Dopamine D1 receptor signalling differentially regulates action sequences and turning behaviour in freely moving Drosophila

Abstract

Here, we introduce a novel behavioural paradigm to study neural circuits and mechanisms underlying action selection and decision-making in freely moving Drosophila. We first validate our approach by studying FoxP mutants and show that normally invariant patterns of motor activity and turning behaviour are altered in these flies, reminiscent of indecision. Then, focusing on central complex (CX) circuits known to integrate different sensory modalities and controlling premotor regions, we show that action sequences and turning behaviour are regulated by dopamine D1 (Dop1R1) receptor signalling. Dop1R1 inputs onto CX columnar wedge and ellipsoid body R2/R4m ring neuron circuits both negatively gate motor activity but inversely control turning behaviour. While flies deficient of D1 receptor signalling present normal turning behaviour despite decreased activity, restoring Dop1R1 level in R2/R4m-specific circuitry affects the temporal organisation of motor actions and turning. These findings suggest that columnar wedge and ring neuron circuits of the CX differentially modulate patterns of motor action sequences and turning behaviour by comparative Dop1R1 signalling for goal-directed locomotion.