This study aims to investigate the change in the excitability of spinal neural function by measuring differences in the F waves recorded with various observation targets for healthy subjects. The F wave was first recorded at rest, and then recorded for one minute while the subject observed a video after a four-minute rest period. The F wave is elicited from the right thenar eminence. [Experiment 1] The video was presented in three conditions: the right thumb at rest (condition A), movement of the right thumb (condition B), and movement of the right foot (condition C). The findings for the three conditions were then compared. Results revealed that the relative F wave persistence was significantly higher in condition B than in condition A. Furthermore, the relative amplitude of the F/M ratio was significantly higher in condition B than in conditions A and C. [Experiment 2] The video was presented in two conditions: movement of the right thumb (condition D), movement of the left thumb (condition E). The findings for the two conditions were then compared. Results revealed that the relative F wave persistence and amplitude of the F/M ratio were significantly higher in condition D than in condition E. These results suggest that the excitability of spinal neural function, which corresponds to the muscle on the right thenar eminence, is increased by the observation of the right thumb movement, but that is not changed by the observation of the left thumb movement.

High-frequency oscillations (HFOs) are defined as electroencephalographic activity at frequencies over 80 Hz. To record HFOs, a sampling frequency at or above 2 kHz and anti-alias filtering at or above 600 Hz is recommended. HFOs can be recorded using clinical macroelectrodes. Visual identification of HFOs can be achieved by high-pass filtering, increasing sensitivity, and temporally expanding the electroencephalogram (EEG). Interictal HFOs in intracranial EEGs suggest the localization of the seizure onset zone and epileptogenic zone. Ictal-onset HFOs in intracranial EEGs may be helpful in improving seizure outcome after epilepsy surgery. Epileptic encephalopathies in children show many interictal HFOs in scalp EEGs, and these HFOs may contribute to the development of cognitive deficits in this condition. Clues for differentiating pathological HFOs from physiological HFOs include the presence or absence of accompanying spikes, a different coupling pattern with slow waves, and different suppression patterns during rapid-eye-movement sleep.