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Interoception, or the sense of the internal state of the body, is hypothesized to be essential for a wide range of psychobiological processes and the development and perpetuation of several (mental) health problems. However, the study of interoceptive accuracy, the objectively measured capacity to detect or discriminate conscious bodily signals, has been hampered by the use of tasks with questionable construct validity and is often limited to studying interoception solely in the cardiac domain. We developed a novel task to measure interoceptive accuracy in the respiratory domain, the respiratory occlusion discrimination (ROD) task. In this task, interoceptive accuracy is defined as an individual's ability to detect small differences in lengths of short respiratory occlusions, assessed by means of an adaptive staircase procedure. This article describes a validation study (N = 97) aimed at investigating the internal consistency, test-retest reliability, and discriminant validity of the ROD task. The average just noticeable difference of lengths of respiratory occlusion was 74.22 ms, with large inter-individual variability (SD = 37.1 ms). The results of the validation study indicate acceptable internal consistency (Cronbach's alpha = 0.70), 1-week test-retest reliability (r = 0.53), and discriminant validity, as indicated by a lack of correlation between the ROD task and an auditory discrimination task with identical design (r = 0.18), and a weak correlation with breathing behavior (r = -0.27). The ROD task is a promising novel paradigm to study interoceptive accuracy and its role in various psychobiological processes and disorders. ispartof: PSYCHOPHYSIOLOGY vol:58 issue:4 ispartof: location:United States status: published

Impaired selective fear learning has been advanced as a core mechanism involved in excessive spreading of protective responses such as pain-related fear and avoidance leading to disability in chronic pain conditions. Using the litmus test for selective learning effects, the blocking procedure, we tested the hypothesis that patients with fibromyalgia (FM) show less selective threat learning than healthy controls (HCs). We introduce a novel selective learning task based around a clinical diary scenario. On a trial-by-trial basis, participants rated whether they expected certain situations (A, B, Z, and X) in the diary of a fictive FM patient would trigger pain in that patient. The procedure did not involve any experimental pain induction because the verbal outcomes "pain" or "no pain" were used. During the elemental acquisition phase, one situation was followed by "pain" (A+, eg, "Kim slept badly, and reports pain"), whereas another situation was followed by "no pain" (Z-, eg, "Kim was stressed, and reports no pain"). During the compound acquisition phase, another situation (X), referred to as the blocked stimulus, was presented in compound with a previously pain-eliciting situation and also paired with "pain" (AX+, eg, Kim slept badly" and "Kim has vacuumed," and reports pain). Simultaneously, a novel situation was introduced and also followed by "pain" (B+). Within-group comparisons showed blocking (ie, significant difference between B and X) in the HCs, but not in the patients with FM. This study is the first in directly assessing differences in selective learning between patients with FM and HCs using a blocking procedure. ispartof: Pain vol:159 issue:7 pages:1268-1276 ispartof: location:United States status: published

Objective Patients with functional somatic syndromes show reduced correspondence between induced physiological changes and self-reported symptoms in a rebreathing paradigm, as well as elevated symptoms unrelated to physiological changes after induction of negative affective states in an affective picture-viewing paradigm. Detailed results of both paradigms separately were published elsewhere. The main goal of the current report is to describe the relationship between the responses to these two paradigms measuring distortions in symptom perception in a well-described sample of patients with fibromyalgia and/or chronic fatigue syndrome. Methods Patients (N = 81) with fibromyalgia and/or chronic fatigue syndrome participated in a test session comprising four well-validated paradigms, including the picture-viewing and rebreathing paradigm. Using mixed model analyses, we tested whether the amount of affective modulation of symptom reporting was related to distorted perception of induced dyspnea. In an exploratory way, we assessed the role of several individual difference variables as moderators. Results There was no relationship between patients' amount of affective modulation of symptom reporting, as assessed with the picture paradigm, and level of distortion in dyspnea perception, as assessed with the rebreathing paradigm (effect of affective modulation in the subjective recovery from induced dyspnea: F-1,F-70 = 0.16, p = .70; time by affective modulation interaction effect: F-4,F-70 = 0.14, p = .97). Conclusions Biased symptom reporting in one paradigm is unrelated to biased symptom reporting in the other paradigm, indicating that distortions in symptom perception in patients with functional somatic syndromes are not a trait-like, cross-situationally stable condition, but a versatile dysfunction that is context dependent. This study was funded by the Center for Excellence on Generalization Research (GRIP*TT; University of Leuven grant PF/10/005) and by Asthenes, a long-term structural funding-Methusalem grant by the FWO-Vlaanderen, Flemish Government, Belgium. The study was further supported by infrastructure grants from the Herculesstichting, Belgium (AKUL/13/07 and AKUL/11/08). The authors report no conflicts of interest.

Background: Several studies have shown that patients with functional somatic syndromes have, on average, deficient endogenous pain modulation (EPM), as well as elevated levels of negative affectivity and high comorbidity with depression and reduced resting heart rate variability (HRV) compared to healthy controls. The goals of this study were 1) to replicate these findings and 2) to investigate the moderating role of negative affectivity, depression and resting HRV in EPM efficiency within a patient group with fibromyalgia and/or chronic fatigue syndrome. Resting HRV was quantified as the root mean square of successive differences between inter-beat intervals (RMSSD) in rest, a vagally-mediated time domain measure of HRV. Methods: Seventy-eight patients with fibromyalgia and/or chronic fatigue syndrome and 33 healthy controls completed a counter-irritation paradigm as a measure of EPM efficiency. Participants rated the painfulness of electrocutaneous stimuli (of individually calibrated intensity) on the ankle before (baseline phase), during (counter-irritation phase) and after (recovery phase) the application of a cold pain stimulus on the forearm. A larger reduction in pain in the counter-irritation phase compared to the baseline phase reflects a more efficient EPM. Results: In contrast to our expectations, there was no difference between pain ratings in the baseline compared to counter-irritation phase for both patients and healthy controls. Therefore, reliable conclusions on the moderating effect of negative affectivity, depression and RMSSD could not be made. Surprisingly, patients reported more pain in the recovery compared to the counter-irritation and baseline phase, while HC did not. This latter effect was more pronounced in patients with comorbid depression, patients who rated the painfulness of the counter-irritation stimulus as high and patients who rated the painfulness of the electrocutaneous stimuli as low. Conclusion: We did not manage to successfully replicate the counter-irritation effect in healthy controls or FSS patients. Therefore, no valid conclusions on the association between RMSSD, depression, negative affectivity and EPM efficiency can be drawn from this study. Possible reasons for the lack of the counter-irritation effect are discussed. This work was supported by the Center for Excellence on Generalization Research (GRIP*TT; University of Leuven grant PF/10/005) and by Asthenes, a Long-Term Structural Funding-Methusalem grant by the FWO-Vlaanderen, Flemish Government, Belgium. The study was further supported by infrastructure grants from the Herculesstichting, Belgium (AKUL/13/07 and AKUL/11/08).

Objective: Dyspnea perception is distorted in patients with medically unexplained dyspnea. The goals of this study were 1) to replicate these results in patients with fibromyalgia and/or chronic fatigue syndrome (CFS), and 2) to investigate predictors of distorted symptom perception within the patient group, with a focus on negative affectivity (NA), psychiatric comorbidity and somatic symptom severity. Methods: Seventy-three patients diagnosed with fibromyalgia and/or CFS and 38 healthy controls (HC) completed a rebreathing paradigm, consisting of a baseline (60s of room air), a rebreathing phase (150s, gradually increasing ventilation, partial pressure of CO2 in the blood, and self-reported dyspnea), and a recovery phase (150s of room air). Dyspnea, respiratory flow and FetCO2 levels were measured continuously. Results: Patients reported more dyspnea than HC in the recovery phase (p = 0.039), but no differences between patients and HC were found in the baseline (p = 0.07) or rebreathing phase (p = 0.17). No significant differences between patients and HC were found in physiological reactivity. Within the patient group, the effect in the recovery phase was predicted by somatic symptom severity (p = 0.046), but not by negative affectivity or by the number of psychiatric comorbidities. Conclusion: This study extended earlier findings in patients with medically unexplained dyspnea to patients with fibromyalgia and CFS. This suggests that altered symptom perception is a non-symptom-specific mechanism underlying functional somatic syndromes in general, particularly in patients with high levels of somatic symptom severity . The results are discussed in a predictive coding framework of symptom perception. The authors would like to thank the physicians and psychologists at the Psychiatry Departments of UZ Gasthuisberg, ZOL Genk, and at the Rheumatology Center in Genk for their help with the recruitment of patients; Mathijs Franssen for his help with data processing; and Katrien Coremans, Lotte Ceuterick, and Celine Samaey for their help with data collection. This research was funded by the Center for Excellence on Generalization Research (GRIP*TT; University of Leuven grant PF/10/005) and by Asthenes, a long-term structural funding-Methusalem grant (METH/15/011) by the FWO-Vlaanderen, Flemish Government, Belgium. The study was further supported by infrastructure grants from the Herculesstichting, Belgium (AKUL/13/07 and AKUL/11/08).

OBJECTIVE: Induction of negative affective states can enhance bodily symptoms in high habitual symptom reporters among healthy persons and in patients with irritable bowel syndrome. The aims of this study were to replicate this effect in patients with fibromyalgia and chronic fatigue syndrome and to investigate the role of moderators, focusing on alexithymia, negative affectivity, and absorption. METHODS: Patients with fibromyalgia and/or chronic fatigue syndrome (n = 81) and HCs (n = 41) viewed series of neutral, positive, and negative affective pictures. After every picture series, participants filled out a somatic symptom checklist and rated emotions experienced during the picture series on valence, arousal, and perceived control. RESULTS: Patients reported more somatic symptoms after viewing negative pictures (least square mean [LSM] = 19.40, standard error (SE) = 0.50) compared with neutral (LSM = 17.59, SE = 0.42, p < .001) or positive (LSM = 17.04, SE = 0.41, p < .001) pictures, whereas somatic symptom ratings of HCs after viewing negative picture series (LSM = 12.07, SE = 0.71) did not differ from ratings after viewing neutral (LSM = 11.07, SE = 0.59, p = .065) or positive (LSM = 11.10, SE = 0.58, p = .93) pictures. Negative affectivity did not moderate the symptom-enhancing effect of negative affective pictures, whereas the alexithymia factor "difficulty identifying feelings" and absorption did (p = .016 and p = .006, respectively). CONCLUSION: Negative affective states elicit elevated somatic symptom reports in patients experiencing fibromyalgia and/or chronic fatigue syndrome. This symptom-enhancing effect is greater in patients having higher difficulty to identify feelings and higher absorption scores. The results are discussed in a predictive coding framework of symptom perception. This study was supported by the Center for Excellence on Generalization Research (GRIP*TT; University of Leuven Grant PF/10/005) and by Asthenes, a long-term structural funding-Methusalem grant by the FWO-Vlaanderen, Flemish Government, Belgium. The study was further supported by infrastructure grants from the Herculesstichting, Belgium (AKUL/13/07 and AKUL/11/08). The authors report no conflicts of interest.