Cognitive representations of intracranial self-stimulation of midbrain dopamine neurons depend on stimulation frequency
Samuel J. Millard, Ivy B. Hoang, Savannah Sherwood, Masakazu Taira, Vanessa Martínez Reyes, Zara Greer, Shayna L. O’Connor, Kate M. Wassum, Morgan H. James, David J. Barker, Melissa J. Sharpe
Abstract
Dopamine neurons in the ventral tegmental area support intracranial self-stimulation (ICSS), yet the cognitive representations underlying this phenomenon remain unclear. Here, 20-Hz stimulation of dopamine neurons, which approximates a physiologically relevant prediction error, was not sufficient to support ICSS beyond a continuously reinforced schedule and did not endow cues with a general or specific value. However, 50-Hz stimulation of dopamine neurons was sufficient to drive robust ICSS and was represented as a specific reward to motivate behavior. The frequency dependence of this effect is due to the rate (not the number) of action potentials produced by dopamine neurons, which differently modulates dopamine release downstream.