Fig. 1From: How Adaptation Makes Low Firing Rates RobustSolutions of Eqs. (1), (2). \(I = 1\) and z fixed at 0 (A and B) or 0.7 (C and D). Time courses shown in (A and C). In the phase planes (B and C) the blue curves are the x nullclines, red curves are y nullclines, black curves are the trajectories, labeled with slow (single arrow) and fast (double arrow) segments. Increasing z narrows the gap between the left branches of the x and y nullclines, increasing the period by prolonging the interspike intervalBack to article page