ReviewFunctional implications of dopamine D1 vs. D2 receptors: A 'prepare and select' model of the striatal direct vs. indirect pathways

•A new model of dopamine function in the basal ganglia.•Encoding of reward association strength in the direct and indirect pathways.•Direct pathways encode using LTP mechanisms.•Indirect pathways encode using receptor internalisation.•Combined these pathways operate as a 'prepare and select' system.

The functions of the D1- and D2-dopamine receptors in the basal ganglia have remained somewhat enigmatic, with a number of competing theories relating to the interactions of the 'direct' and 'indirect pathways'. Computational models have been good at simulating properties of the system, but are typically divorced from the underlying neural architecture. In this article we propose a new model which re-addresses response selection at the level of the basal ganglia. At the core of this response selection system the D1 DA receptor-expressing striatal pathways 'prepare' the set of possible appropriate responses. The D2DR-expressing striatal pathways then shape and 'select' from this initial response set framework.This article is part of a Special Issue entitled: Ventral Tegmentum & Dopamine.