Two modes of activity-dependent synaptogenesis of cerebral neurons in vitro.

Effects of transduction activity and transmission activity on synaptogenesis of chick cerebral neurones in dissociated cell culture were studied electrophysiologically using two blockers for these activities, tetrodotoxin (TTX) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), respectively. CNQX inhibited the increase of evoked EPSCs more effectively than TTX, whereas both blockers similarly reduced the increase of miniature EPSCs (Minis). These data indicated that not only transduction-dependent transmission activity but also transduction-independent spontaneous activity regulate the synaptic efficiency. These two activities are suggested to change the quantal amplitude and the number of synaptic sites, respectively.