Spontaneous electrical activity of a trigeminal mesencephalic neuron recorded under the resting condition of the vibrissae and during their spontaneous movement. (A) Frequency distribution histogram showing the spontaneous electrical activity of a trigeminal mesencephalic neuron (TMne) recorded while the macrovibrissae were under the resting condition (1); during their spontaneous movements, which lasted 3.83 min in this instance (2); and at the end of the movement, when the vibrissae returned to the resting condition (3). (B) The histogram shows the behavior of the same TMne recorded before (1), during (2), and after (3) vibrissae displacements during another episode of vibrissae whisking, which lasted 3.25 min in this case. In both histograms, "ON" and "OFF" indicate the start and the end, respectively, of the vibrissae displacement. The discharge frequency of the neuron (counts/bin) followed the increase or the decrease of the vibrissae displacement. Horizontal calibration: 50 sec, vertical calibrations: 10 counts/bin.