Biological psychology
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Biological psychology · Feb 2013
Randomized Controlled TrialHormonal contraception use alters stress responses and emotional memory.
Emotionally arousing material is typically better remembered than neutral material. Since norepinephrine and cortisol interact to modulate emotional memory, sex-related influences on stress responses may be related to sex differences in emotional memory. Two groups of healthy women - one naturally cycling (NC women, n=42) and one using hormonal contraceptives (HC women, n=36) - viewed emotionally arousing and neutral images. ⋯ Compared to NC women, HC women exhibited significantly blunted stress hormone responses to the images and CPS. Recall of emotional images differed between HC and NC women depending on noradrenergic and cortisol responses. These findings may have important implications for understanding the neurobiology of emotional memory disorders, especially those that disproportionately affect women.
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Biological psychology · Feb 2013
Deficient safety learning characterizes high trait anxious individuals.
Trait anxiety is a well-established risk factor for developing anxiety disorders, but evidence for abnormal associative fear learning in high trait anxious (HTA) individuals is inconclusive. In part, this may due to limitations in the scope and measures used to assess fear learning. The current study therefore assessed fear learning across multiple response domains and multiple test phases in a two-day discriminative fear-conditioning paradigm. ⋯ HTA participants showed stronger fear on the startle response and distress ratings to the safety (CS(-)) but not to the threat stimulus (CS(+)) during acquisition, along with impaired extinction and re-extinction. Trait anxiety did not affect skin conductance responses and effects on UCS-expectancy were limited. We conclude that high trait anxiety may be characterized by deficient safety learning which in turn may promote persistent and generalized fear responses.
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Biological psychology · Jan 2013
Comparative StudyLearning to fear obstructed breathing: comparing interoceptive and exteroceptive cues.
The present study investigated interoceptive fear conditioning (IFC) to an interoceptive and exteroceptive conditional stimulus (CS) with a severe respiratory load applied for 30s as the unconditional stimulus (US). CSs were another, weak respiratory load in the intero-IFC study (N=74), and a neutral picture in the extero-IFC study (N=42). CSs preceded the US in the paired groups, whereas the unpaired groups received the same number of unpaired CSs and USs. ⋯ In the intero-IFC study, the CS-load was associated with larger startle blinks and a smaller decrease in respiratory rate and tidal volume in the paired compared to the unpaired group. In the extero-IFC study, the CS-picture evoked an increase in tidal volume and self-reported fear only in the paired group. In addition, startle potentiation during the CS-picture was greater for the paired than for the unpaired group.
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Recent studies on fear generalization have demonstrated that fear-potentiated startle and skin conductance responses to a conditioned stimulus (CS) generalize to similar stimuli, with the strength of the fear response linked to perceptual similarity to the CS. The aim of the present study was to extend this work by examining neural correlates of fear generalization. ⋯ We then replicated this effect in a larger independent sample (N=25). Activation in the insula, anterior cingulate, right supplementary motor cortex and caudate increased reactivity as generalization stimuli (GS) were more similar to the CS, consistent with participants' overall ratings of perceived shock likelihood and pupillary response to each stimulus.
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Biological psychology · Oct 2012
Randomized Controlled TrialFear extinction in humans: effects of acquisition-extinction delay and masked stimulus presentations.
Fear extinction can be viewed as an inhibitory learning process. This is supported by post-extinction phenomena demonstrating the return of fear, such as reinstatement. Recent work has questioned this account, claiming that extinction initiated immediately after fear acquisition can abolish the return of fear. ⋯ During extinction, we manipulated CS contingency awareness by presenting two of the CSs (one CS+, one CS-) under non-masked conditions and the other two CSs under masked conditions. Compared to delayed extinction, immediate extinction of non-masked CSs promoted less extinction of fear-potentiated startle and shock expectancy ratings and less reinstatement of fear-potentiated startle without affecting shock expectancy ratings. Critically, future research should clarify how the differences between immediate and delayed extinction in within-session extinction modulate the recovery of fear.