Diverse synaptic mechanisms underlying learning and memory consolidation

Memory consolidation is defined as the process by which labile short-term memories are stabilized and transformed into persistent long-term memories. This process relies heavily on synaptic plasticity, particularly long-term potentiation and depression (LTP and LTD, respectively), which have been extensively investigated in previous studies. The advent of optical tools that allow the observation and manipulation of LTP and LTD in vivo has advanced our understanding of their roles in learning and memory consolidation. In addition to LTP and LTD, recent research has indicated the presence of a more rapid plasticity mechanism, termed behavioral timescale synaptic plasticity (BTSP), which is crucial for encoding space and context. Sharp-wave ripples and sleep also play indispensable roles in memory consolidation, with some studies alternately linking them to LTP and LTD. At the systems level, sharp-wave ripples and sleep contribute to the transmission of information to broader brain areas, as well as the modification of synaptic strength in cortical areas for the long-term storage of memory. Furthermore, recent findings have highlighted the role of non-neuronal cells in learning, as they modulate synaptic plasticity in various ways. • In vivo inhibition of plasticity evidences synaptic memory consolidation mechanisms. • Structural long-term potentiation (sLTP) is indispensable for memory consolidation. • Informative/less informative synapses are up/downregulated during sleep. • Behavioral Timescale Synaptic Plasticity (BTSP) underlies place cell formation. • Non-neuronal cells play critical roles in synaptic plasticity and memory formation.