Cold pressor pain reduces phobic fear but fear does not reduce pain

Pain Modulates Responses to Emotional Stimuli

Pain and emotion are common subjective experiences that play vital roles in daily life. Pain has been clinically confirmed to increase depressive mood. However, little is known about how pain modulates cognitive emotional judgment processing. A better understanding of this may help explain the effect of pain on the development of depressive moods. We recruited 30 adult participants to test their responses to pictures of scenes (Experiment 1) and faces (Experiment 2) that represented happy, neutral, and sad emotions, while experiencing painful (induced via topical capsaicin cream) and control (hand cream) treatments. Results showed that participants in the painful condition showed lower accuracy to emotional scene stimuli and longer reaction times to both emotional scene and face stimuli, relative to the control condition. In addition, the difference values of the reaction times between the painful and control conditions were larger for sad scenes than for happy or neutral scenes. These results suggest that pain alters attentional processing of emotional stimuli, especially with regards to sad scene stimuli, which may explain how painful stimuli affect the development of depressive moods.

The effect of disgust on pain sensitivity

Experiencing the emotion of disgust leads to delayed up-regulation of immune-related functions, increased core-body temperature and reduced appetite. These changes parallel those of the acute phase response, which occurs when a pathogen is detected by the immune system. Here we examined whether a further predicted aspect of the acute phase response is evident following disgust induction, namely increased pain sensitivity. Participants attended a two-session experiment. On one session they experienced an emotion induction (being randomly assigned to either disgust, negative or positive groups) and on the other they received a neutral control induction. Before and after each induction, and at 15 and 30min post-induction, participants engaged in a cold-pressor task, rating pain intensity at 10s intervals for 90s on each occasion. Relative to neutral control and pre-test, average pain intensity decreased then increased across time following the disgust induction, with the reverse pattern in the negative and positive emotion inductions. These findings are the first to suggest that disgust may lead to an increase in pain sensitivity over a time course paralleling changes observed for core-body temperature and immune-related function, although the mechanisms underpinning these effects remain to be identified.

Functional connectivity of pain-mediated affect regulation in Borderline Personality Disorder

Affective instability and self-injurious behavior are important features of Borderline Personality Disorder. Whereas affective instability may be caused by a pattern of limbic hyperreactivity paired with dysfunctional prefrontal regulation mechanisms, painful stimulation was found to reduce affective arousal at the neural level, possibly underlying the soothing effect of pain in BPD.We used psychophysiological interactions to analyze functional connectivity of (para-) limbic brain structures (i.e. amygdala, insula, anterior cingulate cortex) in Borderline Personality Disorder in response to painful stimulation. Therefore, we re-analyzed a dataset from 20 patients with Borderline Personality Disorder and 23 healthy controls who took part in an fMRI-task inducing negative (versus neutral) affect and subsequently applying heat pain (versus warmth perception).Results suggest an enhanced negative coupling between limbic as well as paralimbic regions and prefrontal regions, specifically with the medial and dorsolateral prefrontal cortex, when patients experienced pain in addition to emotional arousing pictures. When neutral pictures were combined with painful heat sensation, we found positive connectivity in Borderline Personality Disorder between (para-)limbic brain areas and parts of the basal ganglia (lentiform nucleus, putamen), as well areas involved in self-referential processing (precuneus and posterior cingulate).We found further evidence for alterations in the emotion regulation process in Borderline Personality Disorder, in the way that pain improves the inhibition of limbic activity by prefrontal areas. This study provides new insights in pain processing in BPD, including enhanced coupling of limbic structures and basal ganglia.