Unpleasantness Ratings Research Articles

Integrated Meditation and Exercise Therapy: A Randomized Controlled Pilot of a Combined Nonpharmacological Intervention Focused on Reducing Disability and Pain in Patients with Chronic Low Back Pain.

This pilot trial examined the effects of a combined intervention of mindfulness meditation followed by aerobic walking exercise compared with a control condition in chronic low back pain patients. We hypothesized that meditation before exercise would reduce disability, pain, and anxiety by increasing mindfulness prior to physical activity compared with an audiobook control group. Thirty-eight adults completed either meditation and exercise treatment (MedExT) (n=18) or an audiobook control condition (n=20). Duquesne University Exercise Physiology Laboratory. A pilot, assessor-blinded, randomized controlled trial. Over a 4-week period, participants in the MedExT group performed 12-17minutes of guided meditation followed by 30minutes of moderate-intensity walking exercise 5days per week. Measures of disability, pain, mindfulness, and anxiety were taken at baseline and postintervention. Pain perception measurements were taken daily. Compared with the control group, we observed larger improvements in disability in the MedExT intervention, although the changes were modest and not statistically significant (mean between-group difference, -1.24; 95% confidence interval [CI], -3.1 to 0.6). For secondary outcome measures, MedExT increased mindfulness (within-group) from pre-intervention to postintervention (P=0.0141). Additionally, mean ratings of low back pain intensity and unpleasantness significantly improved with time for the MedExT group compared with that of the control group, respectively (intensity P=0.0008; unpleasantness P=0.0022). . Overall, 4weeks of MedExT produced suggestive between-group trends for disability, significant between-group differences for measures of pain, and significant within-group increases in mindfulness.

Chronic non-medical prescription opioid use and empathy for pain: Does pain make the difference?

Non-medical prescription opioid use (NMPOU) is at the heart of the opioid epidemic in the United States. Although chronic opioid use is commonly accompanied by deficits in social functioning, little is known about the impact of chronic NMPOU on social cognitive functions. Social neuroscience models suggest that empathy activates similar or even equivalent neural structures as those underpinning the first-hand experience in that emotional state (e.g., pain). Therefore, we measured subjective and psychophysiological responses during an empathy-for-pain task in 23 individuals with NMPOU, objectively confirmed by hair and urine testing, and compared them with 29 opioid-naïve healthy controls. NMPOU individuals showed lower other-related and self-related unpleasantness ratings when seeing others in pain than controls. No differences between the control and NMPOU group were found in skin conductance responses and heart rate variability (HRV) assessed by root mean square of successive differences (RMSSD) in response to the task. However, RMSSD-HRV was strongly negatively correlated with self-related unpleasantness and craving in the NMPOU group. A subsequent mediation analysis showed a total effect of RMSSD-HRV on self-related unpleasantness with no mediation of craving. This indicates that stronger emotion regulation indexed by high RMSSD-HRV might have downregulating effects on sharing others' pain in NMPOU individuals but not in healthy controls, which was further accompanied by decreased ratings of personal distress and empathetic concern. These results contribute to a better understanding of social functioning in chronic opioid users, suggesting adequate emotion regulation and empathy trainings as therapeutic targets for future interventions of opioid use disorders and long-term pain treatment with opioids.

Psychopathic traits predict moral judgements in five moral domains: The mediating effect of unpleasantness

PurposeThe relationship between psychopathic traits and moral judgements has evoked passionate debates among researchers. Psychopathic traits have been characterized as risk factors for immoral behaviours in both non‐forensic and forensic populations; however, whether individuals with elevated psychopathic traits display atypical moral judgements has been controversial. Here, we aim to examine how psychopathic traits are related to moral judgements in five moral foundations (Care, Fairness, Loyalty, Authority, and Sanctity) and further explore how unpleasantness mediates the relationship in non‐forensic and forensic samples.MethodsTwo hundred and twenty five college students and 219 detainees were recruited in two separate surveys. All the participants were asked to complete the moral judgement task in everyday moral scenarios, the unpleasantness ratings for the immoral behaviours and the Levenson Self‐Report Psychopathy Scale (LSRP).ResultsPsychopathic traits predicted the binary moral distinction (moral vs. immoral category) in the Care foundation in the non‐forensic sample. Moreover, psychopathic traits predicted moral acceptability ratings (continuous category) in all of the moral foundations in the non‐forensic sample but only for the Care and Loyalty foundations in the forensic sample. Finally, unpleasantness fully mediated the relationship between psychopathic traits and moral judgements in both samples.ConclusionsOur findings provide further evidence that individuals with elevated psychopathic traits have atypical moral judgements – emphasizing the role of unpleasantness in contributing to this phenomenon. Our study has implications for understanding and treating various deviant behaviours in psychopathic individuals.

Pain Intensity and Unpleasantness in People with Vascular Dementia: A Cross Sectional Study

Pain is a multidimensional sensory and affective experience. People with Vascular Dementia (VaD) experience pain more intensely and have negative emotional responses. Further investigation is needed to understand the neurobiology of pain in VaD. We used experimental thermal pain in a cross-sectional design to determine if adults (age>64) with probable VaD experience increased pain intensity and increased pain unpleasantness during “mild” and “moderate” thermal pain. The final sample included 46 sex- and age-matched adults (23 VaD; 12 female) and controls (23 cognitively intact; 12 female) with an average age of 76.5 years (SD=7.5). Participants reported no daily analgesic use. We used a thermode placed on the thenar eminence to assess temperatures perceived as mild and moderate pain (°C) followed by unpleasantness ratings (0-20 scale). We assessed cognition and depression with the Mini-Mental State Exam (MMSE) and the Geriatric Depression Scale. After controlling for depression, and relative to controls, there was no statistically significant difference in the temperature at which people with VaD perceived mild or moderate pain (p = .086; Cohen’s d: mild=0.55, moderate=0.27). However, there was a statistically significant effect of VaD status on pain unpleasantness (p = .003). People with VaD reported mild and moderate pain as more unpleasant than controls (Cohen’s d = 0.79 and 0.60, respectively). Findings support previous work that people with VaD are at risk of experiencing more pain. Assessing pain intensity and affect can avoid under-treated pain in those with VaD.

Loss of high- or low-frequency audibility can partially explain effects of hearing loss on emotional responses to non-speech sounds

Hearing loss can disrupt emotional responses to sound. However, the impact of stimulus modality (multisensory versus unisensory) on this disruption, and the underlying mechanisms responsible, are unclear. The purposes of this project were to evaluate the effects of stimulus modality and filtering on emotional responses to non-speech stimuli. It was hypothesized that low- and high-pass filtering would result in less extreme ratings, but only for unisensory stimuli. Twenty-four adults (22- 34 years old; 12 male) with normal hearing participated. Participants made ratings of valence and arousal in response to pleasant, neutral, and unpleasant non-speech sounds and/or pictures. Each participant completed ratings of five stimulus modalities: auditory-only, visual-only, auditory-visual, filtered auditory-only, and filtered auditory-visual. Half of the participants rated low-pass filtered stimuli (800 Hz cutoff), and half of the participants rated high-pass filtered stimuli (2000 Hz cutoff). Combining auditory and visual modalities resulted in more extreme (more pleasant and more unpleasant) ratings of valence in response to pleasant and unpleasant stimuli. In addition, low- and high-pass filtering of sounds resulted in less extreme ratings of valence (less pleasant and less unpleasant) and arousal (less exciting) in response to both auditory-only and auditory-visual stimuli. These results suggest that changes in audible spectral information are partially responsible for the noted changes in emotional responses to sound that accompany hearing loss. The findings also suggest the effects of hearing loss will generalize to multisensory stimuli if the stimuli include sound, although further work is warranted to confirm this in listeners with hearing loss.

Effects of Language Context and Cultural Identity on the Pain Experience of Spanish-English Bilinguals.

While language and culture influence cognition, their role in shaping pain remains understudied. We tested whether language and cultural identification influence pain report among Spanish-English bilinguals. Eighty bilingual Hispanics/Latinos (40 female) experienced painful thermal stimulations, providing pain intensity and unpleasantness ratings, on separate English and Spanish testing days. Participants' skin conductance responses (SCRs) during stimulations served as measures of physiological arousal. Bilingual participants showed larger SCRs and higher pain intensity when speaking the language congruent with their dominant cultural identification. That is, those endorsing more Hispanic cultural identification showed higher pain in Spanish, while US-American-dominant participants demonstrated increased pain in English. Follow-up moderated mediation demonstrated that SCRs mediated language effects on pain ratings for participants endorsing greater Hispanic cultural identification. Together, our results suggest language, cultural associations, and bodily arousal synergistically influence pain evaluations among bilingual people, potentially contributing to well-documented health disparities between Hispanic and non-Hispanic communities.

Spatial aspects of pain modulation are not disrupted in adolescents with migraine.

To compare spatial pain modulation capabilities between adolescents with and without migraine. Conditioned pain modulation (CPM) responses at the leg are similar in adolescents with versus without migraine. However, the anatomical region of testing may affect spatial pain modulation capabilities as differences in nociceptive processing between patients with migraine and healthy controls are found in local areas that are near the site of clinical pain but not in nonlocal areas. This study aimed to examine spatial pain modulation capabilities tested by the CPM paradigm using test stimulus applied to a local body area. Nineteen adolescents with migraine (age 14.9±2.3, mean±SD; 16 female) and 20 healthy adolescents (age 13.8±2.5, mean±SD; 16 female) completed this case-control study at Cincinnati Children's Hospital Medical Center. Pressure pain thresholds (PPT) were assessed at the trapezius before and during immersion of the foot in a cold water bath (8°C). In the migraine group (146.0±79.1, mean±SD), compared to healthy controls (248.0±145.5, mean±SD), significantly lower PPT (kilopascal) values were found (estimate=124.28, 95% CI: 58.98, 189.59, p<0.001; effect size: d=1.40). No differences between the groups were found for pain intensity and unpleasantness ratings of cold-water immersion nor the CPM response. This study found altered ascending nociceptive processing of mechanical stimuli at the neck in adolescents with migraine. However, endogenous pain modulatory mechanisms were functional and not altered. In light of other studies, impairments in inhibitory control may not be involved in migraine pathophysiology in pediatric patients regardless of stimulus location.

Visceral hypersensitivity is together with psychological distress and female gender associated with severity of IBS-like symptoms in quiescent ulcerative colitis.

A subset of ulcerative colitis (UC) patients in remission demonstrate IBS-like symptoms. Visceral hypersensitivity is a key pathophysiological mechanism in IBS, but its relevance to IBS-like symptoms in inactive UC remains unclear. UC patients in remission (UCR) were screened for IBS-like symptoms. Rectal sensitivity was assessed with rectal balloon distensions, with determination of sensory thresholds and unpleasantness/pain intensity ratings. Patients completed questionnaires evaluating gastrointestinal (GI) and psychological symptoms. Age- and gender-matched IBS subjects and healthy controls (HC) also underwent a rectal sensitivity test. We included 36 UCR patients (18 with IBS-like symptoms (UCR+IBS) and 18 without (UCR-IBS)), 36 IBS subjects, and 14 HC. UCR and IBS patients were more sensitive to rectal balloon distensions than HC, but no differences between UCR and IBS patients were observed. UCR+IBS patients had lower sensory thresholds and higher unpleasantness ratings than UCR-IBS. In UCR patients, the overall GI symptom severity, pain, and bloating, but not diarrhea, constipation or satiety, were associated with rectal sensitivity. In multivariate analyses, rectal sensitivity, psychological distress, and female gender were identified as factors independently associated with GI symptom severity. 61% of UCR patients demonstrated rectal hypersensitivity, and these patients more commonly reported at least mild bloating and pain, and overall GI symptoms, compared to those with normal rectal sensitivity. Visceral hypersensitivity was associated with IBS-like symptoms, in particular pain and bloating, in inactive UC. Together with psychological factors and female gender, visceral hypersensitivity seems to be involved in GI symptom generation in quiescent UC.

Alterations in Neural Responses and Pain Perception in Older Adults During Distraction.

Although it is acknowledged that pain may be modulated by cognitive factors, little is known about the effect of aging on these control processes. The present study investigated electroencephalographical correlates of pain processing and its cognitive modulation in healthy older individuals. For this purpose, the impact of distraction on pain was evaluated in 21 young (9 men; 20.71 [2.30]) and 20 older (10 men; 66.80 [4.14]) adults. Participants received individually adjusted electrical pain stimuli in a high-distraction condition (one-back task) and in a low-distraction condition (simple letter response task). Pain-related evoked potentials and pain ratings were analyzed. Both groups rated pain as less intense (F(1,39) = 13.954, p < .001) and less unpleasant (F(1,39) = 10.111, p = .003) when it was experienced during the high- rather than the low-distraction condition. However, in comparison to younger participants, older adults gave higher unpleasantness ratings to painful stimulation (F(1,39) = 4.233, p = .046), accompanied by attenuated neural responses (N1-P1 and P3 amplitudes), regardless of the distraction condition (F(1,38) = 6.028 [p = .019] and F(1,38) = 6.669 [p = .014], respectively). Older participants felt pain relief through distraction, like younger participants. However, we also found that aging may enhance affective aspects of pain perception. Finally, our results show that aging is characterized by reduced neural processing of painful stimuli. This phenomenon could be related to the increased vulnerability of older participants to develop chronic pain.

Smell and taste dissociations in the modulation of tonic pain perception induced by a capsaicin cream application.

Pain is a subjective experience characterized by sensory (intensity) and emotional (unpleasantness) aspects. Although literature reports behavioural effects on pain due to smell and taste influence, to our knowledge the relationship between tonic pain induced by a capsaicin cream and these chemosensory systems has never been explored before. The aim of this study was to investigate the modulation of olfactory and gustatory substances having different valence on tonic pain perception mediated by a capsaicin cream application. Sixty healthy volunteers were included in two separated experiments (N=30 smell; N=30 taste) and underwent different valence smell and taste stimulations, while receiving painful stimuli. Perception of pain intensity (the sensory component) and unpleasantness (the affective component) was measured with a numerical rating scale, both during the two aforementioned experiments. Pain unpleasantness rating showed differences only in the smell experiment between the two odourous conditions. In particular, pleasant odour induced lower ratings of pain unpleasantness, while no significant results were found for intensity. Regarding taste, we could not observe significant effects nor for pain unpleasantness or intensity. These findings highlight the potential role of pleasant odours in influencing the affective aspects of pain perception induced by this kind of tonic pain. Such evidence might provide new insight for using chemosensory substances as analgesics for modulating the cognitive aspects of neuropathic pain. This work shows the effect of smell on the emotional component of tonic pain, experimentally induced by capsaicin cream application. Previous literature investigated tonic pain in interaction with smell and/or taste stimuli, but mainly with physical methods such as temperature. Our findings add new information in this field, contributing to a deeper insight on the role of olfaction on this particular kind of tonic pain perception. This approach could open to new investigations aimed to consider odours for pain management.

Neural effects of placebo analgesia in fibromyalgia patients and healthy individuals.

Placebo analgesia is hypothesized to involve top-down engagement of prefrontal regions that access endogenous pain inhibiting opioid pathways. Fibromyalgia (FM) patients have neuroanatomical and neurochemical alterations in pathways relevant to placebo analgesia. Thus, it remains unclear whether placebo analgesic mechanisms would differ in FM patients compared to healthy controls (HCs). Here, using placebo-analgesia-inducing paradigms that included verbal suggestions and conditioning manipulations, we examined whether behavioral and neural placebo analgesic responses differed between 32 FM patients and 46 age- and sex-matched HCs. Participants underwent a manipulation scan, where noxious high and low heat were paired with the control and placebo cream, respectively, and a placebo experimental scan with equal noxious heat temperatures. Before the experimental scan, each participant received saline or naloxone, an opioid receptor antagonist. Across all participants, the placebo condition decreased pain intensity and unpleasantness ratings, decreased activity within the right insula and bilateral secondary somatosensory cortex, and modulated the neurologic pain signature. There were no differences between HCs and FM patients in pain intensity ratings or neural responses during the placebo condition. Despite the perceptual and neural effects of the placebo manipulation, prefrontal circuitry was not activated during the expectation period and the placebo analgesia was unaltered by naloxone, suggesting placebo effects were driven more by conditioning than expectation. Together, these findings suggest that placebo analgesia can occur in both HCs and chronic pain FM patients, without the involvement of opioidergic prefrontal modulatory networks.

A multidimensional assessment of dyspnoea in healthy adults during exercise.

(1) To determine whether healthy humans can distinguish between the intensity and unpleasantness of exertional dyspnoea; (2) to evaluate the reliability of qualitative dyspnoea descriptors during exercise; and (3) to assess the reliability of the Multidimensional Dyspnoea Profile (MDP) METHODS: Forty-four healthy participants (24M:20F, 25 ± 5years) completed maximal incremental cycling tests on three visits. During visit 1, participants rated the intensity and unpleasantness of dyspnoea simultaneously throughout exercise using the modified 0-10 category-ratio Borg scale. On visits 2 and 3, participants rated either the intensity or unpleasantness of dyspnoea alone at the same measurement times as visit 1. On all visits, participants selected qualitative descriptors throughout all exercise intensities from a list of 4, selected relevant qualitative descriptors from a list of 15 at peak exercise, and completed the MDP. Participants rated their dyspnoea intensity significantly higher for a given minute ventilation ([Formula: see text]) compared to dyspnoea unpleasantness (dyspnoea-[Formula: see text] slope: 0.08 ± 0.02 vs. 0.07 ± 0.03 Borg 0-10/Lmin-1, p < 0.001) during visit 1. The onset of intensity ratings occurred at a significantly lower work rate compared to unpleasantness ratings measured on the same exercise test (52 ± 41 vs. 91 ± 53 watts, p < 0.001). Dyspnoea intensity and unpleasantness remained significantly different for a given ventilation even when measured independently on separate exercise tests (p < 0.05). There was good-to-excellent reliability (ICC > 0.60) for the use of qualitative dyspnoea descriptors and the MDP to measure dyspnoea at peak exercise. Exercise-induced dyspnoea in healthy adults can differ in the sensory and affective dimensions, and can be measured reliably using qualitative descriptors and the MDP.

Entraining Alpha Activity Using Visual Stimulation in Patients With Chronic Musculoskeletal Pain: A Feasibility Study.

Entraining alpha activity with rhythmic visual, auditory, and electrical stimulation can reduce experimentally induced pain. However, evidence for alpha entrainment and pain reduction in patients with chronic pain is limited. This feasibility study investigated whether visual alpha stimulation can increase alpha power in patients with chronic musculoskeletal pain and, secondarily, if chronic pain was reduced following stimulation. In a within-subject design, 20 patients underwent 4-min periods of stimulation at 10 Hz (alpha), 7 Hz (high-theta, control), and 1 Hz (control) in a pseudo-randomized order. Patients underwent stimulation both sitting and standing and verbally rated their pain before and after each stimulation block on a 0–10 numerical rating scale. Global alpha power was significantly higher during 10 Hz compared to 1 Hz stimulation when patients were standing (t = −6.08, p < 0.001). On a more regional level, a significant increase of alpha power was found for 10 Hz stimulation in the right-middle and left-posterior region when patients were sitting. With respect to our secondary aim, no significant reduction of pain intensity and unpleasantness was found. However, only the alpha stimulation resulted in a minimal clinically important difference in at least 50% of participants for pain intensity (50%) and unpleasantness ratings (65%) in the sitting condition. This study provides initial evidence for the potential of visual stimulation as a means to enhance alpha activity in patients with chronic musculoskeletal pain. The brief period of stimulation was insufficient to reduce chronic pain significantly. This study is the first to provide evidence that a brief period of visual stimulation at alpha frequency can significantly increase alpha power in patients with chronic musculoskeletal pain. A further larger study is warranted to investigate optimal dose and individual stimulation parameters to achieve pain relief in these patients.

Effect of odor pleasantness on heat-induced pain: An fMRI study.

Odor modulates the experience of pain, but the neural basis of how the two sensory modalities, olfaction and pain, are linked in the central nervous system is far from clear. In this study, we investigated the mechanisms by which the brain modulates the pain experience under concurrent odorant stimulation. We conducted an fMRI study using a 2 × 3 factorial design, in which one of two temperatures (warm, hot) and one of three types of odors (pleasant, unpleasant, no odor) were presented simultaneously. "Hot" temperatures were individually determined as those perceived as painful (mean temperature = 46.9 °C). The non-painful "warm" temperature was set to 40 °C. Participants rated hot compared to warm stimuli as more intense and unpleasant, especially in the presence of an unpleasant odor. Parametric modeling on the intensity ratings activated the pain network, covering brain regions activated by the hot stimuli. The presence of an odor, irrespective of its valence, activated the amygdalae. In addition, the amygdalae showed stimulus-dependent functional couplings with the right supramarginal gyrus and with the left superior frontal gyrus. The coupling between the right amygdala and the left superior frontal gyrus was related to the intensity and unpleasantness ratings of the pain experience. Our results suggest that these functional connections may reflect the integrating process of the two sensory modalities, enabling olfactory influence on the pain experience.

Acceptance-Based Emotion Regulation Reduces Subjective and Physiological Pain Responses.

Acceptance-based regulation of pain, which focuses on the allowing of pain and pain related thoughts and emotions, was found to modulate pain. However, results so far are inconsistent regarding different pain modalities and indices. Moreover, studies so far often lack a suitable control condition, focus on behavioral pain measures rather than physiological correlates, and often use between-subject designs, which potentially impede the evaluation of the effectiveness of the strategies. Therefore, we investigated whether acceptance-based strategies can reduce subjective and physiological markers of acute pain in comparison to a control condition in a within-subject design. To this end, participants (N = 30) completed 24 trials comprising 10 s of heat pain stimulation. Each trial started with a cue instructing participants to welcome and experience pain (acceptance trials) or to react to the pain as it is without employing any regulation strategies (control trials). In addition to pain intensity and unpleasantness ratings, heart rate (HR) and skin conductance (SC) were recorded. Results showed significantly decreased pain intensity and unpleasantness ratings for acceptance compared to control trials. Additionally, HR was significantly lower during acceptance compared to control trials, whereas SC revealed no significant differences. These results demonstrate the effectiveness of acceptance-based strategies in reducing subjective and physiological pain responses relative to a control condition, even after short training. Therefore, the systematic investigation of acceptance in different pain modalities in healthy and chronic pain patients is warranted.

A Randomized Sham-Controlled Cross-Over Study on the Short-Term Effect of Non-Invasive Cervical Vagus Nerve Stimulation on Spinal and Supraspinal Nociception in Healthy Subjects.

The aim of the present study was to test the effects of vagus nerve stimulation (VNS) on the descending pain inhibition, quantified by the nociceptive flexor (RIII) reflex and the conditioned pain modulation (CPM) paradigm, and on supraspinal nociceptive responses, assessed by pain intensity and unpleasantness ratings and late somatosensory evoked potentials (SEPs), in healthy subjects. Non-invasive vagus nerve stimulation (nVNS) showed promising effects on headache and pain treatment. Underlying mechanisms are only incompletely understood but may include the activation of the descending pain inhibitory system and/or the modification of emotional responses to pain. Twenty-seven adult, healthy, and pain-free subjects participated in this double-blind cross-over study conducted at a university research center. They received 4minutes of cervical nVNS or sham stimulation in randomized order. RIII reflexes, pain ratings, and SEPs were assessed before, during, and 5, 15, 30, and 60minutes after nVNS/sham stimulation, followed by CPM testing. The primary outcome was the nVNS effect on the RIII reflex size. Three subjects were excluded after the preparatory session (before randomization), 1 subject was excluded after outlier analysis, leaving 23 for analysis. RIII reflex areas were 917.1±563.8µV×ms (mean±SD) before, 952.4±467.4µV×ms during and 929.2±484.0µV×ms immediately after nVNS and 858.4±489.2µV×ms before, 913.9±539.7µV×ms during and 862.4±476.0µV×ms after sham stimulation, revealing no differences between the immediate effects of nVNS and sham stimulation (F [3,66] =0.67, P=.574). There also were no effects of nVNS over sham on RIII reflex areas up to 60minutes after nVNS (F [1.7,37.4] =1.29, P=.283). Similarly, there was no statistically significant effect of nVNS on pain intensity ratings and thresholds, RIII reflex thresholds, late SEP amplitudes, and the CPM effect, compared to sham. Pain unpleasantness ratings statistically significantly decreased from 4.4±2.4 (NRS 0-10) to 4.1±2.5 during nVNS compared to sham stimulation (F [1,22] =8.74, P=.007), but there were no longer lasting effects (5-60minutes after stimulation). The present study does not support an acute effect of nVNS on descending pain inhibition, pain intensity perception or supraspinal nociception in healthy adults. However, there was a small effect on pain unpleasantness during nVNS, suggesting that nVNS may preferentially act on affective, not somatosensory pain components.

The effect of diaphragm fatigue on the multidimensional components of dyspnoea and diaphragm electromyography during exercise in healthy males

Diaphragm fatigue may increase the intensity (sensory dimension) and unpleasantness (affective dimension) of dyspnoea, which may partially explain why diaphragm fatigue negatively affects exercise performance. We hypothesized that diaphragm fatigue would negatively affect exercise performance via increases in both the intensity and unpleasantness of dyspnoea, and that the increase in dyspnoea would be mechanistically linked to an increase in diaphragmatic EMG (EMGdi ), a surrogate measure of neural respiratory drive. Fatiguing the diaphragm prior to exercise reduced cycling performance and increased both the intensity and unpleasantness of dyspnoea. The change in submaximal dyspnoea unpleasantness was significantly correlated with the change in cycling performance. Pre-fatigue of the diaphragm did not increase EMGdi during exercise and is therefore unrelated to the increase in either the sensory or affective dimension of exertional dyspnoea. The purpose of this study was to examine the effect of diaphragm fatigue on the multidimensional components of dyspnoea and diaphragm electromyography (EMGdi ) during cycling. Sixteen healthy males (age=27±5yr, =45.8±9.8mlkg-1 min-1 ) completed two high-intensity, time-to-exhaustion cycling tests in randomized order: (i) inspiratory pressure threshold loading (PTL) prior to exercise to induce diaphragm fatigue (pre-DF) and (ii) no PTL (control). Diaphragm fatigue after PTL was confirmed via cervical magnetic stimulation of the phrenic nerves. Dyspnoea intensity and unpleasantness were measured throughout exercise with the 0-10 category-ratio Borg scale and following exercise using the Multidimensional Dyspnoea Profile (MDP). EMGdi was continuously recorded via a multipair oesophageal electrode catheter. Time-to-exhaustion decreased with pre-DF vs. control (9.0±5.5 vs. 10.7±7.5min, P=0.023). Pre-DF increased dyspnoea intensity ratings by 0.6±1.0 Borg 0-10 units at the highest equivalent submaximal exercise time (HESET) a participant could achieve in both conditions (P=0.020). Dyspnoea unpleasantness ratings increased with pre-DF by 0.5±1.0, 0.7±1.2 and 0.9±1.4 (all P<0.05) Borg 0-10 units during the 2nd, 3rd and 4th minutes of exercise, respectively. There was a significant correlation between the change in breathing unpleasantness ratings at HESET and the change in time-to-exhaustion (r=0.66, P=0.006). The immediate perception domain, a combination of peak unpleasantness and specific dyspnoea descriptor intensity ratings, was the only component of the MDP that was significantly increased with pre-DF (4.3±1.9 vs. 3.6±1.8, P=0.04). There were no significant differences in EMGdi . In conclusion, diaphragm fatigue has negative effects on multiple domains of dyspnoea, which may partially explain why exercise performance decreases with it.

Aberrant Salience? Brain Hyperactivation in Response to Pain Onset and Offset in Fibromyalgia.

While much brain research on fibromyalgia (FM) focuses on the study of hyperresponsiveness to painful stimuli, some studies suggest that the increased pain-related brain activity often reported in FM studies may be partially explained by stronger responses to salient aspects of the stimulation rather than, or in addition to, the stimulation's painfulness. Therefore, this study was undertaken to test our hypothesis that FM patients would demonstrate elevated brain responses to both pain onset and offset-2 salient sensory events of opposing valences. Thirty-eight FM patients (mean ± SD age 46.1 ± 13.4 years; 33 women) and 15 healthy controls (mean ± SD age 45.5 ± 12.4; 10 women) received a moderately painful pressure stimulus to the leg during blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. Stimulus onset and offset transients were analyzed using a general linear model as stick functions. During pain onset, higher BOLD signal response was observed in FM patients compared to healthy controls in dorsolateral and ventrolateral prefrontal cortices (DLPFC and VLPFC, respectively), orbitofrontal cortex (OFC), frontal pole, and precentral gyrus (PrCG). During pain offset, higher and more widespread BOLD signal response was demonstrated in FM patients compared to controls in frontal regions significantly hyperactivated in response to onset. In FM patients, some of these responses were positively correlated with pain unpleasantness ratings (VLPFC, onset; r = 0.35, P = 0.03), pain catastrophizing scores (DLPFC, offset; r = 0.33, P = 0.04), or negatively correlated with stimulus intensity (OFC, offset; r = -0.35, P = 0.03) (PrCG, offset; r = -0.39, P = 0.02). Our results suggest that the increased sensitivity exhibited by FM patients in response to the onset and offset of painful stimuli may reflect a more generalized hypersensitivity to salient sensory events, and that brain hyperactivation may be a mechanism potentially involved in the generalized hypervigilance to salient stimuli in FM.

Mindfulness meditation is related to sensory-affective uncoupling of pain in trained novice and expert practitioners.

Mindfulness meditation can alleviate acute and chronic pain. It has been proposed that mindfulness meditation reduces pain by uncoupling sensory and affective pain dimensions. However, studies to date have reported mixed results, possibly due to a diversity of styles of and expertise in mindfulness meditation. Furthermore, the interrelations between mindfulness meditation and pain catastrophizing during acute pain remain little known. This cross-sectional study investigated the effect of a style of mindfulness meditation called Open Monitoring (OM) on sensory and affective pain experience by comparing novice (2-day formal training; average ~20hr practice) to expert practitioners (>10.000hr practice). We implemented a paradigm that was designed to amplify the cognitive-affective aspects of pain experience by the manipulation of pain anticipation and uncertainty of stimulus length (8 or 16s thermal pain stimuli). We collected pain intensity and unpleasantness ratings and assessed trait pain catastrophizing with the Pain Catastrophizing Scale (PCS). Across groups, mindfulness meditation reduced unpleasantness, but not intensity ratings compared to attentional distraction. Experts reported a lower score on PCS, reduced amplification of unpleasantness by long painful stimuli, and larger sensory-affective uncoupling than novices particularly during long painful stimuli. In experts, meditation-induced uncoupling spilled over the control condition. Across groups and task conditions, a higher score on PCS predicted lower sensory-affective uncoupling during long painful stimuli and higher ratings of pain intensity during short painful stimuli. These findings suggest that mindfulness meditation specifically down-regulates pain affect as opposed to pain intensity, and that pain catastrophizing undermines sensory-affective uncoupling of pain. In this study, we found that a style of mindfulness meditation referred to as OM reduced unpleasantness but not intensity ratings compared to attentional distraction in trained novice (state effect) and expert meditators (state and trait effects). We also observed that trait pain catastrophizing scores predicted this sensory-affective uncoupling. These findings advance our understanding of the cognitive mechanisms underlying mindfulness meditation and can inform treatment strategies for chronic pain.

Differential neural processing of unpleasant sensory stimulation in patients with major depression

An altered processing of negative salient stimuli has been suggested to play a central role in the pathophysiology of major depression (MD). Besides negative affective and social stimuli, physical pain as a subtype of negative sensory stimulation has been investigated in this context. However, the few neuroimaging studies on unpleasant sensory stimulation or pain processing in MD report heterogeneous findings. Here, we investigated 47 young females, 22 with MD and 25 healthy controls (HC) using fMRI (3.0 T). Four levels of increasingly unpleasant electrical stimulation were applied. Ratings of stimulus intensity were assessed by a visual analogue scale. fMRI-data were analyzed using a 2 × 4 ANOVA. Behavioral results revealed no group differences regarding accuracy of unpleasant stimulation level ratings and sensitivity to stimulation. Regarding neural activation related to increasing levels of unpleasant stimulation, we observed increasing activation of brain regions related to the pain and salient stimulus processing corresponding to increasingly unpleasant stimulation in controls. This modulation was significantly smaller in MD compared to controls, particularly in the dorsal anterior cingulate cortex, the somatosensory cortex, and the posterior insula. Overall, brain regions associated with the processing of unpleasant sensory stimulation, but also associated with the salience network, were highly reactive but less modulated in female patients with MD. These results support and extent findings on altered processing of salience and of negative sensory stimuli even of a non-painful quality in female patients with MD.