Age-related changes in intrahemispherical interactions within motor areas of the brain

Background: Several studies examined the effects of intracortical inhibition during a motor task but the evidence between younger adults and elderly is limited. Objectives: The aim of our experiment is to explore the influence of aging on the intracortical inhibitory system during a motor reaction task in healthy subjects measured by TMS. Participants: Fifty-three subjects were recruited by advertising in public places in and around Leuven and were divided into two groups based on age. The first group of aged between 18-30 (n=25) and the second group were the elderly of 65-77 years old (n=28). Measurements: Subjects had to perform a choice reaction task (CRT), which required different responses of right and left index finger. Short-interval intracortical inhibition (SICI) was used to measure intracortical inhibition. Timing of TMS pulses were semi-randomized at three different timings during the experiment, in the preparation period at the warning signal (WS) or the imperative signal (IS), and in the action selection period at 75% of the EMG activity onset.