Mechanism of dopamine traveling waves in the striatum: theory and experiment

Striatal dopamine (DA) encodes reward, with recent work showing that DA release occurs in spatiotemporal waves. However, the mechanism of DA waves is unknown. Here we report that the striatal cholinergic neuropil also exhibits wave-like activity, and that the spatial scale of striatal DA release is extended by nicotinic receptors. Based on these findings we hypothesized that the local reciprocal interaction between cholinergic interneurons (CIN) and DA axons suffices to drive endogenous traveling waves. We show that the morphological and physiological properties of the CIN-DA interaction can be modeled as a reaction-diffusion system that gives rise to traveling waves. Analytically-tractable versions of the model show that the structure and the nature of propagation of CIN and DA traveling waves depend on their coupling, and that traveling waves can give rise to empirically observed correlations between these signals. Our model provides a biophysical mechanism for wave formation and predicts that the observed DA and CIN waves are strongly coupled phenomena.