Fig. 1.

Development of synapses and spine motility in organotypic hippocampal slices. (A Left) Example traces from slices prepared at p6 and cultured as indicated showing mEPSCs recorded in the presence of 1 μM TTX and 100 μM PTX at −60 mV. (Scale bar, 20 pA and 1.3 s.) (Right) Example of apical dendritic spines from neurons transfected with GFP in slices as indicated. (Scale bar, 5 μm.) (B) Cumulative fraction of all IEIs of mEPSCs from slices cultured for 4–5 (n = 12), 7–8 (n = 27), or 11–12 (n = 9) days. Frequency of mEPSC increases significantly from 4–5 dic to 7–8 dic (KS test D = 0.3053, P < 0.01). A smaller but still significant increase occurs at 11–12 dic (KS test D = 0.0536, P < 0.01). (Inset) IEI cell average. Error bars represent SEM. *P < 0.05, Student's t test. (C) Quantification of dendritic spine density from cells from slices 4–5 dic (n = 9), 7–8 dic (n = 8), and 11–12 dic (n = 14). (D) Total spine motility decreases with age. Quantification of all spine motility events (filopodia extension + new spine emergences + spine retraction) per micrometer from cells transfected with GFP from slices 4–5 dic (n = 8), 7–8 (n = 8), and 11–12 dic (n = 6). Confocal live images were taken at intervals of 10 min for 2 h. (E–G) Quantification of filopodia extension (E) and new spines appearing per micrometer of dendrite (F), and percentage of spines retracting (G) from cells, as in D.