Cellular and molecular mechanisms of dendrite growth

Proper growth and branching of dendrites are crucial for nervous system fun ction; patterns of dendritic arborization determine the nature and amount o f innervation that a neuron receives and specific dendritic membrane proper ties define its computational capabilities. Until recently, there was relat ively little known about the cellular and molecular mechanisms of dendritic growth, perhaps because dendrites were historically considered to he intri nsically determined, passive elements in the formation of connections in th e nervous system. In the last few years, however, overwhelming evidence has accumulated indicating that dendritic growth is remarkably dynamic and res ponsive to environmental signals, including guidance molecules and levels a nd patterns of activity. This manuscript reviews our current understanding of the cellular and molecular mechanisms of dendritic growth, the influence of activity in sculpting specific patterns of dendritic arbors, and a pote ntial integral role for dendrites in activity-dependent development of circ uits in the nervous system.