Local desensitization to dopamine devalues recurring behavior

Abstract

Goal achievement adjusts the relative importance of future behaviors. We use Drosophila to study this form of motivational control, finding that prior matings make males increasingly likely to abandon future copulations when challenged. Repetition-induced devaluation results from a reduction in dopamine reception by the Copulation Decision Neurons (CDNs), which mediate the decision to end matings. Dopamine signaling to the CDNs sustains matings in real time, but also triggers a lasting, β-arrestin-dependent desensitization of the D2R on the CDNs, leaving subsequent matings susceptible to disruption. When D2R desensitization is experimentally prevented, the male treats each mating as if it were his first. These findings provide a generalizable mechanism of motivational control and reveal a natural function for the long-studied susceptibility of the D2R to drug-induced inactivation.