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Competition between engrams influences fear memory formation and recall.
Asim J Rashid1, Chen Yan1, Valentina Mercaldo1
1Program in Neurosciences and Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada. Department of Psychology, University of Toronto, Toronto, ON M5G 3G3, Canada. Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada. Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada.
Science (New York, N.Y.)
|July 28, 2016
Summary
Cellular engrams represent memories. This study reveals a transient competition in the lateral amygdala that integrates or separates memories based on timing, influencing how neuronal populations form engrams.
Area of Science:
- Neuroscience
- Memory Research
- Cellular Biology
Background:
- Engrams, collections of cells, are the biological basis of memory.
- Previous research focused on single engrams, leaving interactions between multiple engrams unclear.
- In the lateral amygdala (LA), neuronal excitability influences engram formation.
Purpose of the Study:
- To investigate if neuronal excitability governs interactions between multiple memory engrams.
- To understand how temporal intervals between learning events affect engram formation and memory consolidation.
- To explore the competitive dynamics underlying the allocation of neurons to distinct engrams.
Main Methods:
- Mice underwent two fear conditioning events with varying time intervals.
- Optogenetic manipulation of neuronal excitability in the lateral amygdala (LA).
- Analysis of neuronal population allocation to fear memory engrams.
Main Results:
- A transient competitive process was identified in the LA.
- Memories of closely timed events were integrated via overlapping neuronal populations in engrams.
- Memories of distally timed events were separated by non-overlapping neuronal populations.
Conclusions:
- Neuronal excitability drives a competitive mechanism for engram formation.
- This competition dynamically integrates or separates memories based on their temporal proximity.
- The findings provide insights into the neural mechanisms of memory interaction and consolidation.
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