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The aim of this project is to determine the effects of performing a motor imagery task on cortical excitability during acute experimental muscle pain (induced by hypertonic saline), acute histaminergic itch (induced by histamine), and non-histaminergic itch stimulation (triggered by Cowhage). We hypothesize that motor imagery will counteract the alterations in cortical excitability observed during experimental muscle pain and both itch models.
Itch and pain share many similarities and dissimilarities in terms of the mechanisms and molecules involved. Many studies have been conducted to explain all the neurophysiological aspects involved in the pain process, and cortical adaptations have been provoked in healthy individuals using experimental pain models. Unfortunately, all these aspects still need to be clarified regarding itch. Has been previously demonstrated that motor imagery can counteracted the pain-induced decrease in corticospinal excitability observed during acute pain, and it has also been proposed as a potential intervention for individuals with pain to restore maladaptive neuroplasticity. However, whether motor imagery can similarly counteract the itch-induced cortical changes remains unclear. Therefore, the aim of this project is to investigate whether motor imagery would counteract the reduction in cortical excitability during acute itch, similar to the effects observed in the context of acute pain.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Experimental:Healthy volunteers | Experimental |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Hypertonic Saline | Other | A bolus injection of hypertonic saline (7% NaCl) will be administered to the FDI muscle using a 1 mL syringe with a disposable needle (27G), and the volume of the bolus will be 0.1 mL |
| Measure | Description | Time Frame |
|---|---|---|
| Numeric rating scales (NRS) | NRS are essentially VAS but have tick marks spaced every centimeter so as to create 11-point scale (from 0 to 10). Subject can use these tick marks as a guide when they mark their severity on the scale. | 1 minute after every itch/pain induction |
| Measuring cortical excitability (TEPs) | Transcranial magnetic stimulation (TMS) with a figure-eight-shaped cone coil will be used to evoke cortical responses in the motor cortex. The resulting TMS-evoked potentials (TEPs) will be collected using an electroencephalogram (EEG). This assessment will last for 7 minutes before inducing itch or pain. | Baseline |
| Measuring cortical excitability (TEPs) | Transcranial magnetic stimulation (TMS) with a figure-eight-shaped cone coil will be used to evoke cortical responses in the motor cortex. The resulting TMS-evoked potentials (TEPs) will be collected using an electroencephalogram (EEG). This assessment will last for 7 minutes during itch or pain. The pain or itch sensation will last 10 minutes. | During Itch/pain stimulation for 10 minutes |
| Measuring cortical excitability (TEPs) | Transcranial magnetic stimulation (TMS) with a figure-eight-shaped cone coil will be used to evoke cortical responses in the motor cortex. The resulting TMS-evoked potentials (TEPs) will be collected using an electroencephalogram (EEG). This assessment will last for 7 minutes during motor imagery task. | During motor imagery task for 7 minutes |
| Measuring cortical excitability (TEPs) | Transcranial magnetic stimulation (TMS) with a figure-eight-shaped cone coil will be used to evoke cortical responses in the motor cortex. The resulting TMS-evoked potentials (TEPs) will be collected using an electroencephalogram (EEG). Similar to the baseline, this assessment will last for 7 minutes after itch or pain. |
| Measure | Description | Time Frame |
|---|---|---|
| Pain Catastrophizing Scale (PCS). | The PCS assesses negative and exaggerated coping concerning anticipated or experienced painful stimuli. Thirteen items have to be answered on a 5-point Likert-type scale. | Baseline |
| Itch Catastrophizing Scale (ICS). |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Silvia Lo Vecchio | Contact | 21397785 | slv@hst.aau.dk |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Aalborg University | Recruiting | Gistrup | 9260 | Denmark |
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we apply one of three experimental methods in your hand: either an injection of salt water (7% NaCl) or we apply small needles from the plant mucuna pruriens or histamine (1%)
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| Histamine | Other | A small drop of histamine dihydrochloride will be applied to a previously determined area on the volar forearm, followed by a prick through the drop |
|
| Cowhage | Other | This insertion is conducted by forceps using a stereomicroscope, and 30-35 spicules are gently rubbed into a 1 cm diameter skin area. |
|
| Transcranial magnetic stimulation (TMS) | Device | Transcranial magnetic stimulation (TMS) will be used to evoke motor-evoked potentials (MEPs) in the muscle of interest and cortical responses (TMSevoked potentials - TEPs) in the motor cortex with a figure-eight-shaped cone coil. |
|
| Post induction of itch or pain |
The ICS assesses negative and exaggerated coping concerning anticipated or experienced itchy stimuli. Thirteen items have to be answered on a 5-point Likert-type scale.
| Baseline |
| Reinforcement Sensitivity Theory - Personality Questionnaire (RST-PQ). | The RST-PQ contains the following subscales: the Fight-Flight-Freeze System (FFFS, 10 items), which represents a defensive factor related to active avoidance of adverse stimuli; the Behavioral Inhibition System (BIS, 23 items), which represents a defensive factor related to anxiety and passive avoidance of adverse stimuli; and the Behavioral Approach System (BAS, 32 items), which reflects reward interest, goal-drive persistence, reward reactivity, and impulsivity. In total, 65 items have to be answered on a 4-point Likert-type scale | Baseline |
| The Pittsburg Sleep Quality Index (PSQI) | The PSQI consists of 19 items generating seven component scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The seven component scores can be summarized in a global score ranging from zero to 21 with higher scores reflecting a worse overall quality of sleep | Baseline |
| Depression, Anxiety, Stress Scale (DASS-21) | The questionnaire measures the magnitude of depression, anxiety, and stress. Each of these three subscales consists of 7 questions answered using a 0-3 Likert scale, with 0 meaning "it did not apply to me", and 3 meaning "it applied to me very much". | Baseline |
| Learned Helplessness Scale (LHS) | The questionnaire consists of 20 items, and the participant's response to each item is rated on a 4-point Likert scale ranging from strongly agree (1) to strongly disagree (4). | Baseline |
| Positive And Negative Affect Schedule (PANAS) | PANAS measures positive and negative affect dimensions. Twenty words are associated with the subject's current feelings and have to be rated on a 5-points Likert-type scale. | Baseline |
| Aalborg University | Recruiting | Gistrup | 9260 | Denmark |
|
| ID | Term |
|---|---|
| D011537 | Pruritus |
| D010146 | Pain |
| ID | Term |
|---|---|
| D012871 | Skin Diseases |
| D017437 | Skin and Connective Tissue Diseases |
| D012877 | Skin Manifestations |
| D012816 | Signs and Symptoms |
| D013568 | Pathological Conditions, Signs and Symptoms |
| D009461 | Neurologic Manifestations |
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| ID | Term |
|---|---|
| D012462 | Saline Solution, Hypertonic |
| D006632 | Histamine |
| D050781 | Transcranial Magnetic Stimulation |
| ID | Term |
|---|---|
| D006982 | Hypertonic Solutions |
| D012996 | Solutions |
| D004364 | Pharmaceutical Preparations |
| D015306 | Biogenic Monoamines |
| D001679 | Biogenic Amines |
| D000588 | Amines |
| D009930 | Organic Chemicals |
| D005021 | Ethylamines |
| D007093 | Imidazoles |
| D001393 | Azoles |
| D006573 | Heterocyclic Compounds, 1-Ring |
| D006571 | Heterocyclic Compounds |
| D012898 | Autacoids |
| D018836 | Inflammation Mediators |
| D001685 | Biological Factors |
| D055909 | Magnetic Field Therapy |
| D013812 | Therapeutics |
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