映射应力和疼痛相互作用（G072323N） (STRAIN)

Proof of a primary fibromyalgia diagnosis with chronic widespread pain by a specialist-doctor, with an average pain intensity of ≥2/10 on a Visual Analogue Scale, and with pain-related disability indicated by a score of ≥14/70 on the Pain Disability Index.

Chronic primary (non-specific) low back pain with primary onset ≥6 months ago, with an average pain intensity of ≥2/10 on a Visual Analogue Scale, and with pain-related disability indicated by a score of ≥14/70 on the Pain Disability Index.

Non-specific low back pain with primary onset <3 months ago, with an average pain intensity of ≥2/10 on a Visual Analogue Scale, and with pain-related disability indicated by a score of ≥14/70 on the Pain Disability Index.

Exclusion criteria include current pain (>0 on a Visual Analogue Scale); a pain condition in the last 6 months for which treatment was sought; history of a chronic pain syndrome.

Determination of mechanical pain sensitivity with a digital pressure algometer, recorded in kg.

Determination of the mean of heat pain threshold and heat pain tolerance with TSA-2, recorded in °C.

Determination of conditioned pain modulation with a parallel protocol, with test stimulus and conditioning stimulus equal to the heat pain suprathreshold temperature. Pain will be scored on a verbal rating scale 0-100.

Determination of temporal summation of pain with a tonic protocol. Heat stimuli will be applied for two minutes, with the temperature equal to the heat pain suprathreshold. Pain will be scored on a verbal rating scale 0-100.

This type of functional MRI-scanning will allow to capture acute brain responses to (painful) heat stimuli and processes of pain modulation.

Saliva samples will be taken, with a swab under the tongue for 2 minutes to analyse cortisol concentration; providing information about the hypothalamus-pituitary-adrenal-axis functioning.

Saliva samples will be taken, with a swab under the tongue for 2 minutes to analyse alpha-amylase concentrations; which gives information about the autonomic nervous system functioning.

Saliva samples will be taken, with a swab under the tongue for 2 minutes to analyse oxytocin concentrations; providing information about the oxytocinergic system.

Heart rate, the number of times the heart beat within a certain period, will be measured continuously using ECG (electrocardiogram), providing information on the autonomic nervous system.

Heart rate variability (HRV), the fluctuations in time between heart beats, will be measured continuously using ECG. Both time domain and frequency domain of HRV will be examined; providing information on the autonomic nervous system.

Skin conductance reflects sweat gland activity and will be measured continuously; providing information on the autonomic nervous system.

Skin temperature, the measurement of the temperature at the skin's surface will be measured continuously; providing information on the autonomic nervous system.

Respiration rate, the number of breaths taken per minute will be measured continuously; providing information on the autonomic nervous system.

Blood pressure, the force exerted by circulating blood on the walls of blood vessels, will be measured using non-continuously; providing information on the autonomic nervous system.

Assessment of momentary pain, unpleasantness and stress on a VAS scale ranging from 0-100

Assessment of pain-related interference in daily activities, recorded on a 0-70 scale

Measurement of catastrophic thinking related to pain, recorded on a scale of 0-52.

Assessment of attention and awareness to pain, recorded on a 0-80 scale.

11-point scale to rate perceived recovery from - 5 (vastly worse), through 0 (no change) to + 5 (greatly improved), to assess recovery or persistence of low back pain

Assessment of fear and anxiety associated with pain, recorded on a 0-100 scale.

Measurement of positive and negative affect levels. Total scores for positive and negative affect range for 10-50 separately.

Measurement of the ability to recover from stress, recorded on a 5-point Likert scale. This questionnaire contains 6 items.

Assessment of intolerance to uncertainty, recorded on a scale of 1-5 for each item, with 12 items in total.

Evaluation of beliefs about the nature of stress (enhancing vs. debilitating), recorded on a scale of 0-4 for each item, with 8 items in total.

Measurement of perceived stress over the past month, recorded on a scale of 0-40.

Assessment of anxiety and depression symptoms, recorded on a scale of 0-21 for anxiety and depression subscales separately.

Measurement of childhood trauma experiences. A shortened version will be used with scores ranging from 0-25. Emotional abuse, physical abuse, and neglect components will be assessed.

Measurement of sleep quality over the past month. A shortened version will be used with scores ranging from 0-12. Component 1-4 will be scored.

Collection of scales of measures for gender conceptualization, gender identity and gendered pain beliefs

Through Magnetization Prepared-Rapid Gradient Echo, macro-structural properties of grey matter, such as surface area, cortical thickness or volume will be characterized.

This type of MRI-scan will allow us to evaluate functional connectivity of the brain.

Diffusion weighted MR imaging will provide insights in microstructural properties of white matter (i.e., factional anisotropy, mean diffusivity, etc.).

This type of MRI will provide information on brain blood perfusion parameters.

Determination of mechanical pain sensitivity with a digital pressure algometer, recorded in kg.

Determination of the mean of heat pain threshold and heat pain tolerance with TSA-2, recorded in °C.

Determination of conditioned pain modulation with a parallel protocol, with test stimulus and conditioning stimulus equal to the heat pain suprathreshold temperature. Pain will be scored on a verbal rating scale 0-100.

Determination of temporal summation of pain with a tonic protocol. Heat stimuli will be applied for two minutes, with the temperature equal to the heat pain suprathreshold. Pain will be scored on a verbal rating scale 0-100.

This type of functional MRI-scanning will allow to capture acute brain responses to (painful) heat stimuli and processes of pain modulation.

Saliva samples will be taken, with a swab under the tongue for 2 minutes to analyse cortisol concentrations; providing information about the hypothalamus-pituitary-adrenal-axis functioning.

Saliva samples will be taken, with a swab under the tongue for 2 minutes to analyse alpha-amylase concentrations; providing information about the autonomic nervous system functioning.

Saliva samples will be taken, with a swab under the tongue for 2 minutes to analyse oxytocin concentrations; providing information on the oxytocinergic system.

Heart rate, the number of times the heart beat within a certain period, will be measured with ECG continuously, and is part of the autonomic nervous system.

Heart rate variability, the fluctuations in time between heart beats, will be measured with ECG continuously. Both time domains and frequency domains of HRV will be examined. This parameter is part of the autonomic nervous system.

Skin conductance reflects sweat gland activity and will be measured continuously; providing information on the autonomic nervous system.

Skin temperature, the measurement of the temperature at the skin's surface will be measured continuously; providing information on the autonomic nervous system.

Respiration rate, the number of breaths taken per minute will be measured continuously; providing information on the autonomic nervous system.

Blood pressure, the force exerted by circulating blood on the walls of blood vessels, will be measured using non-continuously; providing information on the autonomic nervous system.