Choi, J. H., Sim, S. E., Kim, J. I., Choi, D. I., Oh, J., Ye, S., … & Kaang, B. K.
(2018). Interregional synaptic maps among engram cells underlie memory formation. Science,
360(6387), 430-435. https://science.sciencemag.org/content/360/6387/430.abstract
Engram cell tagging and dual-eGRASP
Hippocampus CA3 -> CA1
CA3 and CA1 hippocampal engram cells associated with a contextual fear memory
were tagged (Fos promoter-driven rtTA delivered by AAV) and made to express eGRASP
proteins to identify CA3 engram cell -> CA1 engram cell synapses (yellow synapses on red
dendrites). Subset of non-engram synapses were also labeled with different colors as control.
Engram-to-engram synapse numbers were elevated relative to control non-engram synapses
and their spines were larger. This supports the theory that a memory engram is ‘stored’ as
increases synaptic connectivity between engram cells.
“The relationship between memory strength and synaptic connectivity suggests that
these specific connections between engram cells across two directly connected brain regions
form the synaptic substrate for memory.”
BPF Journal Club
