Intrinsic membrane properties of pyramidal neurons in vivo. (A) Characteristics of the typical firing patterns in RS (left), IM (middle) and IB (right) evoked by current injections (300 ms, 50 pA step) at resting membrane potentials. These types of neurons exhibited slow afterhyperpolarization (sAHP; ms, mV) with a delayed slow component. Note that the IB neuron has the AP doublet. (B) The population ratios of different neuron groups for RS, IM and IB. (C) Voltage clamp recording at -70 mV. There was no significant difference in the slow oscillations of each type.