Figure 1.

Spontaneous network activity development of lateral cortex cultures (vCtx). (A) The total spike frequency is shown over time for the same culture at different stages of development (DIV, see labeling on the left side). vCtx cultures develop a heterogeneous pattern of burst discharges when maintained several weeks in vitro. The upper part of each graph indicates the global firing rate, which is defined as the number of detected spikes through all MEA electrodes per time unit (second). Spikes detected by individual electrodes are indicated by gray levels in the lower part. The same scale (see gray scale at 13 DIV) was used for all graphs. Each of the vertically stacked horizontal lines corresponds to one electrode. For clarity only 5 min out of the 20-min recording sessions are shown. Arrows indicate bursts which are shown in higher temporal resolution in (B). (B) Individual population bursts in higher time resolution. Lower case letters correspond to labeling in (A). Dotted lines indicate detected burst limits. Time unit for the global firing rate is 0.1 s. (C) Histograms of the interburst interval (top) and electrode attendance in bursts (bottom) for a 20-min recording session for the culture shown in (A) at 13 DIV. Note the log scale for the interburst interval histogram (bin size is 1 s). (D) Same as (C) except for 17 DIV. (E) Same as (C) except for 22 DIV.