Effects of dopaminergic modulation of persistent sodium currents on the excitability of prefrontal cortical neurons: A computational study

Yang and Seamans (J. Neurosci. 16 (5) (1996) 1922-1935) have recently shown that pyramidal cells in rat prefrontal cortex respond to a brief current i njection with a plateau potential that is mediated by slowly inactivating v oltage-dependent sodium currents. They also report that dopamine receptor a ctivation increases plateau duration and shifts its activation to more nega tive potentials. We model persistent sodium currents by including an additi onal slow inactivation parameter in the standard spike-generating sodium ch annel model. Our model reproduces the voltage plateau and the dopamine-indu ced increase in plateau duration. We extend the model by including a set of potassium currents and examine the effect of dopaminergic modulation of so dium current on neuronal excitability. We find that dopamine increases the gain of the current to firing frequency relationship. However, modulation o f sodium current has minimal effects on the amplitude of subthreshold EPSPs . (C) 1999 Published by Elsevier Science B.V. All rights reserved.