Neurobiology of learning and memory
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Neurobiol Learn Mem · Mar 2010
Late expression of brain-derived neurotrophic factor in the amygdala is required for persistence of fear memory.
In many instances, increase in neuronal activity can induce biphasic secretion of a modulator. The initial release of the modulator triggers the induction of synaptic plasticity, whereas the second-phase release reinforces the efficacy of synaptic transmission and growth of dendrites and axons. In this study, we showed that fear conditioning not only induced the first but also a second peak of brain-derived neurotrophic factor (BDNF) expression. ⋯ The level of growth-associated protein 43 (GAP-43), a marker of newly formed synapses, in the amygdala increased 7 days after fear conditioning. Moreover, conditioned rats had higher AMPA/NMDA ratio than unpaired rats. These results suggest that consolidated memory could be continuously modulated by previous molecular changes produced during memory acquisition.