Engram Synapses and Synapse Dynamics in Memory Processing

Synaptic plasticity is believed to underlie a range of cognitive functions, including learning and memory. Numerous studies have shown that memory formation not only modifies the strength of existing synapses but also alters the dynamics of synaptic turnover. The dynamics of the synaptic landscape reflect brain-wide genetic changes and the activation of molecular mechanisms that mediate pre- and postsynaptic structural plasticity. The activity-dependent nature of these mechanisms leads to an intriguing possibility that synapses between engram neurons across multiple brain regions, or "engram synapses," may act as a hub for such synaptic changes. This review aimed to highlight the close relationship between the dynamics of synapse turnover and memory storage and summarize the underlying molecular mechanisms involved. The analysis highlights the need for more systematic investigation into how engram-specific synapses form and are eliminated across different brain regions.