FIG. 3.

Facilitatory combination-sensitive neuron displayed transient hyperpolarization in response to high- but not low-frequency stimuli. A: delay-tuned spike response. This neuron was facilitated when the low-frequency sweep preceded the high-frequency sweep by 2–8 ms. B: PSTHs display spike response to different stimuli. C: averaged trace (n = 6) in response to stimuli indicated above B. Average resting membrane potential = −75 mV. No evidence of low frequency–evoked hyperpolarization was observed, but the HI stimulus clearly evoked hyperpolarizing responses. D: 3 consecutive voltage traces that contributed to the averaged trace. Spike height = 40 mV. See Fig. 2 for protocol.