Figure 7.

Schematic drawings of how neurotrophins promote survival of neurons in neonate. A, During the neonatal period when spontaneous network activity is developing, BDNF promotes spontaneous activity while suppressing the apoptosis. B, Molecular mechanism by which neurotrophins exert survival effect via promoting spontaneous activity. Activation of Trk receptor triggers Akt activation that is maintained by spontaneous activity-driven calcium influx through L-type channels. The sustained Akt, which requires signal from integrin β1 signaling, is necessary and sufficient for neurotrophin-dependent survival.