Figure 12.

Serotonin and SP released from n. raphé obscurus depolarize inspiratory XII motoneurons and pre-BötC neurons in slices. A, Whole-cell current-clamp recording of XII motoneuron that depolarized in response to focal microinfusion of aCSF with elevated K⁺ (15 mm) into the n. raphé obscurus to stimulate serotonin neurons. CNQX (20 μm) was present in the bath. This depolarization was partially blocked by bath-applied ketanserin (7.5 μm) and further attenuated by coapplying SR 140333 (7.5 μm). B1, Example of intrinsically bursting pre-BötC neuron that was depolarized by raphé stimulation. This first augmented the intrinsic bursting frequency and then reversibly transformed the firing pattern from bursting to tonic spiking. B2, In the same neuron as B1, bath-applied KET (7.5 μm) decreased the initial burst frequency (left) and attenuated the effect of raphé stimulation (middle). B3, In the same neuron, coapplication of SR 14033 (7.5 μm) further reduced the initial bursting frequency relative to KET alone (left, note the change in time scale relative to B2) and nearly abolished the excitation that occurred during raphé stimulation (middle).