Volume 50 Issue 3: May 4 , 2006

Next Issue:  May 18

Silent synapses are frequently found in the developing brain. Using paired patch-clamp recordings from cultured hippocampal neurons at an early development stage, Shen et al. identified nonfunctional contacts that lack both AMPA- and NMDA-mediated synaptic responses and are thus different from the conventional silent synapses containing NMDA-only responses. The authors show that presynaptic theta burst stimulation rapidly converts these contacts into functional synapses due to enhanced presynaptic glutamate release and actin polymerization induced by activation of BDNF-Cdc42 signaling at presynaptic release sites. These findings reveal a novel mechanism underlying activity-induced rapid presynaptic maturation during a critical stage of synapse formation. The context and implications of this study are discussed in a Preview by Atasoy and Kavalali.