Phasic responses in dorsal raphe serotonin neurons to noxious stimuli

Serotonin is widely implicated in aversive processing. It is not clear, however, whether serotonin neurons encode information about aversive stimuli. We found that, in the dorsal raphe of anesthetized rats, most neurochemically-identified clocklike serotonin neurons were phasically excited by noxious footshocks, whereas most bursting serotonin neurons were inhibited. These results suggest that discrete groups of serotonin neurons differentially code for aversive stimuli.

Research highlights▶ Clocklike DRN neurons are neurochemically heterogeneous. ▶ Clocklike serotonin neurons are excited by noxious footshocks. ▶ Bursting DRN neurons are uniformly serotinergic. ▶ Bursting serotonin neurons are inhibited by noxious footshocks.