Myosin IIB maintains long-term memory

Synaptic plasticity and memory are intrinsically linked to the dynamics of dendritic spines. The protein myosin IIB is central to the morphology and physiology of dendritic spines and thereby regulates synaptic plasticity. In this study, we used specific inhibitors of myosin IIB, blebbistatin (Blebb) and para-nitro-blebbistatin (p-N-Blebb), to assess its role in memory. We found that inhibiting myosin IIB in the hippocampus impairs long-term fear memory consolidation, but not short-term memory, and that pretest blockade hinders memory retrieval. Remarkably, we observed that blocking myosin IIB activity in the hippocampus, amygdala, or insular cortex 24 h after training impairs distinct consolidated memories, suggesting that myosin IIB plays an essential role in memory maintenance. Our results show that myosin IIB activity is crucial not only for memory formation and expression but also for memory storage, likely by preserving dendritic spines after learning.