The Persistent activity propagates in both the deep and superficial layers of the cortex
Figure 7. During preparation of the cortical slice, the deep layers (layers 4-6) of the cortex were cut with a knife. Still, the slow oscillation propagated from layer 5 on the left side of the cut to layer 5 on the right. The cross-correlogram on the right illustrates the synchronized activity before (gray) and after (red) the local application of the glutamate receptor antagonist CNQX to the superficial layers (2/3). The local block of excitatory neurotransmission blocks the propagation of the slow oscillation.