Diurnal Rhythms in Cholinergic Modulation of Rapid Dopamine Signals in the Striatum

Abstract

Circadian rhythms and diurnal (light/dark) entrainment are evident in many systems within the central nervous system. Dysregulation of these rhythms, including those of the dopamine system, plays a role in the etiology and symptomatology of a wide range of psychiatric disorders. We report several critical and previously undiscovered functions in the rhythms of both rapid dopamine signals and cholinergic interneurons (CIN) working in concert within the rodent striatum. First, we report dopamine signal-to-noise varies substantially across time of day and phasic signals are magnified during times in the circadian cycle when reward seeking (for food, reproduction, etc.) would be most advantageous. Second, we show CINs provide the mechanism for diurnal variation in rapid dopamine signals; by serving as a gain function to dopamine signal-to-noise that adjusts across time of day. We conclude that CINs vary their influence directly via nicotinic acetylcholine receptors located on dopamine varicosities across time of day.