Electrophysiological parameters of fast-spiking (FS) and regular-spiking (RS) neurons.
Analysis was done on a subset of 32 FS interneurons and 25 RS cells in slices from 25 and 22 animals, respectively, 3–6.5 weeks old (14 animals were common to both subsets). A total of eight electrophysiological parameters were analyzed per cell. Single-spike parameters were measured at rheobase (minimal current evoking an action potential). All current steps were 600 ms long.
Electrophysiological parameters definitions:
Vrest: resting potential upon break-in, with no holding current applied.
Vthreshold: the voltage where dv/dt = 5 V/s.
Spike height: Spike peak-Vthreshold.
Spike width at half-height (SWHH): spike width measured half-way between Vthreshold and spike peak.
After Hyperpolarization (AHP): Vthreshold -spike trough.
Input Resistance (Rin): the slope of the I-V plot, calculated from 4 to 6 positive and negative subthreshold current steps, at membrane potentials up to ±15 mV from rest.
Imax: the maximal current step applied before a noticeable reduction in spike height.
Fmax: the maximal steady-state firing frequency, computed as the reciprocal of the average of the last five interspike intervals (ISIs) in a spike train elicited by Imax.