(IMAGE)
Caption
Dynamic mechanisms of engram maturation. During the allocation, engram allocation is primarily governed by enhancements in intrinsic neuronal excitability, driven primarily by increased phosphorylation of CREB, which primes these cells for selective recruitment. Following allocation, engram formation is molecularly marked by the expression of IEGs including Fos, Npas4, Arc, and Egr1. The consolidation phase is characterized by epigenetic reprogramming, such as DNA methylation, histone posttranslational modifications (e.g., acetylation, phosphorylation), and histone variant exchange. Concurrently, neuronal excitability is further modulated through synaptic recruitment of NMDA receptors, AMPA receptors, and inwardly rectifying potassium channels (Kir), while dendritic spine density increases to reinforce synaptic connectivity. Throughout this maturation process, engrams transition from a silent state to a functionally mature configuration, marked by enduring structural and molecular adaptations that support long-term memory storage.
Credit
Zhe-Yu Chen
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CC BY-NC-ND