Figure 3

Spike raster plots (SRPs), mean activity levels and kappa values. Examples of SRPs and corresponding kappa values illustrate the temporal and spatial development of spikes detected by electrodes (vertical axis) over a time period of 60 seconds (horizontal axis) in different cultures (a, b) and different time points after the removal of FGF2. The effect of 50 μM bicuculline is illustrated in right panels of a, vi and b, iii. Mean activity levels (spikes/minute) and the degree of synchronous bursting (kappa values) at 28 div are illustrated for different cultures (c, i + ii). The development of mean activity levels and synchronous bursting between 14 and 28 div is given as ratios (c, iii + iv).