Figure 6.

Bifurcation diagram of the finely tuned parametric working memory model, as a function of applied synaptic drive conductance, g_App. Synaptic drive is an offest conductance for demonstration purposes, that we add to the positively montonic neurons and subtract from the excitatory input to negatively monotonic neurons. A negative drive means the positively monotonic neurons have reduced synaptic excitation. A shift in any intrinsic neuronal parameter has a similar effect on the system. All the stable states are computed using the mean field theory for the entire network of twelve positively monotonic and twelve negatively monotonic, excitatory and inhibitory, neural groups. These persistent states are plotted as the firing rates of cells in neural group 3. (A) A quasi-continuum of stable firing rates is possible with correct tuning of applied synaptic drive. (B) An enlargement of the region near the quasi-continuous attractor indicates a discrete number of stable persistent states close to the number of neural groups, with small changes in firing rate between states. Portions of the curve with negative slopes are the branches of unstable states (dashed lines).