Profile of variation in potential of higher stable state with change in dopamine releasability W34.

The points shown in asterisks denote the potentials of higher stable states for the respective dopamine releasability, W34 in zone III obtained from the global potential landscape. The solid curve is a fitting to the data. The potential is minimum in the region between the points Q and R of maximum equilibrium excitatory and inhibitory activities, respectively. The point of minima represents the maximum robustness that the circuit dynamics may achieve during the delay period. This further suggests the existence of a subtle ratio of the equilibrium excitatory to inhibitory activity which fine tunes the circuit’s robustness and leads to an inverted-U shaped profile of the robustness of higher stable states during the delay period.