Figure 1. Electrophysiological and histological identification of LC neurons. A, Slow and regular spontaneous firing during muscle rigidity. B, Long duration of noradrenergic spike. C, Fast activation followed by inhibition in response to a pinch stimulus (arrowhead) applied to the hindlimb paw. D, Histological location of tyrosine hydroxylase-positive cells near the recording track in the pontine region. GcR, GcL, EMG of gastrocnemius muscle (right side, left side); LC(R), locus coeruleus unit (right side); sp, spike; TaR, TaL, EMG of tibialis anterior muscle (right side, left side). LC(R) and unit traces in subsequent figures are computer-generated pulses marking discriminated action potentials.
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