LC neuronal impulse activity during the rest (A, C) and active periods (B, D). Average impulse activity was greater during the active period than during the rest period in LC neurons. Raw traces (A, B) and composite firing frequencies (C, D) of LC neural responses to local microinfusion of the orexin 1 receptor antagonist SB334867-A (upper traces in A and B are pre-microinfusion and lower traces are during microinfusion). Whereas no significant change in firing was observed in average LC activity with SB-334867-A microinfusion during the rest period, SB-334867-A microinfusion during the active period significantly decreased LC firing frequencies . Each line in panels C and D indicates data from a single neuron.