A comparison of stimulus synchronous activity in the primary motor cortices of athletes and non-athletes.

In this study, we measured primary motor cortex (MI) activity during a reaction time task to examine the appearance of MI activity that synchronized with the stimulus presentation (stimulus synchronous MI activity, SSMA). Because brain activity was expected to be enhanced by the repetitive/extensive activation, we hypothesized that the SSMA would be more clearly observable in athletes who were trained to perform reactive movements than in non-athletes. MI activity was measured in ten athletes and ten non-athletes by magnetoencephalography. The tasks were a simple reaction task and a Go/Nogo reaction task in which the subjects were asked to abduct their right index fingers in response to a visual stimulus. The Go/Nogo reaction time task was adopted to confirm the presence of the SSMA, because the MI activity in response to a Nogo stimulus did not overlap with the MI activity that was synchronous with the execution of the movement. The results show that the SSMA was clearly apparent in the athlete group (9/10). In the non-athlete group, however, only three subjects showed the SSMA (3/10). Moreover, the MI activity of the athletes tended to be larger than that of the non-athletes, even though the athletes did not specifically practice these index finger movements during their daily training. We concluded that long-term physical training promotes MI activity and the effects of reactive task repetition were more clearly apparent in the MI activity of the athletes.