Human movement-related brain potentials preceding voluntary movements in different arousal states monitored with skin potential level.

The present study investigated the readiness potential (RP) preceding a brisk extension of the right middle finger during different arousal states as monitored by skin potential level (SPL). The late component of the readiness potential in the medium arousal state was significantly larger than those in the low and high arousal states. This finding indicates that the RP waveform may vary as a function of arousal states, suggesting the inverse U-shaped relationship proposed in studies of the contingent negative variation.