Figure 4.

Transition from a synchronized rhythmic firing state to a winner-take-all bump spiking activity–(G). In this simplified surround inhibition network, short-term synaptic plasticity (STSP) and NMDA gating effects are removed, GABAb conductance is set to be zero and individual excitatory and inhibitory spiking models are changed to have the same biological parameter set. First row shows the 1-s spatial-temporal evolutions of individual conductance for AMPA–(A), NMDA–(B), and GABAa–(C). Second row (D–F) show the averaged conductance over time for excitatory and inhibitory cells separately. Notice that bump activity in AMPA and NMDA conductance appear in inhibitory neurons first (see A,B), while both conductances are spatially uniform even after spiking bump activity emerged after about 400 ms. The fact that spatial uniformity is destroyed in GABAa conductance first in (C) suggests that inhibitory neurons might show transition into winner-take-all state early and then bias the transition in excitatory cells.