Neocortical synaptic engrams for remote contextual memories.
Ji-Hye Lee1, Woong Bin Kim1, Eui Ho Park1
1Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA.
Nature Neuroscience
|December 23, 2022
Summary
Remote contextual memories strengthen through persistent synaptic changes in the prefrontal cortex (PFC). This CREB-dependent plasticity, involving PFC engram neurons, is crucial for long-term memory storage.
Area of Science:
- Neuroscience
- Memory Consolidation
- Synaptic Plasticity
Background:
- Initial memory encoding relies on hippocampal circuits.
- Long-term memory storage shifts to the neocortex, becoming less hippocampus-dependent.
- The precise synaptic mechanisms for remote memory storage remain unclear.
Purpose of the Study:
- To investigate the synaptic substrates of remote contextual fear memories.
- To elucidate the role of prefrontal cortex (PFC) circuits in long-term memory consolidation.
Main Methods:
- Studied remote contextual fear memories in mice.
- Examined synaptic plasticity of prefrontal cortex (PFC) engram neurons.
- Investigated the involvement of CREB and hippocampal signals.
Main Results:
- Consolidation of remote memories correlated with strengthened excitatory connections in PFC engram neurons.
- Memory extinction weakened these specific synapses.
- Synapse-specific plasticity was CREB-dependent and required hippocampal signals conveyed via retrosplenial cortex to PFC.
Conclusions:
- Progressive, synapse-specific strengthening of PFC circuits supports long-term contextual memory storage.
- PFC engram neurons form robust connections with other recruited PFC neurons for remote memory recall.
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