Mismatch negativity (MMN) is a neurophysiological index that reflects automatic processing in the brain. So far, there have been few reports on the effect of exercise load on MMN. This study aimed to investigate the effect of handgrip exercise on MMN; ERP (event-related potentials) were recorded pre- and post-handgrip exercise for 20 healthy male college students (aged 20.9±1.4 years) and MMN was obtained by the difference waveforms and compared between pre- and post-handgrip exercise. No significant changes in MMN latency were observed at any site pre- and post-handgrip exercise. Frontal MMN (Fz, Cz, C3, C4) amplitude significantly reduced post-handgrip exercise; however, no significant changes were observed in temporal MMN amplitude (M1, M2). These findings suggest that performing specific force-based handgrip exercises may reduce attention switching reflected in the frontal component of MMN. Meanwhile, no significant changes were observed in the temporal component of MMN, pre- and post-handgrip exercise, suggesting that exercise had different effects on the frontal and temporal components. The results of this study are also consistent with previous research demonstrating that performing specific force-based handgrip exercises resulted in an inhibitory trend in information processing.

A frequency-dependent conduction block is a phenomenon whereby the amplitude of a compound action potential decreases as its frequency increases. In general, we observe a conduction block when the safety factor of transmission, which is defined as the ratio of driving current to threshold current, is less than 1. Many researchers have inferred that frequency-dependent conduction block can be observed because the denominator of the safety factor, which is the threshold current, increases with increasing frequency. However, it can also cause frequency-dependent conduction block that the numerator, which is the driving current, decreases with increasing frequency. Recently, I have modified the cable theory by considering the axon to be made up of a mixture of conductor and insulator, rather than pure conductor, with the notion of dielectric dispersion. The modification allows us to predict that the amplitude of current along an axon can decrease as its frequency increases. The current along an axon is the driving current, which is the numerator of the safety factor. Therefore, by applying the modified theory to conduction block phenomenon, we can easily understand how frequency-dependent conduction block occurs.