Selective reduction by dopamine of excitatory synaptic inputs to pyramidal neurons in primate prefrontal cortex.

We have employed in vitro physiological methods to investigate dopaminergic modulation of excitatory synaptic transmission in monkey prefrontal cortex (PFC) circuits. We show that combined activation of D1-like and D2-like dopamine receptors results in the reduction of extracellular stimulation-evoked isolated EPSCs in layer 3 pyramidal neurons. Using paired recordings from synaptically connected pyramidal neurons we have determined the basic properties of unitary synaptic connections between layer 3 pyramids in the primate PFC and, interestingly, we found that dopamine does not reduce synaptic transmission between nearby pairs of synaptically coupled PFC pyramidal neurons. This input specificity may be a critical aspect of the dopaminergic regulation of recurrent excitatory circuits in the PFC.