151 research outputs found

    Investigating the potential role of arousal in multisensory hypersensitivity

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    Recent studies have shown that experimentally induced long-lasting sensitization of nociceptive pathways in healthy human volunteers not only leads to the typically-observed hypersensitivity to mechanical pinprick stimuli, but also to an enhanced processing of non-nociceptive stimuli, as shown by amplitude increases in the cortical responses to visual and vibrotactile stimuli presented on a sensitized as compared to a non-sensitized body part. These latter effects have been hypothesized to share similarities with the hypersensitivity to a plethora of sensory stimuli that has been reported for some chronic pain conditions, such as fibromyalgia. However, to date, the mechanisms leading to such multisensory hypersensitivity remain unexplained, since they cannot be accounted for by the spinal mechanisms that increase pain perception after sensitization. We will present a study protocol that investigates whether increased arousal, triggered by the intense stimulation of the nociceptors, may be a potential underlying mechanism of both nociceptive and non-nociceptive hypersensitivity. In a between-subject design, we will use two different sensitization procedures (burst vs. continuous electrical stimulation applied on the arm during two minutes) in healthy participants and investigate 1) whether burst stimulation, which typically leads to higher nociceptive hypersensitivity, is also associated with higher arousal than continuous stimulation, by testing differences in mechanical pinprick sensitivity and arousal, measured as skin conductance level (SCL) before, during and after the sensitization, between the two procedures; 2) differences in somatosensory evoked potentials (SEPs) to vibrotactile stimuli on the sensitized vs. control arm; 3) the relationship between SCL and SEPs/mechanical pinprick sensitivity

    The Effect of High Versus Low Cognitive Load on the Development of Nociceptive Hypersensitivity: The Roles of Sympathetic Arousal, Sex, and Pain-Related Fear

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    BACKGROUND: According to limited-capacity theories of attention, less attentional resources remain available when engaging in a high versus a low demanding cognitive task. This may reduce the perceived intensity and the evoked cortical responses of concomitant nociceptive stimuli. Whether and how the competition for limited attentional resources between a cognitive task and pain impacts the development of long-lasting hypersensitivity is unclear. METHODS: Eighty-four healthy participants were randomized into a low or high cognitive load group. Low Frequency electrical Stimulation (LFS) of the skin was used to induce secondary hypersensitivity. We hypothesized that performing the high load task during LFS would reduce the development of hypersensitivity. We examined whether painfulness, non-pain-related sympathetic arousal, or sex related to hypersensitivity, by assessing intensity and unpleasantness of mechanical pinprick stimulation. During task execution, we recorded steady-state evoked potentials evoked by LFS, and skin conductance level for sympathetic arousal. Afterwards, participants reported task difficulty and LFS-related fear. For the primary outcomes, we used mixed ANOVAs. RESULTS: The results confirmed the difference in cognitive load. Although LFS successfully induced hypersensitivity, the high load task did not reduce its development. Next, the steady-state evoked potentials did not differ between groups. Hypersensitivity correlated positively with pain-related fear and negatively with skin conductance level before LFS, despite the lack of group differences in skin conductance level. We did not find any sex differences in hypersensitivity. CONCLUSIONS: These results do not confirm that high cognitive load or sex modulate hypersensitivity, but show associations with pain-related fear and non-pain-related sympathetic arousal

    The impact of the social context on the development of secondary hyperalgesia:an experimental study

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    Social support has been shown to reduce pain ratings and physiological responses to acute pain stimuli. Furthermore, this relationship is moderated by adult attachment styles. However, these effects have not been characterized in experimentally induced symptoms of chronic pain, such as secondary hyperalgesia (SH) which is characterized by an increased sensitivity of the skin surrounding an injury. We aimed to examine whether social support by handholding from a romantic partner can attenuate the development of experimentally induced SH. Thirty-seven women, along with their partners, participated in 2 experimental sessions 1 week apart. In both sessions, SH was induced using an electrical stimulation protocol. In the support condition, the partner was seated across from the participant holding the participant's hand during the electrical stimulation, whereas in the alone condition, the participant went through the stimulation alone. Heart rate variability was measured for both the participant as well as the partner before, during, and after the stimulation. We found that the width of the area of hyperalgesia was significantly smaller in the support condition. Attachment styles did not moderate this effect of social support on the area width. Increasing attachment avoidance was associated with both a smaller width of hyperalgesia and a smaller increase in the sensitivity on the stimulated arm. For the first time, we show that social support can attenuate the development of secondary hyperalgesia and that attachment avoidance may be associated with an attenuated development of secondary hyperalgesia

    Error Processing and Pain: A New Perspective

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    Errors put organisms in danger. Upon error commission, error processing allows for the updating of behavior that proved ineffective in light of the current context and goals, and for the activation of behavioral defensive systems. Pain, on the other hand, signals actual or potential danger to one's physical integrity and, likewise, motivates protective behavior. These parallels suggest the existence of cross-links between pain and error processing but so far their relationship remains elusive. In this review, we tie together findings from the field of pain research with those from electroencephalography studies on error processing [specifically the Error Related Negativity (ERN) and Positivity (Pe)]. More precisely, we discuss three plausible associations: Firstly, pain may enhance error processing as it increases error salience. Secondly, persons fearful of pain may be particularly vigilant towards painful errors and thus show a stronger neural response to them. Thirdly, the ERN as a component of the neural response to error commission is considered an endophenotype of threat sensitivity. As high sensitivity to pain threats is known to incite avoidance behavior, this raises the intriguing possibility that neural signatures of error processing predict pain-related protective behaviors, such as avoidance. We propose an integration of these findings into a common framework to inspire future research. Perspectives Inspired by research in anxiety disorders, we discuss the potential bi-directional relationships between error processing and pain, and identify future directions to examine the neural and psychological processes involved in acute and chronic pain and respective avoidance behavior

    Error Processing and Pain:A New Perspective

    No full text
    Errors put organisms in danger. Upon error commission, error processing allows for the updating of behavior that proved ineffective in light of the current context and goals, and for the activation of behavioral defensive systems. Pain, on the other hand, signals actual or potential danger to one's physical integrity and, likewise, motivates protective behavior. These parallels suggest the existence of cross-links between pain and error processing but so far their relationship remains elusive. In this review, we tie together findings from the field of pain research with those from electroencephalography studies on error processing [specifically the Error Related Negativity (ERN) and Positivity (Pe)]. More precisely, we discuss three plausible associations: Firstly, pain may enhance error processing as it increases error salience. Secondly, persons fearful of pain may be particularly vigilant towards painful errors and thus show a stronger neural response to them. Thirdly, the ERN as a component of the neural response to error commission is considered an endophenotype of threat sensitivity. As high sensitivity to pain threats is known to incite avoidance behavior, this raises the intriguing possibility that neural signatures of error processing predict pain-related protective behaviors, such as avoidance. We propose an integration of these findings into a common framework to inspire future research. Perspectives Inspired by research in anxiety disorders, we discuss the potential bi-directional relationships between error processing and pain, and identify future directions to examine the neural and psychological processes involved in acute and chronic pain and respective avoidance behavior

    Perceptual correlates of homosynaptic long-term potentiation in human nociceptive pathways: A replication study

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    Animal studies have shown that high-frequency stimulation (HFS) of peripheral C-fibres induces long-term potentiation (LTP) within spinal nociceptive pathways. The aim of this replication study was to assess if a perceptual correlate of LTP can be observed in humans. In 20 healthy volunteers, we applied HFS to the left or right volar forearm. Before and after applying HFS, we delivered single electrical test stimuli through the HFS electrode while a second electrode at the contra-lateral arm served as a control condition. Moreover, to test the efficacy of the HFS protocol, we quantified changes in mechanical pinprick sensitivity before and after HFS of the skin surrounding both electrodes. The perceived intensity was collected for both electrical and mechanical stimuli. After HFS, the perceived pain intensity elicited by the mechanical pinprick stimuli applied on the skin surrounding the HFS-treated site was significantly higher compared to control site (heterotopic effect). Furthermore, we found a higher perceived pain intensity for single electrical stimuli delivered to the HFS-treated site compared to the control site (homotopic effect). Whether the homotopic effect reflects a perceptual correlate of homosynaptic LTP remains to be elucidated.Fil: van de Broeke, Emanuel N.. Université Catholique de Louvain; BélgicaFil: Vanmaele, Tessa. Katholikie Universiteit Leuven; BélgicaFil: Mouraux, André. Université Catholique de Louvain; BélgicaFil: Stouffs, Alexandre. Université Catholique de Louvain; BélgicaFil: Biurrun Manresa, José Alberto. Universidad Nacional de Entre Ríos. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática; ArgentinaFil: Torta, Diana M.. Katholikie Universiteit Leuven; Bélgic

    Is it a painful error?: The effect of unpredictability and intensity of punishment on the error-related negativity, and somatosensory evoked potentials

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    We examined how predictable and unpredictable punishment intensity contingent on error commission modulated ERN amplitudes. We recorded the ERN in 35 healthy volunteers performing the Eriksen flanker task. Errors were punished with predictable nonpainful, painful or unpredictable electrical stimulation. Furthermore, we investigated trait anxiety. We observed that ERN amplitudes did not differ across conditions, nor were there significant effects of anxiety. In contrast, we found that predictable painful punishments led to smaller Error Positivity (Pe). The effects of predictability and intensity were present in Somatosensory Evoked Potentials elicited by the punishments. N1 amplitudes were increased for painful compared to nonpainful stimulation, and P2/P3 amplitudes for painful compared to nonpainful, and for unpredictable compared to predictable stimulation. We suggest that unpredictability and increased painfulness of punishments enhance the potential motivational significance of the errors, but do not potentiate ERN amplitudes beyond the ones elicited by errors punished with predictable nonpainful stimulation

    High-frequency electrical stimulation of cutaneous nociceptors differentially affects pain perception elicited by homotopic and heterotopic electrical stimuli.

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    Animal studies have shown that high-frequency electrical stimulation (HFS) of peripheral C-fiber nociceptors induces both homo- and heterosynaptic long-term potentiation (LTP) within spinal nociceptive pathways. In humans, when HFS is applied onto the skin to activate nociceptors, single electrical stimuli are perceived more intense at the HFS site compared to a control site, a finding that was interpreted as a perceptual correlate of homosynaptic LTP. The present study aimed to investigate if after HFS the pain elicited by electrical stimuli delivered at the skin next to the HFS site is perceived as more intense compared to the pain at a control site (contralateral arm). To test this, HFS was applied to one of the two ventral forearms of twenty-four healthy participants. Before and after HFS, single electrical stimuli were delivered through the HFS electrode, through an identical electrode next to the HFS electrode and through an identical electrode at the contralateral arm. After HFS, the pain elicited by the single electrical stimuli was reduced at all three sites, with the largest reduction at the HFS site. Nevertheless, electrical stimuli delivered to the skin next to the HFS site were perceived as more intense than control stimuli. This result indicates that higher pain ratings to electrical stimuli after HFS at the HFS site cannot solely be interpreted as a perceptual correlate of homosynaptic changes. Furthermore, we show for the first time, in humans, that HFS can reduce pain elicited by single electrical stimuli delivered through the same electrode

    Is it a painful error?:The effect of unpredictability and intensity of punishment on the error-related negativity, and somatosensory evoked potentials

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    We examined how predictable and unpredictable punishment intensity contingent on error commission modulated ERN amplitudes. We recorded the ERN in 35 healthy volunteers performing the Eriksen flanker task. Errors were punished with predictable nonpainful, painful or unpredictable electrical stimulation. Furthermore, we investigated trait anxiety. We observed that ERN amplitudes did not differ across conditions, nor were there significant effects of anxiety. In contrast, we found that predictable painful punishments led to smaller Error Positivity (Pe). The effects of predictability and intensity were present in Somatosensory Evoked Potentials elicited by the punishments. N1 amplitudes were increased for painful compared to nonpainful stimulation, and P2/P3 amplitudes for painful compared to nonpainful, and for unpredictable compared to predictable stimulation. We suggest that unpredictability and increased painfulness of punishments enhance the potential motivational significance of the errors, but do not potentiate ERN amplitudes beyond the ones elicited by errors punished with predictable nonpainful stimulation
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