Figure 5.

The periodic solutions in Case 1 when the A-current is moderate (a) or strong (b). (a) Left panel: a modest A-current causes a phase delay to the active state. Middle panel: the periodic solutions in the v-w phase plane. Right panel: The trajectory in the w-h phase plane, which shows the dynamics on the middle branch. The trajectory reaches the curve of the lower knee (LK) during T_in, therefore the membrane potential reaches the active state after a phase delay. (b) Left panel: the follower neuron cannot reach the active state when the A-current is strong. Middle panel: the periodic solutions in the v-w phase plane. The trajectory jumps back to the left branch when the inhibition starts. Right panel: The trajectory reaches the curve of the fixed point (FP), and then it moves downward along FP. It does not reach LK during T_in, therefore the membrane potential does not reach the active state. The arrows in the left and middle panels denote the inactive (black), active (red) and intermediate (blue) states. The labels [1–4] in the middle panels denote the v-nullcline corresponding to the times denoted by the same label in the left panel.