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Protocol for Studying Extinction of Conditioned Fear in Naturally Cycling Female Rats
Published on: February 23, 2015
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Reduction in Reward-Driven Behavior Depends on the Basolateral But Not Central Nucleus of the Amygdala in Female Rats
Belinda P P Lay1, Guillem R Esber1, Mihaela D Iordanova2
1Center for Studies in Behavioural Neurobiology, Department of Psychology, Concordia University, Montreal, Quebec H4B 1R6, Canada.
Summary
Neural mechanisms of memory extinction differ between sexes. In female rats, the central nucleus of the amygdala does not regulate extinction retrieval, but the basolateral amygdala plays a key role.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Memory Research
Background:
- Adaptive behavior relies on balancing memory acquisition and extinction.
- Rodent studies reveal sex-based differences in extinction learning rates.
- Previous research implicated central nucleus (CN) of the amygdala neurons in male extinction retrieval.
Purpose of the Study:
- To investigate if the CN mechanism for extinction retrieval observed in males also applies to females.
- To explore potential sex-based differences in amygdala involvement in extinction.
- To understand the neural basis of sex differences in adaptive behavior.
Main Methods:
- Deletion of extinction-recruited neurons in the central nucleus (CN) of the amygdala in female rats.
- Assessment of extinction retrieval after single or extended extinction training.
- Measurement of neuronal activation in the CN and basolateral amygdala (BLA) during extinction.
- Targeted ablation of basolateral amygdala (BLA) neuronal ensembles in females during early extinction.
Main Results:
- Deleting extinction-recruited CN neurons did not affect extinction retrieval in female rats.
- Females exhibited greater BLA activation than males during early extinction.
- Ablation of the BLA ensemble in females during early extinction significantly reduced conditioned approach.
- CN activation during extinction did not differ between sexes.
Conclusions:
- The neural mechanism involving CN neurons for extinction retrieval in males is not conserved in females.
- Heightened BLA activation in females during early extinction may inhibit the emergence of extinction-like behavior.
- A potential interplay between the CN and BLA regulates conditioned approach in females.
- Findings suggest sex-specific neural strategies for memory extinction, informing sex-based therapeutic approaches for cue-triggered behaviors.
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