Figure 1

MAP2 staining of dendrites and somata: control networks (A) display characteristic features of an activity-dependent wiring process including fasciculation and ramification of dendrites within clusters. Developmental inhibition of PKC (B) generates more homogeneous networks in which neurites grow out ignoring neuronal neighbors. Propagation of activity in spontaneous and stimulation-induced bursts was analyzed in micro-electrode recordings (first spike rank order from light to dark gray; black: no activity; white circles indicate stimulation sites): bursts in control networks (C) display irregularities in the spatial propagation pattern indicating complex underlying structure. Homogeneous networks developing under impaired PKC activity (D) show highly isotropic propagation patterns. Spontaneous (E) and elicited (F) propagation patterns in controls are hardly comparable. Stimulation of homogeneous networks elicits highly isotropic propagation patterns (H) similar to those in spontaneous bursts (G). Scale bars: 2mm.