[Molecular basis of long-lasting synaptic modifications underlying learning and memory].

Neurons make contact with each other and form neuronal networks. The synapse, the site of contact between 2 neurons, has the ability to dynamically modify functional efficiency and connectivity in response to spatially and temporally specific patterns of neuronal activity. Such plastic ability of the synapse is believed to be indispensable for our cognitive functions, including learning and memory. In this review, I summarize our current understanding of the molecular and cellular mechanisms underlying synaptic plasticity. Lines of evidence have indicated that postsynaptic regulations of AMPA-type glutamate receptors (AMPA-Rs) are crucial for synaptic plasticity. Synaptic plasticity can be long-lasting if the local synaptic modifications interact with activity-dependent, newly synthesized plasticity-related molecules in the neuronal cell body. Recently, we found that the activity-regulated memory-related protein Arc is involved in synapse-specific regulation of AMPA-Rs. This Arc-dependent mechanism, together with other molecular mechanisms, possibly helps maintain the contrast of synaptic strength between strong and weak synapses, thus, promoting the formation of long-term memory.