To investigate excitatory postsynaptic potentials (EPSPs), intracellular recordings were performed in layer II/III neurons of the rat medial frontal cortex. The average resting membrane potential of the neurons was more than -75 mV and their average input resistance was >20 MΩ. The amplitudes of the action potentials evoked by injection of depolarizing current pulses were >100 mV. The electrophysiological properties of the neurons recorded were similar to those of regular-spiking pyramidal cells.
