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 injection with a plateau potential that is mediated by slowly inactivating voltage-dependent sodium currents. They also report that dopamine receptor activation increases plateau duration and shifts its activation to more negative potentials. We model persistent sodium currents by including an additional slow inactivation parameter in the standard spike-generating sodium channel model. Our model reproduces the voltage plateau and the dopamine-induced increase in plateau duration. We extend the model by including a set of potassium currents and examine the effect of dopaminergic modulation of sodium current on neuronal excitability. We find that dopamine increases the gain of the current to firing frequency relationship. However, modulation of sodium current has minimal effects on the amplitude of subthreshold EPSPs. (C) 1999 Published by Elsevier Science B.V. All rights reserved.