Primate dopamine neurons activated in rewarding environment by tonic disinhibition from amygdala

Abstract

Seeking out good and avoiding bad objects is critical for survival. In practice, objects are rarely good every time or everywhere, but only at the right time or place. Whereas the basal ganglia (BG) are known to mediate goal-directed behavior, for example, saccades to rewarding objects, it remains unclear how such simple behaviors are rendered contingent on higher-order factors, including environmental context. Here we show that amygdala neurons are sensitive to environments and regulate dopamine (DA) neurons via an inhibitory projection to substantia nigra pars reticulata (SNr) neurons. We combined optogenetics and multi-channel recording to demonstrate that rewarding environments induce tonic firing changes in DA neurons. These tonic responses are mediated by disinhibition via GABAergic projection onto DA neurons from SNr, which in turn are suppressed by inhibitory projection from the amygdala. Thus, the amygdala provides an additional source of learning to BG circuits, namely contingencies imposed by the environment.