Fig. 10

The left panel shows the E–I phase plane and nullclines of Eq. (7). The intersections of the two null clines are equilibrium or fixed points of the equations. Those labeled (+) are stable, those labeled (−) are unstable. Parameters: \(w_{EE}=12\), \(w_{EI}=4\), \(w_{IE}=13\), \(w_{II}=11\), \(n_{H} = 0\). The stable fixed points are nodes. The right panel shows an equilibrium which is periodic in time. Parameters: \(w_{EE}=16\), \(w_{EI}=12\), \(w_{IE}=15\), \(w_{II}=3\), \(n_{H}=1.25\). In this case the equilibrium is a limit cycle. [Redrawn from [24]]