Figure 3.

The intrinsic parameters can determine the fate of the follower neuron trajectory. Two qualitatively distinct cases are shown in the phase space based on the shape and relative position of the nullclines which are in turn determined by the relative positions of w_∞(v) and MB. (a) and (b) show these two cases in the v-w phase plane while (c) and (d) show them in the w-h phase plane respectively. In the w-h phase plane, the curves LK, FP and UK correspond to the lower knee LK, the upper knee UK and the fixed point FP in the v-w phase plane. The point “Start” denotes the entrance of the trajectory into the w-h phase plane and the grey area represents the potential paths of the trajectory. (a) In the v-w phase plane, the two nullclines intersect at FP on MB. (b) In the v-w phase plane, there is no intersection on the middle branch of the v-nullcline. (c) In the w-h phase plane, the trajectory is blocked by FP and can never reach UK. (d) In the w-h phase plane, the trajectory may reach UK since there is no FP.