Neural processing of sensory and emotional-communicative information associated with the perception of vicarious pain

The role of external factors in affect-sharing and their neural bases

Affect-sharing, the ability to vicariously feel another person's emotions, is the primary component of empathy that is typically thought to rely on the observer's capacity to feel the emotions of others. However, external signals, such as the target's physical characteristics, have been demonstrated to influence affect-sharing in the neuroscientific literature that speaks to the underappreciated role of external factors in eliciting affect-sharing. We consider factors that influence affect-sharing, including physical cues, emotional cues, situational factors, and observer-target relationships, as well as the neural circuits involved in these processes. Our review reveals that, while neural network activation is primarily responsible for processing affect-sharing, external factors also co-activate a top-down cognitive processing network to modulate the conscious process of affect-sharing. From this knowledge, an integrative framework of external factor interactions with affect-sharing are explained in detail. Finally, we identify critical areas for future research in social and affective neuroscience, including research gaps and incorporation of ecologically valid paradigms.

Vicarious facilitation of facial responses to pain

INTRODUCTION

Observing facial expressions of pain has been shown to lead to increased subjective, neural and autonomic pain responses. Surprisingly, these vicarious facilitation effects on its corresponding response channel, namely facial responses to pain have mostly been neglected. We aim to examine whether the prior exposure to facial expressions of pain leads to a facilitation of facial responses to experimental pain; and whether this facilitation is linked to the valence (pain vs. neutral expression) or also linked to specific motor-features of the facial pain expressions (different facial muscle movements).

METHOD

Subjective (intensity and unpleasantness ratings) and facial responses (Facial Action Coding System) of 64 participants (34 female) to painful and non-painful heat stimuli were assessed. Before each heat stimulus, video clips of computer-generated facial expressions (three different pain expressions and a neutral expression) were presented.

RESULTS

The prior exposure to facial expressions of pain led to increased subjective and facial responses to pain. Further, vicarious pain facilitation of facial responses was significantly correlated with facilitation of unpleasantness ratings. We also found evidence that this vicarious facilitation of facial responses was not only linked to the presentation of pain versus neutral expressions but also to specific motor-features of the pain cue (increase in congruent facial muscle movements).

DISCUSSION

Vicarious pain facilitation was found for subjective and facial responses to pain. The results are discussed with reference to the motivational priming hypothesis as well as with reference to motor priming.

SIGNIFICANCE

Our study uncovers evidence that facial pain responses are not only influenced by motivational priming (similar to other types of pain responses), but also by motor-priming. These findings shed light on the complexity - ranging from social, affective and motor mechanisms - underling vicarious facilitation of pain.

Brain stimulation targets for chronic pain: Insights from meta-analysis, functional connectivity and literature review

Noninvasive brain stimulation (NIBS) techniques have demonstrated their potential for chronic pain management, yet their efficacy exhibits variability across studies. Refining stimulation targets and exploring additional targets offer a possible solution to this challenge. This study aimed to identify potential brain surface targets for NIBS in treating chronic pain disorders by integrating literature review, neuroimaging meta-analysis, and functional connectivity analysis on 90 chronic low back pain patients. Our results showed that the primary motor cortex (M1) (C3/C4, 10-20 EEG system) and prefrontal cortex (F3/F4/Fz) were the most used brain stimulation targets for chronic pain treatment according to the literature review. The bilateral precentral gyrus (M1), supplementary motor area, Rolandic operculum, and temporoparietal junction, were all identified as common potential NIBS targets through both a meta-analysis sourced from Neurosynth and functional connectivity analysis. This study presents a comprehensive summary of the current literature and refines the existing NIBS targets through a combination of imaging meta-analysis and functional connectivity analysis for chronic pain conditions. The derived coordinates (with integration of the international electroencephalography (EEG) 10/20 electrode placement system) within the above brain regions may further facilitate the localization of these targets for NIBS application. Our findings may have the potential to expand NIBS target selection beyond current clinical trials and improve chronic pain treatment.

Graded brain fMRI response to somatic and visual acupuncture stimulation

Increased stimulation can enhance acupuncture clinical response; however, the impact of acupuncture stimulation as "dosage" has rarely been studied. Furthermore, acupuncture can include both somatic and visual components. We assessed both somatic and visual acupuncture dosage effects on sensory ratings and brain response. Twenty-four healthy participants received somatic (needle inserted, manually stimulated) and visual (needle video, no manual stimulation) acupuncture over the leg at three different dosage levels (control, low-dose, and high-dose) during functional magnetic resonance imaging (fMRI). Participants reported the perceived deqi sensation for each acupuncture dose level. Blood-oxygen-level dependent imaging data were analyzed by general linear model and multivariate pattern analysis. For both somatic and visual acupuncture, reported deqi sensation increased with increased dosage of acupuncture stimulation. Brain fMRI analysis demonstrated that higher dosage of somatic acupuncture produced greater brain responses in sensorimotor processing areas, including anterior and posterior insula and secondary somatosensory cortex. For visual acupuncture, higher dosage of stimulation produced greater brain responses in visual-processing areas, including the middle temporal visual areas (V5/MT+) and occipital cortex. Psychophysical and psychophysiological responses to both somatic and visual acupuncture were graded in response to higher doses. Our findings suggest that acupuncture response may be enhanced by the dosage of needling-specific and nonspecific components, represented by different neural mechanisms.

The impact of shift work on pain recognition, a robust ability among intensive care nurses

BACKGROUND

Pain empathy is essential for high-quality of care. The cognitive ability to identify and understand the pain in others remains underexplored in the context of hospital shift work. This study aimed to observe the early subliminal ability to detect pain in other faces and to investigate pain intensity evaluations during day and night shifts.

METHODS

Twenty-one nurses (31 ± 7 years, 20 women) from cardio-paediatric intensive care participated in this study. Eighteen nurses completed all testing in the morning and evening hours, before and after the 12-hour day and night shift. In the first test, the nurses had to decide if facial stimuli presented subliminally showed pain or not. During the second test, they consciously determined the intensity of the painful faces on a numerical scale. Sleep, sleepiness and empathy were also measured.

RESULTS

Recognition accuracy and pain sensitivity remained stable over time, only sensitivity increased following the work shift (F(1,15) = 7.10, p = 0.018). Intensity ratings remained stable. Sleepiness at the end of the night shift was negatively correlated with accuracy (ρ = -0.51, p = 0.018) and positively correlated with prior night shifts (ρ = -0.50, p = 0.022).

CONCLUSION

The judgement of facial pain expressions seems robust across shift types, only individual factors such as sleepiness interfere with pain recognition. Pain sensitivity may be enhanced during working hours.

SIGNIFICANCE STATEMENT

Some professions need to know how to assess pain 24/7 and a lack of sleep can disrupt the cognitive processes necessary for this assessment. Night shifts provoke a bias in pain management, and sleep deprivation, a decrease in pain evaluation. By conducting a repeated measure study in the field that applied a different paradigm (subliminal recognition of facial cues) we add evidence to the understanding of pain recognition and the impact of sleep deprivation on the early processing of pain in others.

Hmgb1 Silencing in the Amygdala Inhibits Pain-Related Behaviors in a Rat Model of Neuropathic Pain

Chronic pain presents a therapeutic challenge due to the highly complex interplay of sensory, emotional-affective and cognitive factors. The mechanisms of the transition from acute to chronic pain are not well understood. We hypothesized that neuroimmune mechanisms in the amygdala, a brain region involved in the emotional-affective component of pain and pain modulation, play an important role through high motility group box 1 (Hmgb1), a pro-inflammatory molecule that has been linked to neuroimmune signaling in spinal nociception. Transcriptomic analysis revealed an upregulation of Hmgb1 mRNA in the right but not left central nucleus of the amygdala (CeA) at the chronic stage of a spinal nerve ligation (SNL) rat model of neuropathic pain. Hmgb1 silencing with a stereotaxic injection of siRNA for Hmgb1 into the right CeA of adult male and female rats 1 week after (post-treatment), but not 2 weeks before (pre-treatment) SNL induction decreased mechanical hypersensitivity and emotional-affective responses, but not anxiety-like behaviors, measured 4 weeks after SNL. Immunohistochemical data suggest that neurons are a major source of Hmgb1 in the CeA. Therefore, Hmgb1 in the amygdala may contribute to the transition from acute to chronic neuropathic pain, and the inhibition of Hmgb1 at a subacute time point can mitigate neuropathic pain.

Brain responses to the vicarious facilitation of pain by facial expressions of pain and fear

Observing pain in others facilitates self-pain in the observer. Vicarious pain facilitation mechanisms are poorly understood. We scanned 21 subjects while they observed pain, fear and neutral dynamic facial expressions. In 33% of the trials, a noxious electrical stimulus was delivered. The nociceptive flexion reflex (NFR) and pain ratings were recorded. Both pain and fear expressions increased self-pain ratings (fear > pain) and the NFR amplitude. Enhanced response to self-pain following pain and fear observation involves brain regions including the insula (INS) (pain > fear in anterior part), amygdala, mid-cingulate cortex (MCC), paracentral lobule, precuneus, supplementary motor area and pre-central gyrus. These results are consistent with the motivational priming account where vicarious pain facilitation involves a global enhancement of pain-related responses by negatively valenced stimuli. However, a psychophysiological interaction analysis centered on the left INS revealed increased functional connectivity with the aMCC in response to the painful stimulus following pain observation compared to fear. The opposite connectivity pattern (fear > pain) was observed in the fusiform gyrus, cerebellum (I-IV), lingual gyrus and thalamus, suggesting that pain and fear expressions influence pain-evoked brain responses differentially. Distinctive connectivity patterns demonstrate a stronger effect of pain observation in the cingulo-insular network, which may reflect partly overlapping networks underlying the representation of pain in self and others.

The alterations in event-related potential responses to pain empathy in breast cancer survivors treated with chemotherapy

Background

Previous findings indicated that breast cancer patients often have dysfunction in empathy and other cognitive functions during or after chemotherapy. However, the manifestations and possible neuro-electrophysiological mechanisms of pain empathy impairment in breast cancer patients after chemotherapy were still unknown.

Objective

The current study aimed to investigate the potential correlations between pain empathy impairment and event-related potentials (ERP) in breast cancer patients undergoing chemotherapy.

Methods

Twenty-two breast cancer patients were evaluated on a neuropsychological test and pain empathy paradigm before and after chemotherapy, containing the Chinese version of the Interpersonal Reactivity Index (IRI-C), while recording ERP data.

Results

The empathic concern scores were lower and personal distress scores were higher on IRI-C task compared with those before chemotherapy (t = 3.039, p < 0.01; t = −2.324, p < 0.05, respectively). Meanwhile, the accuracy rates were lower than those before chemotherapy for both pain and laterality tasks on the pain empathy paradigm (F = 5.099, P = 0.035). However, the response time was no significant differences before and after chemotherapy (F = 0.543, P = 0.469). Further, the amplitude of the N1 component was significantly increased (F = 38.091, P < 0.001), and the amplitude of the P2 component was significantly decreased (F = 15.046, P = 0.001) in the subsequent ERP study. A linear mixed effect model was used to analyze the correlation, the average amplitude of N1 and P2 were positively correlated with the accuracy rates in laterality tasks (r = 1.765, r = 1.125, respectively, P < 0.05).

Conclusion

The results indicated that pain empathy impairment was performed in chemotherapeutic breast cancer patients, which was possibly correlated to the changes of N1 and P2 components in ERP. These findings provide neuro-electrophysiological information about chemo-brain in breast cancer patients.

Sex Differences in CGRP Regulation and Function in the Amygdala in a Rat Model of Neuropathic Pain

The amygdala has emerged as a key player in the emotional response to pain and pain modulation. The lateral and capsular regions of the central nucleus of the amygdala (CeA) represent the “nociceptive amygdala” due to their high content of neurons that process pain-related information. These CeA divisions are the targets of the spino-parabrachio-amygdaloid pain pathway, which is the predominant source of calcitonin gene-related peptide (CGRP) within the amygdala. Changes in lateral and capsular CeA neurons have previously been observed in pain models, and synaptic plasticity in these areas has been linked to pain-related behavior. CGRP has been demonstrated to play an important role in peripheral and spinal mechanisms, and in pain-related amygdala plasticity in male rats in an acute arthritis pain model. However, the role of CGRP in chronic neuropathic pain-related amygdala function and behaviors remains to be determined for both male and female rats. Here we tested the hypothesis that the CGRP1 receptor is involved in neuropathic pain-related amygdala activity, and that blockade of this receptor can inhibit neuropathic pain behaviors in both sexes. CGRP mRNA expression levels in the CeA of male rats were upregulated at the acute stage of the spinal nerve ligation (SNL) model of neuropathic pain, whereas female rats had significantly higher CGRP and CGRP receptor component expression at the chronic stage. A CGRP1 receptor antagonist (CGRP 8-37) administered into the CeA in chronic neuropathic rats reduced mechanical hypersensitivity (von Frey and paw compression tests) in both sexes but showed female-predominant effects on emotional-affective responses (ultrasonic vocalizations) and anxiety-like behaviors (open field test). CGRP 8-37 inhibited the activity of CeA output neurons assessed with calcium imaging in brain slices from chronic neuropathic pain rats. Together, these findings may suggest that CGRP1 receptors in the CeA are involved in neuropathic pain-related amygdala activity and contribute to sensory aspects in both sexes but to emotional-affective pain responses predominantly in females. The sexually dimorphic function of CGRP in the amygdala would make CGRP1 receptors a potential therapeutic target for neuropathic pain relief, particularly in females in chronic pain conditions.

Adaptive Empathy: A Model for Learning Empathic Responses in Response to Feedback

Empathy is usually deployed in social interactions. Nevertheless, common measures and examinations of empathy study this construct in isolation from the person in distress. In this article we seek to extend the field of examination to include both empathizer and target to determine whether and how empathic responses are affected by feedback and learned through interaction. Building on computational approaches in feedback-based adaptations (e.g., no feedback, model-free and model-based learning), we propose a framework for understanding how empathic responses are learned on the basis of feedback. In this framework, adaptive empathy, defined as the ability to adapt one's empathic responses, is a central aspect of empathic skills and can provide a new dimension to the evaluation and investigation of empathy. By extending existing neural models of empathy, we suggest that adaptive empathy may be mediated by interactions between the neural circuits associated with valuation, shared distress, observation-execution, and mentalizing. Finally, we propose that adaptive empathy should be considered a prominent facet of empathic capabilities with the potential to explain empathic behavior in health and psychopathology.

Interoceptive attentiveness and autonomic reactivity in pain observation

Aim: This study explores interoceptive attentiveness (IA) influence on autonomic reactivity related to pain and self-regulation during situations evoking physiological mirroring for pain.Methods: 20 participants observed face/hand, painful/non-painful stimuli in an individual versus social condition while the autonomic response was measured [Electrodermal activity, Pulse Volume Amplitude (PVA), and Heart Rate (HR)] was measured. The sample was divided into experimental (EXP) subjects, required to focus on their interoceptive correlates while observing the stimuli, and the control (CNT) group. HR inter-beat interval (IBI), and HR Variability (HRV) were calculated.Results: Results showed high accuracy to painful and non-painful stimuli recognition. Regarding autonomic indices, higher PVA values were detected for hand painful versus non-painful stimuli, whereas for the EXP group a significant activation of IBI was found for face painful vs non-painful stimuli.Conclusion: In the context of observation of pain in others, PVA and IBI could be respectively markers of mirroring mechanisms and autonomic self-regulation mediated by IA.

Shared and distinct functional networks for empathy and pain processing: a systematic review and meta-analysis of fMRI studies

BACKGROUND

Empathy for pain is a complex phenomenon incorporating sensory, cognitive and affective processes. Functional neuroimaging studies indicate a rich network of brain activations for empathic processing. However, previous research focused on core activations in bilateral anterior insula (AI) and anterior cingulate/anterior midcingulate cortex (ACC/aMCC) which are also typically present during nociceptive (pain) processing. Theoretical understanding of empathy would benefit from empirical investigation of shared and contrasting brain activations for empathic and nociceptive processing.

METHOD

Thirty-nine empathy for observed pain studies (1112 participants; 527 foci) were selected by systematic review. Coordinate based meta-analysis (activation likelihood estimation) was performed and novel contrast analyses compared neurobiological processing of empathy with a comprehensive meta-analysis of 180 studies of nociceptive processing (Tanasescu et al., 2016).

RESULTS

Conjunction analysis indicated overlapping activations for empathy and nociception in AI, aMCC, somatosensory and inferior frontal regions. Contrast analysis revealed increased likelihood of activation for empathy, relative to nociception, in bilateral supramarginal, inferior frontal and occipitotemporal regions. Nociception preferentially activated bilateral posterior insula, somatosensory cortex and aMCC.

CONCLUSION

Our findings support the likelihood of shared and distinct neural networks for empathic, relative to nociceptive, processing. This offers succinct empirical support for recent tiered or modular theoretical accounts of empathy.

One's Interoception Affects the Representation of Seeing Others' Pain: A Randomized Controlled qEEG Study

Objective

This research demonstrates that interoceptive attentiveness (IA) can modulate cortical oscillations related to the emotional and cognitive representations of observing pain in others.

Methods

Twenty participants were required to observe painful/nonpainful stimuli in an individual versus the interactive condition during the recording of the electroencephalogram. The sample was divided into experimental (EXP) and control (CTR) groups, and the EXP group was explicitly required to direct the attention on its interoceptive correlates while observing the stimuli.

Results

Mixed repeated measures, analyses of variance, were applied to each EEG frequency band. Significant findings were obtained mainly for theta and beta bands for the two groups. A hemispheric lateralisation effect was found, with right lateralisation of the theta band for the EXP group when observing painful stimuli and enhanced left activation of theta and beta bands for the CTR group when observing nonpainful stimuli. For both groups, frontal cortical regions were significantly sensitive to social scenarios, while posterior parietal activation was found for stimuli depicting the individual condition.

Conclusions

The results suggest that IA might enhance the emotional representation of painful stimuli, highlighting their negative and unpleasant features in the EXP group, while the attention of the CTR group was mainly drawn to nonpainful stimuli in social and individual conditions, with a positive valence. The role of frontal regions in the processing of social stimuli through social cognition, inducing emotional mirroring and requiring deeper analysis of the social context, was underlined. We propose that IA could be trained for promoting emotion regulation and empathic response.

Probing the role of the right inferior frontal gyrus during Pain-Related empathy processing: Evidence from fMRI and TMS

Recent studies have suggested that the right inferior frontal gyrus (rIFG) may be involved in pain-related empathy. To verify the role of the rIFG, we performed a functional magnetic resonance imaging (fMRI) experiment to replicate previous research and further designed a noninvasive repetitive transcranial magnetic stimulation (rTMS) experiment to probe the causal role of the rIFG in pain-related empathy processing. We assigned 74 volunteers (37 females) to three groups. Group 1 (n = 26) performed a task in which participants were required to perceive pain in others (task of pain: TP) and we used fMRI to observe the activity of the rIFG during pain-related empathy processing. Then, we applied online rTMS to the rIFG and the vertex site (as reference site) to observe the performance of Group 2 (n = 24; performing TP) and Group 3 (n = 24; performing a control task of identifying body parts; task of body: TB). fMRI experiment demonstrated stronger activation in the rIFG than in the vertex during the perception of pain in others (p < .0001, Bonferroni-corrected). rTMS experiment indicated that when the rIFG was temporarily disrupted, participants perceived pain in others significantly more slowly (p < .0001, Bonferroni-corrected) than when the vertex was disrupted. Our results provide evidence that the rIFG is involved in pain-related empathy processing, which yields insights into how the brain perceives pain in others.

Frontotemporal dementia, music perception and social cognition share neurobiological circuits: A meta-analysis

Frontotemporal dementia (FTD) is a neurodegenerative disease that presents with profound changes in social cognition. Music might be a sensitive probe for social cognition abilities, but underlying neurobiological substrates are unclear. We performed a meta-analysis of voxel-based morphometry studies in FTD patients and functional MRI studies for music perception and social cognition tasks in cognitively normal controls to identify robust patterns of atrophy (FTD) or activation (music perception or social cognition). Conjunction analyses were performed to identify overlapping brain regions. In total 303 articles were included: 53 for FTD (n = 1153 patients, 42.5% female; 1337 controls, 53.8% female), 28 for music perception (n = 540, 51.8% female) and 222 for social cognition in controls (n = 5664, 50.2% female). We observed considerable overlap in atrophy patterns associated with FTD, and functional activation associated with music perception and social cognition, mostly encompassing the ventral language network. We further observed overlap across all three modalities in mesolimbic, basal forebrain and striatal regions. The results of our meta-analysis suggest that music perception and social cognition share neurobiological circuits that are affected in FTD. This supports the idea that music might be a sensitive probe for social cognition abilities with implications for diagnosis and monitoring.

Pharmacological fMRI provides evidence for opioidergic modulation of discrimination of facial pain expressions

The endogenous opioid system is strongly involved in the modulation of pain. However, the potential role of this system in perceiving painful facial expressions from others has not been sufficiently explored as of yet. To elucidate the contribution of the opioid system to the perception of painful facial expressions, we conducted a double‐blind, within‐subjects pharmacological functional magnetic resonance imaging (fMRI) study, in which 42 participants engaged in an emotion discrimination task (pain vs. disgust expressions) in two experimental sessions, receiving either the opioid receptor antagonist naltrexone or an inert substance (placebo). On the behavioral level, participants less frequently judged an expression as pain under naltrexone as compared to placebo. On the neural level, parametric modulation of activation in the (putative) right fusiform face area (FFA), which was correlated with increased pain intensity, was higher under naltrexone than placebo. Regression analyses revealed that brain activity in the right FFA significantly predicted behavioral performance in disambiguating pain from disgust, both under naltrexone and placebo. These findings suggest that reducing opioid system activity decreased participants' sensitivity for facial expressions of pain, and that this was linked to possibly compensatory engagement of processes related to visual perception, rather than to higher level affective processes, and pain regulation.

The behavioral and neural findings of this psychopharmacological fMRI study shed light on a causal role of the opioid system in the discrimination of painful facial expressions, paving the way for further exploration of clinical implications in the domains of pain diagnosis and treatment, on the one hand, and future research on the relationship between basic socio‐perceptual processing and empathy, on the other.

Empathic pain evoked by sensory and emotional-communicative cues share common and process-specific neural representations

Pain empathy can be evoked by multiple cues, particularly observation of acute pain inflictions or facial expressions of pain. Previous studies suggest that these cues commonly activate the insula and anterior cingulate, yet vicarious pain encompasses pain-specific responses as well as unspecific processes (e.g. arousal) and overlapping activations are not sufficient to determine process-specific shared neural representations. We employed multivariate pattern analyses to fMRI data acquired during observation of noxious stimulation of body limbs (NS) and painful facial expressions (FE) and found spatially and functionally similar cross-modality (NS versus FE) whole-brain vicarious pain-predictive patterns. Further analyses consistently identified shared neural representations in the bilateral mid-insula. The vicarious pain patterns were not sensitive to respond to non-painful high-arousal negative stimuli but predicted self-experienced thermal pain. Finally, a domain-general vicarious pain pattern predictive of self-experienced pain but not arousal was developed. Our findings demonstrate shared pain-associated neural representations of vicarious pain.

Differences between empathy for face and body pain: Cognitive and neural responses

Empathy for pain is a hotspot in the field of empathy research because of its specific cognitive and neural mechanism. Currently, studies of empathy for pain can be classified into two categories based on the body regions receiving the painful stimulus, i.e., empathy for face pain and empathy for body pain, which conveys painful information based on individuals’ faces or body parts, respectively. Although the existing evidence revealed differences between these two kinds of pain empathy regarding the underlying cognitive and neural mechanisms, the current studies tend to confuse these findings. Therefore, we summarized the differences between empathy for face and body pain, mainly regarding the behavioral reactivity tendency, brain activations, and electrophysiological (EEG) signals. These differences probably stem from the fact that the human face contains more emotional information, while other body parts contain more perceptual information. Thus, future studies should identify the distinctions between empathy for face and body pain, to explore further how empathy for face pain is affected by the facial information of others and focus on empathy for face pain in individuals with psychopathological disorders. Furthermore, the specific reasons for these distinctions and their underlying neuromechanisms deserve to be further reviewed.

Linking brain structure and activation in anterior insula cortex to explain the trait empathy for pain

The ability to perceive, understand, and react to the feelings of others' pain is referred to as empathy for pain which is composed of two components, affective‐perceptual empathy and cognitive‐evaluative empathy. Recent reviews on the neural mechanisms of empathetic pain showed the anterior insula (AI) cortex as a core circuit for empathy. However, little is known about the modulation of brain anatomy and empathic responses by trait measures of empathy (trait empathy). Thus, we investigated whether individual variation in the personality trait of empathy is associated with individual variation in the structure of specific brain regions using voxel‐based morphometry (VBM). We further investigated the relationship between the trait empathy and the activity of the same regions using state measures of empathy for pain in a trial‐by‐trial fashion in the given situation. VBM analysis indicated a small but significant negative relationship between trait empathy and gray matter volume in the bilateral AI. Functional MRI study further demonstrated that experimentally induced activity of the bilateral AI during state empathy for pain was also correlated with trait empathy. An asymmetry exists between the right and left AI between the affective and cognitive empathy. The right AI was found to be involved in the affective‐perceptual form of empathy and the left AI was active in cognitive‐evaluative forms of empathy. The interindividual differences in trait empathy may be reflected both in the state empathy and more stable brain structure difference.

The Role of Sensorimotor Processes in Pain Empathy

Pain is a salient, aversive sensation which motivates avoidance, but also has a strong social signaling function. Numerous studies have shown that regions of the nervous system active in association with first-hand pain are also active in response to the pain of others. When witnessing somatic pain, such as seeing bodies in painful situations, significant activations occur not only in areas related to the processing of negative emotions, but also in neuronal structures engaged in somatosensation and the control of skeletal muscles. These empathy-related sensorimotor activations are selectively reviewed in this article, with a focus on studies using electrophysiological methods and paradigms investigating responses to somatic pain. Convergent evidence from these studies shows that these activations (1) occur at multiple levels of the nervous system, from the spinal cord up to the cerebral cortex, (2) are best conceptualized as activations of a defensive system, in line with the role of pain to protect body from injury, and (3) contribute to establishing a matching of psychological states between the sufferer and the observer, which ultimately supports empathic understanding and motivate prosocial action. Future research should thus focus on how these sensorimotor responses are related to higher-order empathic responses, including affective sharing and emotion regulation, and how this motivates approach-related prosocial behaviors aimed at alleviating the pain and suffering of others.

A meta-analysis of neuroimaging studies on pain empathy: investigating the role of visual information and observers' perspective

Empathy relies on brain systems that support the interaction between an observer's mental state and cues about the others' experience. Beyond the core brain areas typically activated in pain empathy studies (insular and anterior cingulate cortices), the diversity of paradigms used may reveal secondary networks that subserve other more specific processes. A coordinate-based meta-analysis of fMRI experiments on pain empathy was conducted to obtain activation likelihood estimates along three factors and seven conditions: visual cues (body parts, facial expressions), visuospatial (first-person, thirdperson), and cognitive (self-, stimuli-, other-oriented tasks) perspectives. The core network was found across cues and perspectives, and common activation was observed in higher-order visual areas. Body-parts distinctly activated areas related with sensorimotor processing (superior and inferior parietal lobules, anterior insula) while facial expression distinctly involved the inferior frontal gyrus. Self- compared to other-perspective produced distinct activations in the left insula while stimulus- versus other-perspective produced distinctive responses in the inferior frontal and parietal lobules, precentral gyrus, and cerebellum. Pain empathy relies on a core network which is modulated by several secondary networks. The involvement of the latter seems to depend on the visual cues available and the observer's mental state that can be influenced by specific instructions.

Strategy-dependent modulation of cortical pain circuits for the attenuation of pain

The effectiveness of cognitive strategies to attenuate pain has been reported in various behavioural studies, however the underlying neuronal mechanisms are only now beginning to be understood. Using a 7 T fMRI, we investigated three different pain attenuation strategies in 20 healthy subjects via: (a) non-imaginal distraction by counting backwards in steps of seven; (b) imaginal distraction by imagining a safe place; and (c) reinterpretation of the pain valence (reappraisal). Although we found considerable variability in the performances, all strategies exhibited a significant relief of pain compared to an unmodulated pain condition. Our finding argues against a subject's potential predisposition for a certain attenuation approach, as some of the subjects performed well on all attenuation tasks yet others performed low on all attenuation tasks. We further investigated the variability of performance within-subjects and explored the cortical regions that contribute to successful single attempts of pain attenuation at trial level. For each of the three tasks, we found a different pattern of brain activity that reflects the performance of pain attenuation. The more successful trials are related to reduced activity of different parts of the insular cortex. Behavioural data suggest that distraction is the preferable cognitive strategy to modulate pain perception. For three different cognitive strategies we revealed brain regions that are suggested to reliably modulate the perception of pain. The findings could be of utmost benefit for future attempts to integrate neuroscientific techniques into the treatment of pain. Further studies are necessary to investigate whether the present results are transferable to patients as an essential part of the multimodal therapy for chronic pain. These patients may also benefit from additional neurofeedback techniques by combining the strategies with the cortical feedback in order to modulate pain-related brain activity.

Brain pathways of pain empathy activated by pained facial expressions: a meta-analysis of fMRI using the activation likelihood estimation method

OBJECTIVE:

The objective of this study is to summarize and analyze the brain signal patterns of empathy for pain caused by facial expressions of pain utilizing activation likelihood estimation, a meta-analysis method.

DATA SOURCES:

Studies concerning the brain mechanism were searched from the Science Citation Index, Science Direct, PubMed, DeepDyve, Cochrane Library, SinoMed, Wanfang, VIP, China National Knowledge Infrastructure, and other databases, such as SpringerLink, AMA, Science Online, Wiley Online, were collected. A time limitation of up to 13 December 2016 was applied to this study.

DATA SELECTION:

Studies presenting with all of the following criteria were considered for study inclusion: Use of functional magnetic resonance imaging, neutral and pained facial expression stimuli, involvement of adult healthy human participants over 18 years of age, whose empathy ability showed no difference from the healthy adult, a painless basic state, results presented in Talairach or Montreal Neurological Institute coordinates, multiple studies by the same team as long as they used different raw data.

OUTCOME MEASURES:

Activation likelihood estimation was used to calculate the combined main activated brain regions under the stimulation of pained facial expression.

RESULTS:

Eight studies were included, containing 178 subjects. Meta-analysis results suggested that the anterior cingulate cortex (BA32), anterior central gyrus (BA44), fusiform gyrus, and insula (BA13) were activated positively as major brain areas under the stimulation of pained facial expression.

CONCLUSION:

Our study shows that pained facial expression alone, without viewing of painful stimuli, activated brain regions related to pain empathy, further contributing to revealing the brain’s mechanisms of pain empathy.

Meta-analysis of ERP investigations of pain empathy underlines methodological issues in ERP research

Empathy has received considerable attention from the field of cognitive and social neuroscience. A significant portion of these studies used the event-related potential (ERP) technique to study the mechanisms of empathy for pain in others in different conditions and clinical populations. These show that specific ERP components measured during the observation of pain in others are modulated by several factors and altered in clinical populations. However, issues present in this literature such as analytical flexibility and lack of type 1 error control raise doubts regarding the validity and reliability of these conclusions. The current study compiled the results and methodological characteristics of 40 studies using ERP to study empathy of pain in others. The results of the meta-analysis suggest that the centro-parietal P3 and late positive potential component are sensitive to the observation of pain in others, while the early N1 and N2 components are not reliably associated with vicarious pain observation. The review of the methodological characteristics shows that the presence of selective reporting, analytical flexibility and lack of type 1 error control compromise the interpretation of these results. The implication of these results for the study of empathy and potential solutions to improve future investigations are discussed.

Influence of anxiety and alexithymia on brain activations associated with the perception of others' pain in autism

The circumstances under which empathy is altered in ASD remain unclear, as previous studies did not systematically find differences in brain activation between ASD and controls in empathy-eliciting paradigms, and did not always monitor whether differences were primarily due to ASD "per se", or to conditions overlapping with ASD, such as alexithymia and anxiety. Here, we collected fMRI data from 47 participants (22 ASD) viewing pictures depicting hands and feet of unknown others in painful, disgusting, or neutral situations. We computed brain activity for painful and disgusting stimuli (vs. neutral) in whole brain and in regions of interest among the brain areas typically activated during the perception of nociceptive stimuli. Group differences in brain activation disappeared when either alexithymia or anxiety - both elevated in the ASD group - were controlled for. Regression analyses indicated that the influence of symptoms was mainly shared between autistic symptomatology, alexithymia and anxiety or driven by unique contributions from alexithymia or anxiety. Our results suggest that affective empathy may be affected in ASD, but that this association is complex. The respective contribution of alexithymia and anxiety to decreased affective empathy of people with ASD may be due to the association of those psychiatric conditions with reduced motor resonance/Theory of Mind.

Neural correlates of prosocial behavior towards persons in pain in healthcare providers

Pain perceived in others can be a stressful signal that elicits personal distress and discomfort that can interfere with prosocial behaviors. Healthcare providers (HCPs) have to be able to regulate these self-oriented feelings to offer optimal help to patients in pain. However, previous studies have documented a tendency in HCPs to underestimate the pain of patients that could interfere with optimal help to these patients. The aim of this study was to compare HCP and control (CTL) participants' prosocial behavior towards persons in pain and their associated brain responses. HCPs and CTL participants took part in a newly developed prosocial task during which they were asked to choose how much time they wanted to offer to help patients in pain. It was shown that compared to CTL participants, HCPs offered more help to persons in pain and reported less trait personal distress when facing suffering in others. Additional evidence was provided by the fMRI results, which indicated that compared to CTL participants, HCP participants showed different pattern of activity in the dorsolateral prefrontal cortex, bilateral precuneus and the posterior cingulate cortex during the prosocial task, suggesting that the underlying mechanisms of the difference in prosocial behaviors could vary according to the degree to which processes such as mentalizing and cognitive control are solicited.

Empathy in paediatric intensive care nurses part 2: Neural correlates

AIMS

To determine if there are brain activity differences between paediatric intensive care nurses and allied health professionals during pain intensity rating tasks and test whether these differences are related to the population observed (infant or adult) and professional experience.

BACKGROUND

The underestimation of patients' pain by healthcare professionals has generally been associated with patterns of change in neural response to vicarious pain, notably reduced activation in regions associated with affective sharing and increased activation in regions associated with regulation, compared with controls. Paediatric nurses, however, have recently been found to provide higher estimates of infants' pain in comparison to allied health controls, suggesting that changes in neural response of this population might be different than other health professionals.

DESIGN

Cross-sectional study.

METHODS

Functional MRI data were acquired from September 2014-June 2015 and used to compare changes in brain activity in 27 female paediatric care nurses and 24 allied health professionals while rating the pain of infants and adults in a series of video clips.

RESULTS

Paediatric nurses rated infant and adult pain higher than allied health professionals, but the two groups' neural response only differed during observation of infant pain; paediatric nurses mainly showed significantly less activation in the medial prefrontal cortex (linked to cognitive empathy) and in the left anterior insula and inferior frontal cortex (linked to affective sharing).

CONCLUSIONS

Patterns of neural activity to vicarious pain may vary across healthcare professions and patient populations and the amount of professional experience might explain part of these differences.

Responses to others' pain in adults with autistic traits: The influence of gender and stimuli modality

Individuals with autism-spectrum disorder (ASD) exhibit impairments in response to others’ pain. Evidence suggests that features of autism are not restricted to individuals with ASD, and that autistic traits vary throughout the general population. To investigate the association between autistic traits and the responses to others’ pain in typically developing adults, we employed the Autism-Spectrum Quotient (AQ) to quantify autistic traits in a group of 1670 healthy adults and explored whether 60 participants (30 males and 30 females) with 10% highest AQ scores (High-AQ) would exhibit difficulties in the responses to others’ pain relative to 60 participants (30 males and 30 females) with 10% lowest AQ scores (Low-AQ). This study included a Visual Task and an Auditory Task to test behavioral differences between High-AQ and Low-AQ groups’ responses to others’ pain in both modalities. For the Visual Task, participants were instructed to respond to pictures depicting others’ pain. They were instructed to judge the stimuli type (painful or not), judge others’ pain intensity, and indicate the unpleasantness they personally felt. For the Auditory Task, experimental procedures were identical to the Visual Task except that painful voices were added. Results showed the High-AQ group was less accurate than the Low-AQ group in judging others’ pain. Moreover, relative to Low-AQ males, High-AQ males had significantly longer reaction times in judging others’ pain in the Auditory Task. However, High-AQ and Low-AQ females showed similar reaction times in both tasks. These findings demonstrated identification of others’ pain by healthy adults is related to the extent of autistic traits, gender, and modality.

Triggering Descending Pain Inhibition by Observing Ourselves or a Loved-One in Pain

OBJECTIVES

Recent studies demonstrate that empathy-evoked brain responses include the activation of brainstem structures responsible for triggering descending pain inhibition. Unfortunately, direct evidence linking empathy for pain and descending inhibitory controls (conditioned pain modulation) is lacking. This study, therefore, aimed to determine if the observation of ourselves or a loved-one in pain could activate descending pain inhibition without exposure to a noxious stimulation; which is otherwise required.

METHODS

Descending pain inhibition was triggered by immersing the right arm of participants (15 heterosexual couples; mean age±SE: 28.89±2.14) in a bath of cold water. The effects of empathy on descending pain inhibition were observed by immersing the right arm of participants in a bath of lukewarm water while having them watch a video of either themselves or their spouse during a previous nociceptive immersion. Immersion of the arm in a bath of lukewarm water without empathic (video) observation was also included as a control condition.

RESULTS

A strong inhibitory response activated by the mere observation of the video of themselves or their spouse in pain without a nociceptive conditioning stimulus. Associative statistics also showed that strong pain catastrophizing responses while watching the video resulted in stronger pain inhibition. Moreover, high levels of empathy were associated with stronger pain inhibition, but only for women.

DISCUSSION

This study showed that observing someone in pain triggers descending pain inhibition. Results also demonstrate how empathy and gender are affecting pain modulation mechanisms.

Detection of central circuits implicated in the formation of novel pain memories

Being able to remember physically and emotionally painful events in one's own past may shape behavior, and can create an aversion to a variety of situations. Pain imagination is a related process that may include recall of past experiences, in addition to production of sensory and emotional percepts without external stimuli. This study aimed to understand 1) the central nervous system processes that underlie pain imagination, 2) the retrieval of pain memories, and 3) to compare the latter with visual object memory. These goals were achieved by longitudinally investigating brain function with functional magnetic resonance imaging in a unique group of healthy volunteers who had never experienced tooth pain. In these subjects, we compared brain responses elicited during three experimental conditions in the following order: imagination of tooth pain (pain imagination), remembering one's own house (object memory), and remembrance of tooth pain following an episode of induced acute tooth pain (pain memory). Key observations stemming from group-level conjunction analyses revealed common activation in the posterior parietal cortex for both pain imagination and pain memory, while object and pain memory each had strong activation predominantly within the middle frontal gyrus. When contrasting pain imagination and memory, significant activation differences were observed in subcortical structures (ie, parahippocampus - pain imagination > pain memory; midbrain - pain memory > pain imagination). Importantly, these findings were observed in the presence of consistent and reproducible psychophysical and behavioral measures that informed on the subjects' ability to imagine novel and familiar thoughts, as well as the subjects' pain perception.

The Perception and Estimation of Others' Pain according to Children

Accurate interpretation of pain expressed by others is important for socialization; however, the development of this skill in children is still poorly understood. Empathy for pain models propose two main components (affective and cognitive), which develop at different stages of life. The study's objective was to investigate the children's ability between 3 and 12 years of age to detect and assess the pain intensity in others using visual stimuli depicting either facial expressions of pain or hands in painful contexts. 40 preschool children and 62 school-aged children were recruited. Children observed series of stimuli and evaluated the pain intensity depicted. Results demonstrated that children as young as three years old were able to detect and assess pain in both types of stimuli and this ability continued to improve until the age of 12. Participants demonstrated better detection performance with hands than with faces. Results were coherent with the idea that the two types of stimuli presented recruit different processes. Pain detection in hands appears to rely mostly on affective sharing processes that are effective early in life, while older children's higher ability to perceive pain in facial expressions suggests that this ability is associated with the gradual development of cognitive processes.

The role of spatial frequency information in the recognition of facial expressions of pain

Being able to detect pain from facial expressions is critical for pain communication. Alongside identifying the specific facial codes used in pain recognition, there are other types of more basic perceptual features, such as spatial frequency (SF), which refers to the amount of detail in a visual display. Low SF carries coarse information, which can be seen from a distance, and high SF carries fine-detailed information that can only be perceived when viewed close up. As this type of basic information has not been considered in the recognition of pain, we therefore investigated the role of low-SF and high-SF information in the decoding of facial expressions of pain. Sixty-four pain-free adults completed 2 independent tasks: a multiple expression identification task of pain and core emotional expressions and a dual expression "either-or" task (pain vs fear, pain vs happiness). Although both low-SF and high-SF information make the recognition of pain expressions possible, low-SF information seemed to play a more prominent role. This general low-SF bias would seem an advantageous way of potential threat detection, as facial displays will be degraded if viewed from a distance or in peripheral vision. One exception was found, however, in the "pain-fear" task, where responses were not affected by SF type. Together, this not only indicates a flexible role for SF information that depends on task parameters (goal context) but also suggests that in challenging visual conditions, we perceive an overall affective quality of pain expressions rather than detailed facial features.

Feeling the burn: When it looks like it hurts, and belongs to me, it really does hurt more

We examined changes in pain sensitivity in the rubber hand illusion (RHI). Experiment 1 investigated changes in pain tolerance immediately after a "healthy" and "wounded" RHI when immersing the hand in a cold pressor ice bath. There was 19% increased pain tolerance and increased perception detection threshold after the healthy RHI, but 11% reduction after the wounded RHI. Experiment 2 examined pain experience during the wounded RHI with capsaicin-induced hyperalgesia. Pain intensity and unpleasantness was higher on the illusion arm during the synchronous RHI, compared with asynchronous trials. There was no change in pain experience on the control arm, and both arms had similar pain sensitivity after the experiment. Our results highlight the impact of embodying a substitute limb on pain, with increased tolerance and reduced tactile sensitivity when the fake limb is healthy and apparently pain-free, but increased pain sensitivity when the self-attributed limb appears to be wounded.

Sub-optimal presentation of painful facial expressions enhances readiness for action and pain perception following electrocutaneous stimulation

Observation of others’ painful facial expressions has been shown to facilitate behavioral response tendencies and to increase pain perception in the observer. However, in previous studies, expressions were clearly visible to the observer and none of those studies investigated the effect of presence of peripheral stimulation on response tendencies. This study focuses on the effect of sub-optimal presentation of painful facial expressions in the presence and absence of an electrocutaneous stimulus. Twenty-two healthy individuals categorized arrow targets which were preceded by a sub-optimally presented facial expression (painful, happy, or neutral in different blocks). On half of the trials, aversive electrocutaneous stimulation was delivered to the wrist of the non-dominant hand between the presentation of facial expression and target (an arrow directing to right or left). Participants’ task was to indicate direction of the arrow as soon as it appears on the screen by pressing the corresponding key on the keyboard and to rate their pain at the end of block. Analysis showed that responses were faster to targets preceded by aversive stimulation than to targets not preceded by stimulation, especially following painful expressions. Painfulness ratings were higher following painful expressions than following happy expressions. These findings suggest that sub-optimally presented painful expressions can enhance readiness to act to neutral, non-pain-related targets after aversive stimulation and can increase pain perception.

The role of cingulate cortex in vicarious pain

Vicarious pain is defined as the observation of individuals in pain. There is growing neuroimaging evidence suggesting that the cingulate cortex plays a significant role in self-experienced pain processing. Yet, very few studies have directly tested the distinct functions of the cingulate cortex for vicarious pain. In this review, one EEG and eighteen neuroimaging studies reporting cingulate cortex activity during pain observation were discussed. The data indicate that there is overlapping neural activity in the cingulate cortex during self- and vicarious pain. Such activity may contribute to shared neural pain representations that permit inference of the affective state of individuals in pain, facilitating empathy. However, the exact location of neuronal populations in which activity overlaps or differs for self- and observed pain processing requires further confirmation. This review also discusses evidence suggesting differential functions of the cingulate cortex in cognitive, affective, and motor processing during empathy induction. While affective processing in the cingulate cortex during pain observation has been explored relatively more often, its attention and motor roles remain underresearched. Shedding light on the neural correlates of vicarious pain and corresponding empathy in healthy populations can provide neurobiological markers and intervention targets for empathic deficits found in various clinical disorders.

Mirroring pain in the brain: emotional expression versus motor imitation

Perception of pain in others via facial expressions has been shown to involve brain areas responsive to self-pain, biological motion, as well as both performed and observed motor actions. Here, we investigated the involvement of these different regions during emotional and motor mirroring of pain expressions using a two-task paradigm, and including both observation and execution of the expressions. BOLD responses were measured as subjects watched video clips showing different intensities of pain expression and, after a variable delay, either expressed the amount of pain they perceived in the clips (pain task), or imitated the facial movements (movement task). In the pain task condition, pain coding involved overlapping activation across observation and execution in the anterior cingulate cortex, supplementary motor area, inferior frontal gyrus/anterior insula, and the inferior parietal lobule, and a pain-related increase (pain vs. neutral) in the anterior cingulate cortex/supplementary motor area, the right inferior frontal gyrus, and the postcentral gyrus. The ‘mirroring’ response was stronger in the inferior frontal gyrus and middle temporal gyrus/superior temporal sulcus during the pain task, and stronger in the inferior parietal lobule in the movement task. These results strongly suggest that while motor mirroring may contribute to the perception of pain expressions in others, interpreting these expressions in terms of pain content draws more heavily on networks involved in the perception of affective meaning.

The sensory profile of children with asthma

AIM

Sensory hypersensitivity is one expression of sensory processing disorders (SPD) and results from the inability to regulate an appropriate response to a sensory input in an adaptive manner. We explored the sensory processing profile of children with asthma, based on reports from parents.

METHODS

We studied 86 children between the ages of four and 11 years: 37 diagnosed with asthma and 49 healthy controls. The parents of all participants filled out the Short Sensory Profile (SSP) that measures the child's behavioural reactions to sensory stimuli in daily environments.

RESULTS

Sensory processing disorders were more prevalent among children with asthma (F7,71 = 4.16, p = 0.001; ή(2) = 0.29) than among healthy controls and were mainly reflected by hypersensitivity. While about 90% of the healthy children were reported to actively seek sensory stimuli, only 53% of the asthmatic children showed this trend. In the study group, 25.7% of the children's scores reflected abnormal sensory performance, compared with 0% of the controls (χ(2) =21.93; p < 0.001).

CONCLUSION

Children with asthma may suffer from SPD. Our finding supports previous reports that suggest that the central nervous system is involved in the pathogenesis of atopic conditions. The sensory profile of children with asthma should be evaluated and treated as required.

Mutual influences of pain and emotional face processing

The perception of unpleasant stimuli enhances whereas the perception of pleasant stimuli decreases pain perception. In contrast, the effects of pain on the processing of emotional stimuli are much less known. Especially given the recent interest in facial expressions of pain as a special category of emotional stimuli, a main topic in this research line is the mutual influence of pain and facial expression processing. Therefore, in this mini-review we selectively summarize research on the effects of emotional stimuli on pain, but more extensively turn to the opposite direction namely how pain influences concurrent processing of affective stimuli such as facial expressions. Based on the motivational priming theory one may hypothesize that the perception of pain enhances the processing of unpleasant stimuli and decreases the processing of pleasant stimuli. This review reveals that the literature is only partly consistent with this assumption: pain reduces the processing of pleasant pictures and happy facial expressions, but does not - or only partly - affect processing of unpleasant pictures. However, it was demonstrated that pain selectively enhances the processing of facial expressions if these are pain-related (i.e., facial expressions of pain). Extending a mere affective modulation theory, the latter results suggest pain-specific effects which may be explained by the perception-action model of empathy. Together, these results underscore the important mutual influence of pain and emotional face processing.

Attention effects on vicarious modulation of nociception and pain

The observation of others' facial expressions of pain has been shown to facilitate the observer's nociceptive responses and to increase pain perception. We investigated how this vicarious facilitation effect is modulated by directing the observer's attention toward the meaning of pain expression or the facial movements. In separate trials, participants were instructed to assess the "intensity of the pain expression"(meaning) or to "discriminate the facial movements" in the upper vs lower part of the face shown in 1-second dynamic clips displaying mild, moderate, or strong pain expressions or a neutral control. In 50% of the trials, participants received a painful electrical stimulation to the sural nerve immediately after the presentation of the expression. Low-level nociceptive reactivity was measured with the RIII-response, and pain perception was assessed using pain ratings. Pain induced by the electrical stimulation increased after viewing stronger pain expressions in both tasks, but the RIII-response showed this vicarious facilitation effect only in the movement discrimination task at the strongest expression intensity. These findings are consistent with the notion that vicarious processes facilitate self-pain and may prime automatic nociceptive responses. However, this priming effect is influenced by top-down attentional processes. These results provide another case of dissociation between reflexive and perceptual processes, consistent with the involvement of partly separate brain networks in the regulation of cortical and lower-level nociceptive responses. Combined with previous results, these findings suggest that vicarious pain facilitation is an automatic process that may be diminished by top-down attentional processes directed at the meaning of the expression.

Emotional contagion for pain is intact in autism spectrum disorders

Perceiving others in pain generally leads to empathic concern, consisting of both emotional and cognitive processes. Empathy deficits have been considered as an element contributing to social difficulties in individuals with autism spectrum disorders (ASD). Here, we used functional magnetic resonance imaging and short video clips of facial expressions of people experiencing pain to examine the neural substrates underlying the spontaneous empathic response to pain in autism. Thirty-eight adolescents and adults of normal intelligence diagnosed with ASD and 35 matched controls participated in the study. In contrast to general assumptions, we found no significant differences in brain activation between ASD individuals and controls during the perception of pain experienced by others. Both groups showed similar levels of activation in areas associated with pain sharing, evidencing the presence of emotional empathy and emotional contagion in participants with autism as well as in controls. Differences between groups could be observed at a more liberal statistical threshold, and revealed increased activations in areas involved in cognitive reappraisal in ASD participants compared with controls. Scores of emotional empathy were positively correlated with brain activation in areas involved in embodiment of pain in ASD group only. Our findings show that simulation mechanisms involved in emotional empathy are preserved in high-functioning individuals with autism, and suggest that increased reappraisal may have a role in their apparent lack of caring behavior.

Racial bias in neural empathic responses to pain

Recent studies have shown that perceiving the pain of others activates brain regions in the observer associated with both somatosensory and affective-motivational aspects of pain, principally involving regions of the anterior cingulate and anterior insula cortex. The degree of these empathic neural responses is modulated by racial bias, such that stronger neural activation is elicited by observing pain in people of the same racial group compared with people of another racial group. The aim of the present study was to examine whether a more general social group category, other than race, could similarly modulate neural empathic responses and perhaps account for the apparent racial bias reported in previous studies. Using a minimal group paradigm, we assigned participants to one of two mixed-race teams. We use the term race to refer to the Chinese or Caucasian appearance of faces and whether the ethnic group represented was the same or different from the appearance of the participant' own face. Using fMRI, we measured neural empathic responses as participants observed members of their own group or other group, and members of their own race or other race, receiving either painful or non-painful touch. Participants showed clear group biases, with no significant effect of race, on behavioral measures of implicit (affective priming) and explicit group identification. Neural responses to observed pain in the anterior cingulate cortex, insula cortex, and somatosensory areas showed significantly greater activation when observing pain in own-race compared with other-race individuals, with no significant effect of minimal groups. These results suggest that racial bias in neural empathic responses is not influenced by minimal forms of group categorization, despite the clear association participants showed with in-group more than out-group members. We suggest that race may be an automatic and unconscious mechanism that drives the initial neural responses to observed pain in others.

Weighing the stigma of weight: An fMRI study of neural reactivity to the pain of obese individuals

Explicit negative attitudes and blameful beliefs (e.g. poor diet, laziness) towards obese individuals are well documented and are pervasive even among health professionals. Here we sought to determine whether obesity stigma is reflected in a fundamental feature of intersubjectivity namely the automatic neural resonance with others' affective experiences. During fMRI, normal-weight female participants observed short clips depicting normal-weight (NW) and obese (Ob) models experiencing pain. Importantly, participants believed that half of the Ob were overweight due to a hormonal disorder (HormOb) and ignored the cause of obesity of the remaining models (Unknown obese models; UnkOb). Analyses of hemodynamic responses showed reduced activity to the pain of Ob compared to that of NW in areas associated with pain processing and early visual processing. The comparison between the two Ob conditions revealed a further decrease of activity to HormOb's pain compared to UnkOb's (and NW) pain in the right inferior frontal gyrus, an area associated with emotional resonance. Our study demonstrates that stigma for obese individuals can be observed at implicit levels, and that it is modulated by knowledge concerning the etiology of obesity, with the seemingly surprising result that obesity due to disease may result in greater stigmatization. Moreover, the perceived similarity with the models and the ambivalent emotion of pity may index biased brain responses to obese individuals' pain. The study highlights a possibly important neural link between resonance with the pain of others and obesity stigma.

The modulation of somatosensory resonance by psychopathic traits and empathy

A large number of neuroimaging studies have shown neural overlaps between first-hand experiences of pain and the perception of pain in others. This shared neural representation of vicarious pain is thought to involve both affective and sensorimotor systems. A number of individual factors are thought to modulate the cerebral response to other's pain. The goal of this study was to investigate the impact of psychopathic traits on the relation between sensorimotor resonance to other's pain and self-reported empathy. Our group has previously shown that a steady-state response to non-painful stimulation is modulated by the observation of other people's bodily pain. This change in somatosensory response was interpreted as a form of somatosensory gating (SG). Here, using the same technique, SG was compared between two groups of 15 young adult males: one scoring very high on a self-reported measure of psychopathic traits [60.8 ± 4.98; Levenson's Self-Report Psychopathy Scale (LSRP)] and one scoring very low (42.7 ± 2.94). The results showed a significantly greater reduction of SG to pain observation for the high psychopathic traits group compared to the low psychopathic traits group. SG to pain observation was positively correlated with affective and interpersonal facet of psychopathy in the whole sample. The high psychopathic traits group also reported lower empathic concern (EC) scores than the low psychopathic traits group. Importantly, primary psychopathy, as assessed by the LSRP, mediated the relation between EC and SG to pain observation. Together, these results suggest that increase somatosensory resonance to other's pain is not exclusively explained by trait empathy and may be linked to other personality dimensions, such as psychopathic traits.

Acute stress contributes to individual differences in pain and pain-related brain activity in healthy and chronic pain patients

Individual differences in pain sensitivity and reactivity are well recognized but the underlying mechanisms are likely to be diverse. The phenomenon of stress-induced analgesia is well documented in animal research and individual variability in the stress response in humans may produce corresponding changes in pain. We assessed the magnitude of the acute stress response of 16 chronic back pain (CBP) patients and 18 healthy individuals exposed to noxious thermal stimulations administered in a functional magnetic resonance imaging experiment and tested its possible contribution to individual differences in pain perception. The temperature of the noxious stimulations was determined individually to control for differences in pain sensitivity. The two groups showed similar significant increases in reactive cortisol across the scanning session when compared with their basal levels collected over 7 consecutive days, suggesting normal hypothalamic-pituitary-adrenal axis reactivity to painful stressors in CBP patients. Critically, after controlling for any effect of group and stimulus temperature, individuals with stronger cortisol responses reported less pain unpleasantness and showed reduced blood oxygenation level-dependent activation in nucleus accumbens at the stimulus onset and in the anterior mid-cingulate cortex (aMCC), the primary somatosensory cortex, and the posterior insula. Mediation analyses indicated that pain-related activity in the aMCC mediated the relationship between the reactive cortisol response and the pain unpleasantness. Psychophysiological interaction analysis further revealed that higher stress reactivity was associated with reduced functional connectivity between the aMCC and the brainstem. These findings suggest that acute stress modulates pain in humans and contributes to individual variability in pain affect and pain-related brain activity.