Single-wire recording of regional activity in the human masseter muscle

A new approach is presented for recording regional muscle responses by means of a single intramuscular wire electrode. The technique exploits differences in impedance due to the locations of the recording and indifferent electrodes and also relies upon bandpass filtering. The method is demonstrated by recording the activity of the right masseter muscle at three different sites during voluntary tooth clenching. The results indicate that satisfactory separation of regional muscle activity can be obtained and that the recorded signals can be sampled digitally for quantitative purposes. As this method for recording jaw muscle activity avoids the problem of variable interelectrode distances commonly associated with conventional bipolar wire electrodes, it is advantageous when recording from human muscles in the facial and intraoral regions.