Uniform Inhibition of Dopamine Neurons in the Ventral Tegmental Area by Aversive Stimuli

TLDR

Dopamine neurons are central to reward processing, and theories predict they are inhibited or unresponsive to aversive stimuli. In anesthetized rats, presumed dopamine neurons excited by aversive stimuli were actually non‑dopaminergic, while true dopamine neurons were inhibited, indicating dopamine neurons respond only to reward.

Abstract

Dopamine neurons play a key role in reward-related behaviors. Reward coding theories predict that dopamine neurons will be inhibited by or will not respond to aversive stimuli. Paradoxically, between 3 and 49% of presumed dopamine neurons are excited by aversive stimuli. We found that, in the ventral tegmental area of anesthetized rats, the population of presumed dopamine neurons that are excited by aversive stimuli is actually not dopaminergic. The identified dopamine neurons were inhibited by the aversive stimulus. These findings suggest that dopamine neurons are specifically excited by reward and that a population of nondopamine neurons is excited by aversive stimuli.