of amplitudes in the pre-movement period to the resting period in the elderly was not significantly different from that in the younger subjects, except for the interaction of N30. Conclusions: The effect of age on the gating of N30 at F3 may indicate an altered preparatory processing of self-initiated movement in the elderly. The gating effect of older subjects at C3′ is almost comparable to that of young ones, which appears to be a compensatory mechanism to maintain the precise movements. Significance: Ageing affects the SEPs differently at rest and pre-movement gating.