Form follows function: BDNF and its involvement in sculpting the function and structure of synapses.

Neurotrophins are essential for multiple aspects of neuronal development and function. Especially BDNF (brain-derived-neurotrophic-factor) has been shown to play an important role in neuronal survival and in the maintenance of several neuronal systems. In addition, BDNF has been implicated in numerous processes of functional and structural synaptic plasticity. In this review we would like to summarize what is known regarding the cellular mechanism mediating the activity of BDNF during functional and/or structural changes at neurons in order to promote synaptic plasticity. In addition, we address open questions and conflicting results. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.