Prelimbic BDNF and TrkB signaling regulates consolidation of both appetitive and aversive emotional learning

The medial prefrontal cortex (mPFC) is known to regulate executive decisions and the expression of emotional memories. More specifically, the prelimbic cortex (PL) of the mPFC is implicated in driving emotional responses via downstream targets including the nucleus accumbens and amygdala, but mechanisms are yet to be fully understood. Therefore, we investigated whether prelimbic cortical brain-derived neurotrophic factor (BDNF) signaling through the high-affinity tyrosine kinase receptor B (TrkB) receptor may serve as a molecular mechanism underlying emotional memory encoding. Here, we utilized viral-mediated inducible bdnf deletion within the PL, as well as TrkB(F616A) mutant mice, wherein TrkB receptor point mutation results in its being highly sensitive to inhibition by small PP1-derivative molecules, serving as a specific TrkB inhibitor. The site-specific TrkB antagonism and viral-mediated bdnf deletion within the PL resulted in deficits in both cocaine-dependent associative learning and fear expression. Deficiencies were rescued by the novel TrkB agonist 7,8-dihydroxyflavone, indicating that PL BDNF expression and downstream signaling through the TrkB receptor are required for memory formation in both appetitive and aversive domains.