Brain-derived neurotrophic factor: a dynamic gatekeeper of neural plasticity.

Brain derived neurotrophic factor (BDNF), a member of the neurotrophin family of structurally related proteins that promote neuronal differentiation and survival during development, is a potent modulator of synaptic plasticity. Changes in BDNF expression, release and neuromodulatory activity, mediated by both epigenetic and post-translational mechanisms, have been associated with many pathological conditions and developmental experiences, such as maternal deprivation and environmental enrichment. Much effort has been devoted to studying plasticity in the hippocampus, a structure traditionally associated with learning and memory, yet there is increasing empirical support for the contribution of another structure--the amygdala--to BDNF-induced changes. Because the amygdala is a critical site for emotional memory formation, and many emotional and neurodevelopmental pathologies have been linked to amygdala-based abnormalities, considerable efforts have been devoted to the characterization of its circuitry. Here we review the role of BDNF as a biochemical integrator of convergent cellular signals, and as a central driver of neural plasticity. We conclude by emphasizing the importance of characterizing BDNF signaling cascades in behaviorally-relevant networks, to identify potential drug targets for novel therapeutic interventions.