Conventional measures of intrinsic excitability are poor estimators of neuronal activity under realistic synaptic inputs
Fig 6
Manipulations of the voltage dependence and kinetics of the K-currents exert profound effects on the firing responses of the model neurons.
(A) The half-voltage of the steady-state activation curve (Vm,1/2) of the Kir-current is shifted from -91 to -75 mV and the cumulative spike counts of 25 model instances are calculated. Black arrows indicate the model responses shown in A1 and A2. (B) The peak activation time constant of the Kir-current (τm,max) is shifted from 10 to 130 ms and the cumulative spike counts of the corresponding model responses are plotted. (C) Similar manipulation is performed on the steady-state activation midpoint of the D-current of the stuttering type model (25 instances). (D) Peak activation time constant of the D-current is shifted from 2 to 18 ms. Here, models featuring the ‘fast’ D-current exhibit high static and low dynamic excitability, while those with the ‘slow’ D-current exhibit low static spike counts and high dynamic spike counts.