50 Years of Research on Dopamine’s Role in Passive Aversive Conditioning
and Extinction: A Systematic Review
Abstract
Dopamine, a catecholamine neurotransmitter, has historically been
associated with the encoding of reward, whereas its role in aversion has
received less attention. Here, we systematically gather the vast
evidence for a role of dopamine in the simplest form of aversive
learning: passive aversive conditioning and extinction. In the past,
crude methods were used to augment or inhibit dopamine in order to study
its relationship with fear conditioning and extinction. More advanced
techniques such as conditional genetic, chemogenic, and optogenetic
approaches now provide causal evidence for dopamine’s role in these
learning processes. Dopamine neurons encode fear and extinction-related
information and convey the signal via activation of D1, D2, D3, and D4
receptor sites particularly in the amygdala, prefrontal cortex, and
striatum in order to continuously form, consolidate, retrieve, and
update fear and extinction memory in a dynamic and reciprocal manner.
Based on the reviewed literature, we conclude that dopamine is crucial
for the encoding of passive aversive conditioning and contributes in a
way that is comparable to its role in encoding reward.