Fear Conditioning and Extinction
Objective: To examine the effects of brief exposure to uncontrollable stress on fear conditioning, fear extinction, and dendritic morphology of pyramidal neurons in the infralimbic and prelimbic regions of the medial prefrontal cortex in mice
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Equipment2
Materials1
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Protocol Steps
Stress exposure
Mice exposed to uncontrollable stress through swim episodes
Note: Stress exposure ended 24 hours before fear conditioning began
View evidence from paper
“Exposure to three episodes of stress ending 24 h before fear conditioning significantly attenuated the rate of cued fear extinction”
Fear conditioning
Mice undergo fear conditioning with presentation of conditioned stimulus paired with unconditioned aversive stimulus
Note: Conducted 24 hours after stress exposure in stressed groups
View evidence from paper
“Extinction of conditioned fear responses is an active learning process resulting from the repeated presentation of a conditioned stimulus in the absence of the unconditioned aversive stimulus”
Fear extinction
Repeated presentation of conditioned stimulus in the absence of unconditioned aversive stimulus to assess extinction learning
Note: Rate of cued fear extinction was measured and compared between stressed and nonstressed controls
View evidence from paper
“Exposure to three episodes of stress ending 24 h before fear conditioning significantly attenuated the rate of cued fear extinction relative to nonstressed controls”
Cue and context recall assessment
Testing of cue and context recall following fear conditioning and extinction
Note: Stress did not affect cue or context recall
View evidence from paper
“did not affect fear conditioning or cue or context recall”
Neuronal morphology analysis
Analysis of dendritic morphology of pyramidal neurons in infralimbic and prelimbic regions using Golgi staining
Note: Examined terminal branches of apical and basilar dendrites; stress caused retraction of apical dendrites in IL neurons but not PL neurons
View evidence from paper
“Analysis of Golgi-stained neurons showed that one or three exposures to daily swim stress caused significant retraction of terminal branches of apical, but not basilar, dendrites of IL neurons”