Source Paper
Facilitation of Conditioned Fear Extinction by Systemic Administration or Intra-Amygdala Infusions of d-Cycloserine as Assessed with Fear-Potentiated Startle in Rats
David L. Walker, Kerry J. Ressler, Kwok-Tung Lu, Michael Davis
Journal of Neuroscience • 2002
Fear-Potentiated Startle
Objective: Measurement of increased startle response in the presence versus absence of a conditioned light stimulus to assess fear levels and evaluate effects of d-cycloserine on fear extinction
Gather these items before starting the experiment. Check off items as you prepare.
Equipment1
Not specified • Not specified • Not specified • Not specified
Materials4
Software1
Not specified • Not specified
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Protocol Steps
Fear Conditioning
Rats received fear conditioning with paired presentations of light and footshock
Note: Light stimulus was 3.7 seconds, footshock was 0.4 mA
View evidence from paper
“Rats received 10 pairings of a 3.7 sec light and a 0.4 mA footshock (fear conditioning)”
Baseline Fear-Potentiated Startle Measurement
Fear-potentiated startle was measured before extinction training to establish baseline fear levels
Note: Measured as increased startle in presence versus absence of light
View evidence from paper
“Fear-potentiated startle (increased startle in the presence vs the absence of the light) was subsequently measured before and after”
Extinction Training - Variable Presentations
Rats received non-reinforced light presentations without shock to extinguish conditioned fear response
Note: Different groups received different numbers of extinction presentations
View evidence from paper
“30, 60, or 90 presentations of the light without shock (extinction training)”
Post-Extinction Fear-Potentiated Startle Measurement
Fear-potentiated startle was measured after extinction training to assess extinction effectiveness
Note: Compared to baseline measurements
View evidence from paper
“Fear-potentiated startle (increased startle in the presence vs the absence of the light) was subsequently measured before and after”
DCS Administration - Systemic Injection
d-cycloserine was injected systemically before extinction training at varying doses
Note: Three dose levels tested: 3.25, 15, or 30 mg/kg. DCS dose-dependently enhanced extinction
View evidence from paper
“DCS injections (3.25, 15, or 30 mg/kg) before 30 non-reinforced light exposures dose-dependently enhanced extinction”
HA-966 Administration - Blocking Experiment
HA-966 (glycine-recognition site antagonist) was administered to block DCS effects
Note: Used to verify that DCS effects were mediated through glycine-recognition site
View evidence from paper
“These effects were blocked by HA-966, an antagonist at the glycine-recognition site”
DCS Administration Before Testing
DCS was injected before fear-potentiated startle testing to determine if it affects startle measurement itself
Note: DCS did not alter fear-potentiated startle when injected before testing
View evidence from paper
“Neither DCS nor HA-966 altered fear-potentiated startle when injected before testing”
Intra-Amygdala DCS Infusion
d-cycloserine was infused directly into the amygdala to test local effects on fear extinction
Note: 10 μg/side infused; effects mimicked systemic administration
View evidence from paper
“The effect of systemic administration was mimicked by intra-amygdala DCS (10 μg/side) infusions”