Anticipation Of Aversive Stimuli Research Articles

Association between startle reactivity to uncertain threats and structural brain volume.

Sensitivity to uncertain threat (U-threat) is a clinically important individual difference factor in multiple psychopathologies. Recent studies have implicated a specific frontolimbic circuit as a key network involved in the anticipation of aversive stimuli. In particular, the insula, thalamus, and dorsal anterior cingulate cortex (dACC) have recently been found to be robustly activated by anticipation of U-threat. However, no study to date has examined the association between U-threat reactivity and structural brain volume. In the present study, we utilized a pooled sample of 186 young adult volunteers who completed a structural MRI scan and the well-validated No-Predictable-Unpredictable (NPU) threat of electric shock task. Startle eyeblink potentiation was collected during the NPU task as an objective index of aversive reactivity. ROI-based analyses revealed that increased startle reactivity to U-threat was associated with reduced gray matter volume in the right insula and bilateral thalamus, but not the dACC. These results add to a growing literature implicating the insula and thalamus as core nodes involved in individual differences in U-threat reactivity.

Brain activity during pursuit and goal-conflict threat avoidance in major depressive disorder.

Threat avoidance is a prominent symptom of affective disorders, yet its biological basis remains poorly understood. Here, we used a validated task, the Joystick Operated Runway Task (JORT), combined with fMRI, to explore whether abnormal function in neural circuits responsible for avoidance underlies these symptoms. Eighteen individuals with major depressive disorder (MDD) and 17 unaffected controls underwent the task, which involved using physical effort to avoid threatening stimuli, paired with mild electric shocks on certain trials. Activity during anticipation and avoidance of threats was explored and compared between groups. Anticipation of aversive stimuli was associated with significant activation in the dorsal anterior cingulate cortex, superior frontal gyrus, and striatum, while active avoidance of aversive stimuli was associated with activity in dorsal anterior cingulate cortex, insula, and prefrontal cortex. There were no significant group differences in neural activity or behavioral performance on the JORT; however, participants with depression reported more dread while being chased on the task. The JORT effectively identified neural systems involved in avoidance and anticipation of aversive stimuli. However, the absence of significant differences in behavioral performance and activation between depressed and non-depressed groups suggests that MDD is not associated with abnormal function in these networks. Future research should investigate the basis of passive avoidance in major depression. Further, the JORT should be explored in patients with anxiety disorders, where threat avoidance may be a more prominent characteristic of the disorder.

(631): Validation of a high-throughput mouse behavioral testing protocol and application to the BXD genetic reference population for gene mapping of multiple pain traits

Genetic factors contribute to individual differences in pain sensitivity in humans and nociception in animals. Molecular and behavioral characterization of mouse genetic reference populations including recombinant inbred (RI) mice can be used to determine the responsible genes, their mechanistic effects, and the specific tissues involved. High-throughput behavioral testing protocols are required for efficient assessment of mouse nociception in large populations and mutant screens. These often controversial protocols involve repeated testing, which via habituation to stressors or anticipation of aversive stimuli may interact with organismic variables including sex to mimic or confound the effects of genetic variation.

Direct Activation of the Ventral Striatum in Anticipation of Aversive Stimuli

The brain “reward” system, centered on the limbic ventral striatum, plays a critical role in the response to pleasure and pain. The ventral striatum is activated in animal and human studies during anticipation of appetitive/pleasurable events, but its role in aversive/painful events is less clear. Here we present data from three human fMRI studies based on aversive conditioning using unpleasant cutaneous electrical stimulation and show that the ventral striatum is reliably activated. This activation is observed during anticipation and is not a consequence of relief after the aversive event. Further, the ventral striatum is activated in anticipation regardless of whether there is an opportunity to avoid the aversive stimulus or not. Our data suggest that the ventral striatum, a crucial element of the brain “reward” system, is directly activated in anticipation of aversive stimuli.

Electrodermal hyporeactivity and antisocial behavior: does anxiety mediate the relationship?

Electrodermal hyporeactivity in the anticipation of aversive stimuli is a highly reliable correlate of diagnosed psychopathy and undersocialized aggressive conduct disorder (UACD), and it has been interpreted as reflecting a weak behavioral inhibition system (BIS) as conceptualized in Gray’s work (e.g., in: Royce, J.R. (Ed.), Multivariate Analysis and Psychological Theory. Academic Press, New York, NY, p. 409, 1973). This interpretation predicts that electrodermal hyporeactivity should be associated with a single dimension of temperament involving both low anxiety and behavioral disinhibition. However, temperament scales identify separate dimensions of trait anxiety/neuroticism and inhibitory control, and most investigators have assumed that the BIS is associated with the trait anxiety/neuroticism dimension. The present review supports the view that electrodermal hyporeactivity is associated with both low anxiety and disinhibition, as expected, and, possibly, with poor control of emotional expression. Additionally, electrodermal hyporeactivity appears to relate to an impulsivity dimension among psychopaths rather than to the core personality features of psychopathy. Recent findings raise the possibility that psychopaths suffer from a broader deficit (sometimes described as an executive function deficit) than a weak BIS and that electrodermal hyporeactivity might relate to this broader deficit. It is proposed that problems with impulsivity are more strongly documented than the broader concept of executive function deficits and that a primary disinhibition can produce secondary executive function deficits. A disinhibitory deficit is consistent with the weak BIS hypothesis. Overall, the results appear to be consistent with the electrodermal hyporeactivity-weak BIS hypothesis, but many issues remain to be resolved.

Neurons in the macaque anterior cingulate cortex activate during anticipation of aversive stimuli

Neurons in the macaque anterior cingulate cortex activate during anticipation of aversive stimuli

Electrodermal and Cardiovascular Evidence of a Coping Response in Psychopaths

Hare (1978) has suggested that psychopaths may possess particularly effective coping mechanisms in the presence of impending aversive stimulation. These mechanisms may serve to attenuate anxiety so that the psychopath's behavior is less easily controlled by aversive consequences. To test this hypothesis, the heart rate (HR) and skin conductance level (SCL) of psychopaths and nonpsychopaths were compared across two countdown tasks. In Tasks 1, subjects heard a 120-db. tone following the countdown. In Task 2, subjects prevented the tone externally by pressing a button immediately following the countdown. The typical response pattern of psychopaths was present in Task 1, where they demonstrated increases in HR but relatively no increase in SCL. This response pattern dissipated, however, in Task 2 when the need to “cope” internally was removed. These results confirm the hypothesis that psychopaths may employ an effective coping response in anticipation of aversive stimuli.