Figure 4.

4-AP induced activity propagates at a similar speed in all four directions. A, Left, An example of the speed analysis, which was based on the timing of the peaks of the spontaneous spiking. Recordings obtained from 6 different channels in one row of the microelectrode array. The dashed box represents the peaks from the first and last channel in the same time window. Right, Cross-correlation was applied to the peaks in the time window to determine the time delay. B, Speed histograms of the spontaneous activity induced by 4-AP. The speed was calculated in both longitudinal and transverse axes bidirectionally, giving four propagation directions (also see Fig. 2A): septal-to-temporal (S to T), temporal-to-septal (T to S), CA3-to-CA1 and CA3-to-DG (within CA3, along the direction from CA3 to DG).