A synapse-specific refractory period for plasticity at individual dendritic spines

• 成果类型: Article
• 署名作者: Flores, Juan C.; Sarkar, Dipannita; Zito, Karen
• 署名单位: University of California System; University of California Davis
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10387
• DOI: 10.1073/pnas.2410433122
• 发表日期: 2025-01-14
• 关键词: long-term potentiation; postsynaptic density; nmda receptors; psd-95; memory; experience; STABILITY; nascent; ltp; stabilization

摘要

How newly formed memories are preserved while brain plasticity is ongoing has been a source of debate. One idea is that synapses which experienced recent plasticity become resistant to further plasticity, a type of metaplasticity often referred to as saturation. Here, we probe the local dendritic mechanisms that limit plasticity at recently potentiated synapses. We show that recently potentiated individual synapses exhibit a synapse- specific refractory period for further potentiation. We further found that the refractory period is associated with reduced postsynaptic CaMKII signaling; however, stronger synaptic activation fully restored CaMKII signaling but only partially restored the ability for further plasticity. Importantly, the refractory period is released after one hour, a timing that coincides with the enrichment of several postsynaptic proteins to preplasticity levels. Notably, increasing the level of the postsynaptic scaffolding protein, PSD95, but not of PSD93, overcomes the refractory period. Our results support a model in which potentiation at a single synapse is sufficient to initiate a synapse- specific refractory period that persists until key postsynaptic proteins regain their steady- state synaptic levels.