Distribution of electrophysiological properties.

(A) Illustration of how a subset of the parameters were measured from the action potential shape of the first action potential in response to somatic current injection: threshold voltage (Vth), width at threshold (WAP,thresh), width at half-max (WAP), height, maximum fall rate (Min(dV/dt)), and afterhyperpolarization latency (LAHP). (B) Distribution of the measured values for the 14 electrophysiological parameters from membrane potential recordings in response to somatic current injection from 225 pyramidal neurons: rheobase current (Ir), membrane time constant (tm), action potential voltage threshold (Vth), action potential frequency adaptation ratio (AP FAR), action potential amplitude (AP Height), action potential duration at threshold (WAP,thresh), action potential fall rate (Min(dV/dt)), time to peak of the afterhyperpolarization (LAHP), action potential duration halfway between threshold and peak (WAP), action potential duration increase (WAP Inc.), resting membrane potential (Vrest), action potential amplitude decrement (Vpeak Dec.), input resistance (IR), interspike interval variability (ISI Var). The apparent deviations from normal distributions suggest that there are discrete groups of pyramidal neurons within this population.