BDNF/trkB signaling in the developmental sculpting of visual connections.

Neurotrophins are a family of secreted molecules that have multiple, profound actions on the structure and function of both developing and mature neurons. Neurotrophins exert their influences by signaling through the trk family of receptor tyrosine kinases and the p75 low affinity neurotrophin receptor. Here we review the contributions of neurotrophins to the development of neural circuitry in the mammalian visual system. We emphasize: (1) the role of neurotrophins as components of the cellular mechanisms by which neuroelectric activity sculpts pattern of brain connectivity; and (2) the results of recent experiments suggesting that the trafficking of neurotrophin proteins may be activity dependent.