Double Dissociation between the Involvement of the Bed Nucleus of the Stria Terminalis and the Central Nucleus of the Amygdala in Startle Increases Produced by Conditioned versus Unconditioned Fear
Objective: Measure acoustic startle response amplitude enhancement in the presence of cues previously paired with shock (fear-potentiated startle) to examine neuroanatomical substrates of conditioned fear responses
Materials & Equipment Checklist
6 items1 from ConductScience
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Equipment4
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Protocol Steps
View Abstract
The amplitude of the acoustic startle response is reliably enhanced when elicited in the presence of bright light (light-enhanced startle) or in the presence of cues previously paired with shock (fear-potentiated startle). Light-enhanced startle appears to reflect an unconditioned response to an anxiogenic stimulus, whereas fear-potentiated startle reflects a conditioned response to a fear-eliciting stimulus. We examine the involvement of the basolateral nucleus of the amygdala, the central nucleus of the amygdala, and the bed nucleus of the stria terminalis in both phenomena. Immediately before light-enhanced or fear-potentiated startle testing, rats received intracranial infusions of the AMPA receptor antagonist 2,3-dihydroxy-6-nitro-7-sulphamoylbenzo(F)-quinoxaline (3 μg) or PBS. Infusions into the central nucleus of the amygdala blocked fear-potentiated but not light-enhanced startle, and infusions into the bed nucleus of the stria terminalis blocked light-enhanced but not fear-potentiated startle. Infusions into the basolateral amygdala disrupted both phenomena. These findings indicate that the neuroanatomical substrates of fear-potentiated and light-enhanced startle, and perhaps more generally of conditioned and unconditioned fear, may be anatomically dissociated.
1
Fear conditioning with shock-paired cues
Rats are exposed to cues that are paired with electrical shock to establish conditioned fear associations
Not specifiedNot specified
Note: This establishes the fear-eliciting stimulus for later testing
View evidence from paper
“in the presence of cues previously paired with shock (fear-potentiated startle)”
2
Intracranial drug infusion
Immediately before testing, rats receive intracranial infusions of either AMPA receptor antagonist (3 μg) or PBS vehicle control into target brain regions
Immediately before testingNot specified
Note: Infusions target basolateral nucleus of amygdala, central nucleus of amygdala, or bed nucleus of stria terminalis
View evidence from paper
“Immediately before light-enhanced or fear-potentiated startle testing, rats received intracranial infusions of the AMPA receptor antagonist 2,3-dihydroxy-6-nitro-7-sulphamoylbenzo(F)-quinoxaline (3 μg) or PBS”
3
Fear-potentiated startle testing
Acoustic startle stimuli are presented in the presence of cues previously paired with shock, and startle response amplitude is measured
Note: Measures conditioned fear response; compared to light-enhanced startle (unconditioned response)
View evidence from paper
“The amplitude of the acoustic startle response is reliably enhanced when elicited in the presence of cues previously paired with shock (fear-potentiated startle)”
4
Light-enhanced startle testing
Acoustic startle stimuli are presented in the presence of bright light, and startle response amplitude is measured