Biological psychology
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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.
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Biological psychology · Oct 2012
Should it matter when we record? Time of year and time of day as factors influencing frontal EEG asymmetry.
Resting frontal encephalographic (EEG) asymmetry, often conceptualized as a trait marker for depression, is influenced by occasion-specific factors, including time of year and the time of day of the recording session as demonstrated recently (Peterson and Harmon-Jones, 2009). The current study examined the influence of seasonal and chronological variables on resting frontal asymmetry, and also assessed whether different reference montages or surface transformations were equally susceptible to these influences. ⋯ Time awake at recording, however, was an important moderating variable of the relationship between photoperiod and time of day. EEG asymmetry scores based on current-source density (CSD) transformed data, however, appeared less vulnerable to these influences, providing further evidence to suggest that the CSD transform may be advantageous for examining stable trait estimates of frontal EEG asymmetry.
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Biological psychology · Oct 2012
Differential effects of mild chronic stress on cortisol and S-IgA responses to an acute stressor.
While acute stress is adaptive in the short term, chronic stress may interfere with HPA axis functioning and self-regulation that can, in turn, alter the body's immune response. Several studies suggest that acute and chronic stress consistently increase cortisol levels; however, the same cannot be said about S-IgA levels. ⋯ Furthermore, we find that during the period of chronic mild stress, the perception of stress is related to increased cortisol response to an acute stressor. Combined, these findings shed light on the impact of increased background stress on acute stress responses.