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Route-dependent spatial engram tagging in mouse dentate gyrus
Lucius K Wilmerding1, Ivan Kondratyev2, Steve Ramirez1
1Center for Systems Neuroscience, Boston University, United States; Graduate Program for Neuroscience, Boston University, United States; Department of Psychological and Brain Sciences, Boston University, United States.
Neurobiology of Learning and Memory
|February 23, 2023
Summary
The dentate gyrus (DG) separates similar spatial memories. Different routes within an environment are encoded by distinct DG cell ensembles, supporting navigation memory.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Memory Research
Background:
- The dentate gyrus (DG) is theorized to function as a pattern separator.
- Sparse neuronal ensembles (engrams) in the DG are linked to memory formation and retrieval.
- DG cell activity shows spatial specificity and stability during navigation.
Purpose of the Study:
- To investigate how the DG distinguishes between global context and individual navigational routes.
- To examine DG engram reactivation patterns when mice navigate familiar and altered environments.
Main Methods:
- Mice performed a delayed-non-match-to-position (DNMP) T-maze task.
- DG neurons were labeled during task performance.
- Engram reactivation was assessed after mice navigated different environments the next day.
Main Results:
- Engram reactivation varied based on maze route traversal.
- Traversing one arm resulted in higher-than-chance but lower-than-full-task ensemble overlap.
- Mice in an open field showed chance-level engram reactivation.
- Behavioral variability did not explain engram overlap differences.
Conclusions:
- The DG contributes to spatial navigation memory.
- Partially non-overlapping DG ensembles encode distinct routes within a spatial context.
