Molecular mechanisms mediating engram ensemble retrievability state in mice

Area of Science:

• Neuroscience
• Molecular Biology
• Memory Research

Background:

• Memory engrams, neural ensembles storing memories, vary in retrievability.
• Silent engrams are unresponsive to sensory cues but can be reactivated by direct stimulation.
• Forgetful TgCRND8 mice exhibit enhanced endocytosis of GluA2-containing AMPA receptors, leading to silent engrams.

Purpose of the Study:

• Investigate molecular mechanisms of engram silencing and un-silencing.
• Determine the role of GluA2 trafficking in memory retrievability.
• Explore strategies for restoring inaccessible memories.

Main Methods:

• Utilized forgetful TgCRND8 mice and wild-type mice.
• Employed optogenetic activation to study engram retrieval.
• Manipulated GluA2 receptor endocytosis and trafficking.

Main Results:

• Blocking GluA2 endocytosis in Tg mice restored memory retrieval by increasing synaptic GluA2 content.
• Induced silent engrams in wild-type mice via LTD-type stimulation.
• Demonstrated that disrupting GluA2 removal could un-silence these induced silent engrams.

Conclusions:

• GluA2 receptor trafficking is a critical regulator of engram retrievability.
• Targeting GluA2 removal presents a potential strategy for memory restoration.
• Findings offer insights into mechanisms underlying memory loss and retrieval.