Fig. 4.
Spike-frequency adaptation reduces responses to stimuli with low derivatives without much effect on high derivative stimuli. a Instantaneous frequency and calcium response of the model with gCa = 1 mS/cm2 for various current ramp slopes. All steps were from 0 to 20 nA. The ramp slope was varied by modulating current injection duration. The black response is to an instantaneous step to 20 nA. Injected current is depicted below. b Instantaneous frequency and calcium response of the model with gCa = 1 mS/cm2 for various baseline currents and steps 50 ms long to 10 nA above baseline (slope of 0.2 nA/ms; Ibase of 0, 2, 6, and 10 nA). c–e Maximal change in firing frequency (Δfmax−base) for various baseline currents (Ibase; gray scale, as indicated in panel d) and current ramp slopes. All steps were 10 nA in amplitude at their maximum. The three panels show the response of the model with varying degrees of spike-frequency adaptation: none (gCa = 0 mS/cm2; c), fit to the underlying physiology (gCa = 1 mS/cm2; d), and above the physiological-fit value (gCa = 2 mS/cm2; e). The gray line denotes the response with Ibase = 0 nA and gCa = 1 mS/cm2. The inset in panel e shows response variability (〈σΔf〉; see Fig. 2) as a function of gCa