Background: Dopamine (DA) and serotonin (5-HT) are released in cortex under similar circumstances, and many psychiatric drugs bind to both types of receptors, yet little is known about how they interact.
Methods: To characterize the nature of these interactions, the current study used in vitro patch-clamp recordings to measure the effects of DA and/or 5-HT on pyramidal cells in layer V of the medial prefrontal cortex.
Results: Either DA or 5-HT applied in isolation increased the evoked excitability of prefrontal cortex neurons, as shown previously. Coapplication of DA and 5-HT produced either a larger increase in excitability than when either was given alone or a significant decrease that was never observed when either was given alone. Dopamine or 5-HT also "primed" neurons to respond in an exaggerated manner to the subsequent application of the other monoamine.
Conclusions: These data reveal the unappreciated interactive nature of neuromodulation in cortex by showing that the combined effects of DA and 5-HT can be different from their effects recorded in isolation. On the basis of these findings, we present a theory of how DA and 5-HT might synergistically modulate cortical circuits during various tasks.
Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.