Spontaneous electrical activity of a trigeminal mesencephalic neuron responsive to fan-like movement of the macrovibrissae bundle and to masseter muscle stretching. (A) Spontaneous electrical activity of a TMne under baseline conditions (i.e., with the vibrissae in a resting position). (B) The same activity recorded during fan-like movement of the macrovibrissae bundle and (C) during both fan-like whisker movements and masseter muscle stretching. "On" and "off" arrows show the start and the stop of the masseter stretch, respectively. Calibrations: horizontal 0.5 s; vertical 250 μV.