Dopamine Gates Visual Signals in Monkey Prefrontal Cortex Neurons.

The neurotransmitter dopamine, which acts via the D1-like receptor (D1R) and D2-like receptor (D2R) family, may play an important role in gating sensory information to the prefrontal cortex (PFC). We tested this hypothesis in awake macaques and recorded visual motion-direction tuning functions of single PFC neurons. Using micro-iontophoretic drug application combined with single-unit recordings, we simulated receptor-specific dopaminergic input to the PFC and explored cellular gating mechanisms. We find that stimulating D1Rs, and particularly D2Rs, enhances the single-neuron and population coding quality in PFC neurons. D2R stimulation causes a clear increase of the neurons' responses to the preferred motion direction and a decrease to the non-preferred motion direction, thus enhancing neuronal signal-to-noise ratio. Neither D1R nor D2R stimulation had any impact on the neurons' tuning sharpness. These results elucidate the mechanisms of how receptor-specific dopamine effects can act as a gating signal that enables privileged access of sensory information to PFC circuits.