Summary: Researchers have identified the in vivo synapse dynamics that underlie fear memory formation and extinction in the living brain.
Source: Seoul National University
Sets of synaptic networks are known to underlie cognitive functions, and connections between engram neurons are enhanced during memory formation.
A study by researchers led by Professor Bong-Kiun Kaang and Professor Hye Yoon Park, identified the live dynamics of the synapses that underlie the formation and extinction of fear memory in living brains.
Researchers have enabled the observation of identical synapses at multiple points in time by adapting longitudinal two-photon imaging to the dual eGRASP system for the first time.
Synapses between engram cells specifically underwent synaptogenesis during memory formation, while memory extinction led to their correlated demise.
In addition, the particular formation of new synapses resulted in the clustering of synaptic engrams.
Professor Kaang said: “We have shown for the first time how synaptic engrams change in identical individuals according to different memory states.
“This adaptation of the dual-eGRASP system will open the possibility for longitudinal observation of diverse synaptic networks.
“We also hope that our findings will provide a basis for advanced understanding of engram networks,” Prof Kaang said.
About this memory research news
Author: Kwang Hyun Yang
Source: Seoul National University
Contact: Kwanghyun Yang – Seoul National University
Picture: Image is in public domain
Original research: Free access.
“Hippocampal engram networks for fear memory recruit new synapses and modify pre-existing synapses in vivo” by Bong-Kiun Kaang et al. Current biology
Abstract
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Hippocampal engram networks for fear memory recruit new synapses and modify pre-existing synapses in vivo
As the basic units of neural networks, sets of synapses underlie cognitive functions such as learning and memory. These synaptic engrams show high synaptic density among engram cells as a result of contextual fear memory formation. Subsequent analysis of the CA3-CA1 engram synapse revealed larger spine sizes, as synaptic connectivity correlated with memory strength.
Here, we elucidate the synapse dynamics between CA3 and CA1 by tracking identical synapses at multiple time points by adapting two-photon microscopy and the dual-eGRASP technique. live.
After memory formation, synaptic connections between engram populations are enhanced in conjunction with synaptogenesis within the hippocampal network.
However, extinction learning was specifically correlated with the disappearance of the CA3 engram at the synapses of the CA1 engram (EE).
We observed “newly formed” synapses near pre-existing synapses, which clustered CA3-CA1 engram synapses after fear memory formation. Overall, we conclude that the dynamics of the CA3 to CA1 EE synapses are key sites of modification during fear memory states.