Amygdala BDNF signaling is required for consolidation but not encoding of extinction

Brain-derived neurotrophic factor ( BDNF) acting through the tyrosine kinase B receptor ( TrkB) is thought to be a critical mediator of learning. As there are no available selective antagonists of TrkB, we used a lentivirus encoding a dominant-negative TrkB ( TrkB.t1) to antagonize BDNF signaling during extinction of conditioned fear. Whereas TrkB. t1-infected rats showed normal within-session extinction, their retention of extinction was impaired, suggesting that amygdala TrkB activation is required for the consolidation of stable extinction memories.