Source Paper
The Role of Ventromedial Prefrontal Cortex in the Recovery of Extinguished Fear
Gregory J. Quirk, Gregory K. Russo, Jill L. Barron, Kelimer Lebron
Journal of Neuroscience • 2000
Conditioned Freezing Measurement
Objective: Measure conditioned freezing responses and bar-pressing suppression as indicators of fear acquisition and extinction, and assess recovery of fear responses after extinction
Gather these items before starting the experiment. Check off items as you prepare.
Equipment2
Not specified • Not specified • Not specified • Not mentioned
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Materials1
Not specified • Not specified • Not mentioned • Not mentioned
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Protocol Steps
Surgical lesion creation
Electrolytic vmPFC lesions were made before training in experimental group. Sham lesions were performed on control group.
Note: Some lesions spared the caudal infralimbic (IL) nucleus as a control condition
View evidence from paper
“electrolytic vmPFC lesions made before training on the acquisition, extinction, and recovery of conditioned fear responses”
Day 1 - Fear acquisition
Rats were trained with tone-footshock pairings to acquire conditioned fear responses
Note: vmPFC lesions had no effect on acquisition
View evidence from paper
“On Day 1 vmPFC lesions had no effect on acquisition or extinction of conditioned freezing and suppression of bar pressing”
Day 1 - Extinction training
Tone was presented repeatedly in the absence of shock to extinguish conditioned fear responses
Note: Extinction involves new learning accompanied by inhibition of conditioned responding rather than erasure of tone-shock association
View evidence from paper
“extinction of conditioned freezing and suppression of bar pressing. On Day 1 vmPFC lesions had no effect on acquisition or extinction”
Day 2 - Recovery testing
Measurement of recovery of conditioned fear responses after a long delay following extinction training
Note: Sham rats recovered only 27% of acquired freezing, while vmPFC-lesioned rats recovered 86%
View evidence from paper
“On Day 2 sham rats recovered only 27% of their acquired freezing, whereas vmPFC-lesioned rats recovered 86%”