Between the Devil and the Deep Blue Sea: Avoidance-Avoidance Competition Increases Pain-Related Fear and Slows Decision-Making

The Use of an FR1 Schedule Operant Approach-Avoidance Paradigm to Measure the Aversiveness of Neuropathic and Inflammatory Pain

Pain is a subjective, private, yet universal phenomenon that depends on a unique combination of sensory, affective, and evaluative characteristics. Although preclinical models have been used to understand much of pain physiology, the inability to communicate with animals limits affective and evaluative feedback and has constrained traditional behavioral methods to adequately represent and study the multidimensional pain experience. Therefore, this study sought to characterize the affective component of pain within a novel operant approach-avoidance paradigm (AAP) to determine which type of pain (inflammatory and neuropathic) may be more aversive. To reveal the possible differences in pain aversiveness within the AAP paradigm, animals received bilateral inflammatory and neuropathic pain conditions and were given the choice to a) forgo appetitive reward by not receiving noxious stimulus of either inflammatory or neuropathic conditions or b) receive noxious stimulus in exchange for an appetitive reward. Although all pain conditions produced significant hypersensitivity, the AAP results revealed there was no preference in the stimulation of a specific paw in the bilateral pain conditions. The finding suggests that despite unique clinical pain characteristics for inflammatory and neuropathic conditions, the lack of observable differences in the pain conditions may not necessarily equate to the overall similarity in aversiveness, but rather that the fixed ratio (FR1) paradigm presentation allowed appetitive reward to be more salient, highlighting the complexities of competing motivational drives of pain and hunger when satiating hunger is always guaranteed. Thus, future studies should seek to further tease apart this relationship with a different schedule and food-controlled methodologies. The development of such preclinical approaches can thoroughly investigate the intricacy of competing drives and likely reveal important information regarding the complexity of pain, enhancing our understanding of pain perception in individuals suffering from comorbid pain states.

Avoidance Behavioral Difference in Acquisition and Extinction of Pain-Related Fear

Fear of movement-related pain leads to two types of avoidance behavior: excessive avoidance and pain-inhibited movement. Excessive avoidance is an absence of movement by fear, and pain-inhibited movements involve a change in motor behavior for the purpose of protecting the painful part. Here, we sought to clarify the acquisition process and adaptation of fear for each avoidance behavior. Thirty-one female and 13 male (age 20.9 ± 2.1 years) subjects could decide persistent behaviors: approach with an intense pain stimulus, pain-inhibited movement with weak pain stimulus, or excessive avoidance with no pain in acquisition and test phases. In the subsequent extinction phase, the pain stimulus was omitted. Subjects were divided into an approach group (n = 24), a pain-inhibited movement group (n = 10), and an excessive avoidance group (n = 10) by cluster analysis. The response latencies in approach and pain-inhibited movement groups were not affected by conditioned pain. The subjects in the excessive avoidance group exhibited delayed response latencies, and their high-fear responses remained in the acquisition, test, and extinction phases. In addition, the excessive avoidance group showed high harm avoidance and high trait anxiety. This study demonstrated that differences in pain-related avoidance behaviors are affected by psychological traits. Pain-related excessive avoidance behavior indicated a maladaptive fear, but pain-inhibited movement did not.

Genito-Pelvic Pain Through a Dyadic Lens: Moving Toward an Interpersonal Emotion Regulation Model of Women's Sexual Dysfunction

Researchers and clinicians alike widely acknowledge the inherently interpersonal nature of women's sexual dysfunctions given that both partners impact and are impacted by these difficulties. Yet theoretical models for understanding the role of interpersonal factors in women's sexual dysfunctions are severely lacking and have the potential to guide future research and inform more effective interventions. The most widely studied sexual dysfunction in women that has espoused a dyadic approach by including both members of affected couples is genito-pelvic pain/penetration disorder (GPPPD). In this article we use the example of GPPPD to introduce a novel interpersonal emotion regulation model of women's sexual dysfunction. We first review current knowledge regarding distal and proximal interpersonal factors in GPPPD. Then, we describe our theoretical model and consider relevant pain and sex-related research on emotion regulation processes-emotional awareness, expression, and experience-in the context of GPPPD, including sexual function, satisfaction, and distress. Next, we review how existing theories from the fields of chronic pain and sex and relationships research have informed our model and how our model further builds on them. Finally, we discuss the implications of our model and its applications, including to other sexual dysfunctions in women.

Winning or not losing? The impact of non-pain goal focus on attentional bias to learned pain signals

Background and aims

Insights into the nature of cognitive bias, including attentional bias to threat signals, are considered pivotal to understanding (chronic) pain and related distress. It has been put forward that attention to pain-related threat is normally dynamic and relates to the motivational state of the individual. In this experiment we aimed (i) to replicate the finding that attentional bias for pain signals in healthy participants can be reduced when a non-pain goal is pursued, and (ii) to extend this finding by taking into account the outcome focus of the non-pain goal. We hypothesised that the reduction in attentional bias for pain signals by concurrent non-pain goal pursuit would be stronger with non-pain prevention goals than with promotion goals.

Methods

Healthy university students performed an attentional bias task (i.e. spatial cueing task) containing visual cues that signalled the possible occurrence of a painful stimulus (electrocutaneous stimulus at tolerance level) or its absence, in combination with a non-pain goal task (i.e. digit naming task). The non-pain goal was either related to acquiring a positive outcome (gaining money depending on digit-naming performance; promotion goal group, n=31) or related to avoiding a negative outcome (losing money; prevention goal group, n=31). A standard attentional bias task served as the control condition (control group, n=31).

Results

Spatial cueing effects were larger for pain cues than for no-pain cues, indicating attentional bias for pain signals. The pattern of results suggests that this effect was indeed reduced in the goal groups as compared to the control group, but there was no significant group difference.

Conclusions

We found no statistically-significant evidence for the impact of non-pain goal pursuit or outcome focus on pain-related attentional bias. At best, there were indications of a reduced attentional bias for pain signals with non-pain goal pursuit that was either promotion- or prevention focused.

Implications

These data add to the small but growing body of literature on the assumed relevance of motivational context in explaining variations in attentional bias. The results trigger new questions on the nature and assessment of pain-related attentional bias, and more specifically attentional bias for fear-conditioned pain signals (versus safety signals), from a motivational perspective.

Assessing the aversive nature of pain with an operant approach/avoidance paradigm

Preclinical pain assessments can be criticized for failing to adequately characterize the human clinical pain experience. Although recent assessments have improved upon this shortcoming, there are still significant limitations. One concern is that current procedures fail to examine underlying motivational drives related to pain. Therefore, we used a novel approach-avoidance paradigm that allowed a rat to either satisfy hunger or avoid noxious stimulation to reveal prioritizing of motivational drives. The operant paradigm utilized a single lever that the animal pressed for appetitive reward (approach). The lever press was associated with mechanical stimulation of an inflamed paw induced by subcutaneous injection of carrageenan (avoidance). The results revealed that carrageenan-injected animals had a significant suppression of lever pressing and, in addition, had a longer latency to approach and press a lever for appetitive reward. The pattern of operant behavioral responses indicates that the motivation to avoid pain superseded the motivation to alleviate hunger. Utilization of approach-avoidance paradigms, such as this one, can allow researchers to unravel the complexities of the pain experience with the goal of enhancing translation to clinical efficacy.

Predictors and social consequences of daily pain expectancy among adults with chronic pain

Previous research suggests that for people living with chronic pain, pain expectancy can undermine access to adaptive resources and functioning. We tested and replicated the unique effect of pain expectancy on subsequent pain through 2 daily diary studies. We also extended previous findings by examining cognitive and affective antecedents of pain expectancy and the consequences of pain expectancy for daily social enjoyment and stress. In study 1, 231 individuals with rheumatoid arthritis completed 30 end-of-day diaries. Results of multilevel structural equation model showed that controlling for today's pain, pain expectancy predicted next day pain. In study 2, diary assessments of affective, cognitive, and social factors were collected during the morning, afternoon, and evening for 21 days from a sample of 220 individuals with fibromyalgia. Results showed that both positive affect and the extent to which pain interfered with daily activities in the afternoon predicted evening pain expectancy in the expected direction. However, negative affect and pain coping efficacy were not associated with pain expectancy. Consistent with study 1, more than usual evening pain expectancy was related to greater next morning pain. We also found that next morning pain predicted next afternoon social enjoyment but not social stress. The findings of these 2 studies point to the importance of promoting positive affect and reducing pain expectancy as a way of decreasing the detrimental effect of chronic pain on enjoyable social experiences.