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Arousal from hibernation alters contextual learning and memory.
Maegan M Weltzin1, Huiwen W Zhao, Kelly L Drew
1Alaskan Basic Neuroscience Program, Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775-7000, USA.
Behavioural Brain Research
|October 13, 2005
Summary
Hibernation causes significant changes in brain structure. Arctic ground squirrels show enhanced memory 24 hours after arousal, suggesting a link between synaptic remodeling and cognitive function.
Area of Science:
- Neuroscience
- Physiology
- Animal Behavior
Background:
- Hibernation involves reversible decreases in body temperature and metabolism.
- Hippocampal synapses undergo significant structural changes during hibernation and arousal.
- These structural changes include alterations in dendritic branches and spine densities.
Purpose of the Study:
- To investigate the functional consequences of hibernation-induced synaptic structural changes.
- To assess the impact of these changes on hippocampal-dependent learning and memory.
Main Methods:
- Wild-caught Arctic ground squirrels were trained in a contextual fear conditioning task.
- Training and testing occurred at specific time points after arousal from hibernation (3h, 24h, 4 weeks).
- Behavioral responses were assessed during a fear memory retention test.
Main Results:
- All groups acquired the fear response similarly during training.
- Squirrels tested 24 hours after arousal showed enhanced contextual fear expression.
- This enhancement was significantly greater than in groups tested at 3 hours or 4 weeks post-arousal.
Conclusions:
- Morphological and biochemical changes in the hippocampus 24 hours post-arousal impact learning and memory.
- Hibernation provides a unique model to study neural substrates of cognitive enhancement.
- Synaptic remodeling during hibernation may underlie temporary cognitive improvements.