Abstract
The present study examined the effects of sustained anticipatory anxiety on the affective modulation of the eyeblink startle reflex. Towards this end, pleasant, neutral and unpleasant pictures were presented as a continuous stream during alternating threat-of-shock and safety periods, which were cued by colored picture frames. Orbicularis-EMG to auditory startle probes and electrodermal activity were recorded. Previous findings regarding affective picture valence and threat-of-shock modulation were replicated. Of main interest, anticipating aversive events and viewing affective pictures additively modulated defensive activation. Specifically, despite overall potentiated startle blink magnitude in threat-of-shock conditions, the startle reflex remained sensitive to hedonic picture valence. Finally, skin conductance level revealed sustained sympathetic activation throughout the entire experiment during threat- compared to safety-periods. Overall, defensive activation by physical threat appears to operate independently from reflex modulation by picture media. The present data confirms the importance of simultaneously manipulating phasic-fear and sustained-anxiety in studying both normal and abnormal anxiety.
Highlights
A large body of evidence supports the notion that the startle reflex is modulated by defensive system activation
Startle reflex was modulated by picture valence, F(2,64) = 8.13, p,.001, e =
Post-hoc tests revealed that blink magnitude for unpleasant pictures was potentiated as compared to pleasant pictures, F(1,32) = 17.38, p,.001, and larger but not significantly different from neutral pictures, F(1,32) = 2.08, p =
Summary
A large body of evidence supports the notion that the startle reflex is modulated by defensive system activation. The startle reflex is potentiated as compared to control conditions, for instance in aversive conditioning paradigms [1] or when participants are verbally instructed that they might receive an electric shock during sustained threat periods [2]. During passive picture viewing, the startle reflex is potentiated for unpleasant images, and inhibited for pleasant contents [3]. A recent study examined startle reflexes in the context of pleasant and unpleasant pictures signaling either threat-of-shock or safety [4]. When pleasant pictures served as threat cues, startle reflex was potentiated as compared to safety condition. Revealing a valencespecific effect of anticipatory anxiety on affective picture viewing, facilitated processing of pleasant cues was observed during threatof-shock compared to safety conditions
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