Coincident Pre- and Post-Synaptic Cortical Remodelling Disengages Episodic Memory from Its Original Context
The view that the neocortex is remotely recruited for long-term episodic memory recall is challenged by data showing that an intense transcriptional and synaptic activity is detected in this region immediately after training. By measuring markers of synaptic activity at recent and remote time points from contextual fear conditioning (CFC), we could show that pre-synaptic changes are selectively detected 1 day post-training when the memory is anchored to the training context. Differently, pre- and post-synaptic changes are detected 14 days post-training when the memory generalizes to other contexts. Confirming that coincident pre- and post-synaptic remodelling mediates the disengagement of memory from its original context, DREADDs-mediated enhancement of cortical neuron activity during CFC training anticipates expression of a schematic memory and observation of bilateral synaptic remodelling. Together, our data show that the plastic properties of cortical synapses vary over time and specialise in relation to the quality of memory.
KeywordsSystems consolidation Episodic memory Neocortex Synaptic proteins Miniature EPSC Dendritic spines DREADDs
These authors equally contributed to this work. GV, MAT and AP designed the experiments. GV and AB run behavioural, western blot/immunohistochemistry, and morphological experiments. SM and MG performed electrophysiological experiments. AP and GC carried out DREADDs experiments. MAT wrote the manuscript.
This work was financially supported by a grant (AGESPAN) from CNR-National Research Council of Italy.
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