Kimura & Kohara: F6 EP noise and EP spike

Spontaneous activity recorded from the tibialis anterior (TA) in a healthy volunteer. High-frequency endplate (EP) spikes characteristically discharge very irregularly often associated with a low-amplitude EP noise in the background. The initially negative biphasic spikes represent single muscle fiber potentials recorded by needle tip placed near the nerve terminals. The initially positive triphasic waveform may result if the shaft rather than the tip of the needle register the same discharge. In this recording, EP spikes, 2 ms in duration, exceed the measurement limit of 500 µV, indicating a close proximity between the tip of the recording electrode and the generator source.