Source Paper
Activity in Prelimbic Cortex Is Necessary for the Expression of Learned, But Not Innate, Fears
Kevin A. Corcoran, Gregory J. Quirk
Journal of Neuroscience • 2007
Innate Fear Response to Predator
Objective: Measurement of freezing behavior in response to cat exposure to assess innate fear and determine whether prelimbic cortex activity is necessary for expression of innate versus learned fears
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Equipment2
Materials1
Not specified • Not specified • Not specified • Not specified
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Protocol Steps
Fear conditioning with footshock
Rats are exposed to a tone and context paired with footshock to establish learned fear associations
Note: This establishes the learned fear condition that will be tested later
View evidence from paper
“a tone and a context that had been previously paired with footshock (learned fear)”
Prelimbic inactivation during fear expression
Tetrodotoxin is used to inactivate the prelimbic cortex during expression of fear to measure effects on freezing behavior
Note: Inactivation reduces freezing to learned fear stimuli but not to innate fear stimulus
View evidence from paper
“Inactivation of PL reduced freezing to both a tone and a context that had been previously paired with footshock (learned fear) but had no effect on freezing to a cat (innate fear)”
Measurement of freezing to learned fear stimuli
Freezing behavior is measured in response to tone and context previously paired with footshock after prelimbic inactivation
Note: Freezing is reduced when PL is inactivated
View evidence from paper
“Inactivation of PL reduced freezing to both a tone and a context that had been previously paired with footshock”
Measurement of freezing to innate fear stimulus
Freezing behavior is measured in response to cat exposure after prelimbic inactivation
Note: Freezing to cat is not affected by PL inactivation, indicating PL is not necessary for innate fear expression
View evidence from paper
“had no effect on freezing to a cat (innate fear)”
Prelimbic inactivation before conditioning
Tetrodotoxin is used to inactivate prelimbic cortex before fear conditioning to test effects on fear memory acquisition
Note: Inactivation before conditioning does not prevent formation of fear memories
View evidence from paper
“Inactivation of PL before conditioning, however, did not prevent the formation of auditory or contextual fear memories”