Increased anterior insula activity in anxious individuals is linked to diminished perceived control.

Individuals with high-trait anxiety frequently report decreased perceived control. However, it is unclear how these processes are instantiated at a neural level. Prior research suggests that individuals prone to anxiety may have exaggerated activity in the anterior insula and altered activity in the cingulate cortex during anticipation of aversive events. Thus, we hypothesized that anxiety proneness influences anterior insula activation during anticipation of unpredictable threat through decreased perceived control. Forty physically healthy adults underwent neuroimaging while they explored computer-simulated contexts associated either with or without the threat of an unpredictable shock. Skin conductance, anxiety ratings and blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging were used to assess responses to threat versus no threat. Perceived control was measured using the Anxiety Control Questionnaire-Revised. Mediation analysis examined how anxiety proneness influenced BOLD activity. Anticipation of unpredictable threat resulted in increased skin conductance responses, anxiety ratings and enhanced activation in bilateral insula, anterior midcingulate cortex (aMCC) and bed nucleus of the stria terminalis. Individuals with greater anxiety proneness and less perceived control showed greater activity in dorsal anterior insula (dAI). Perceived control mediated the relationship between anxiety proneness and dAI activity. Increased dAI activity was associated with increased activity in aMCC, which correlated with increased exploratory behavior. Results provide evidence that exaggerated insula activation during the threat of unpredictable shock is directly related to low perceived control in anxiety-prone individuals. Perceived control thus may constitute an important treatment target to modulate insula activity during anxious anticipation in anxiety-disordered individuals.

Pain and emotion: effects of affective picture modulation.

OBJECTIVE AND METHODS: Two experiments examined the impact of viewing unpleasant, pleasant, and neutral photographic slides on cold-pain perception in healthy men and women. In each experiment, participants viewed one of three slide shows (experiment 1 = fear, disgust, or neutral; experiment 2 = erotic, nurturant, or neutral) immediately before a cold-pressor task. Skin conductance and heart rate were recorded during the slide shows, whereas visual analog scale ratings of pain intensity and unpleasantness thresholds and pain tolerance were recorded during the cold-pressor task. RESULTS: Viewing fear and disgust slides decreased pain intensity and unpleasantness thresholds, but only the fear slides decreased pain tolerance. In contrast, viewing erotic, but not nurturant, slides increased pain intensity and unpleasantness threshold ratings on the visual analog scale in men, whereas neither nurturant nor erotic slides altered pain tolerance. CONCLUSIONS: These results are consistent with a motivational priming model that predicts that unpleasant affective states should enhance pain and that pleasant affective states should attenuate it.

Noise stress and human pain thresholds: divergent effects in men and women.

Considerable animal research suggests that exposure to noxious and nonnoxious fear-inducing stimuli can produce hypoalgesia. Although this effect is thought to generalize across species, only a few studies have examined the pain modulatory effects of nonnoxious fear-eliciting stimuli in humans. The present study examined whether exposure to a series of loud noise bursts would produce a fear-related hypoalgesia in male and female human subjects. Both subjective and physiologic measures (skin conductance level, heart rate) indicated that noise exposure resulted in fear, sympathetic arousal, and decreased pain reactivity in women (n = 20). In contrast, men (n = 20) did not experience fear or physiologic arousal, but reacted with surprise and increased pain reactivity. These findings provide additional evidence that hypoalgesia is mediated by fear and physiologic arousal. Although future studies should directly manipulate surprise, it appears that surprise without fear and physiologic arousal might enhance pain processing.