Acute Pain, Brain Modulation, Neuroplasticity, Somatosensory Function
Conditions
Keywords
tDCS, HD-tDCS, Somatosensory function, QST, quantitative sensory testing, Non-invasive brain stimulation, NIBS, Transcranial Direct Current Stimulation
Brief summary
The purpose of this study is to investigate the efficacy of high definition tDCS on different cortical targets in modulating the nociceptive system in the healthy subjects.
Detailed description
The investigators aim to investigate the efficacy of different HD-tDCS electrode configurations on modulating the somatosensory/nociceptive system. This is done to investigate the hypothesis, that different stimulation protocols can be used to modulate the somatosensory and nociceptive system, as shown in the previous studies, but that it is necessary to uncover the most efficient way to do so. The study uses a double-blinded, sham-controlled, longitudinal design, where quantitative sensory testing will be used to assess the somatosensory function of the participants before and after a receiving a specific configuration of HD-tDCS on three consecutive days.
Interventions
Using the Starstim 32, HD-tDCS equipment we provide 20 minutes of 2 mA anodal stimulation of primary motor cortex (M1) using a ring-cathode configuration
DEVICEDorsolateral Prefrontal Cortex Stimulation
Using the Starstim 32, HD-tDCS equipment we provide 20 minutes of 2 mA anodal stimulation of dorsolateral prefrontal cortex (DLPFC) using a ring-cathode configuration
DEVICEMultimodal Stimulation (DLPFC+M1)
Using the Starstim 32, HD-tDCS equipment we provide 20 minutes of 2 mA anodal multimodal stimulation of dorsolateral prefrontal cortex (DLPFC) and primary motor cortex simultaneously using ring-cathode configurations around the two anodes.
DEVICESham stimulation
Using the Starstim 32, HD-tDCS equipment we provide sham stimulation with 30 seconds of ramping up to 2 mA intensity, then turning off for 19 minutes and then ramping down from 2 mA intensity to 0 in the last 30 seconds.
Sponsors
Danish National Research Foundation
Aalborg University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
The stimulation protocol is blinded and randomized using the software's double-blinding function. The subjects are randomly assigned to one of four groups receiving the corresponding stimulation protocol. One of which is a sham-stimulation (placebo), that imitates the experience of real stimulation.
Intervention model description
Longitudinal, sham-controlled, parallel groups design.
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
* Healthy men and women. * Able to speak, read and understand English or Danish.
Exclusion criteria
* Pregnancy * Drug addiction defined as the use of cannabis, opioids or other drugs * Current use of opioids, antipsychotics, benzodiazepines * Previous or current neurological, musculoskeletal, rheumatic, malignant, inflammatory or mental illnesses * Current or prior chronic pain conditions * Lack of ability to cooperate
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in pressure pain threshold | Six assessments over three days: Baseline is assessed before any intervention at day one, and then the pain thresholds are assessed before and after each intervention on the subsequent two days. | A hand-held pressure algometer (Somedic, Hörby, Sweden) with a 1-cm2 probe will be used to record the pressure pain threshold. The pressure is increased gradually at a rate of 30 kPa/s. The measurement is repeated three times on on flexor carpi radialis. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in mechanical pain threshold | Six assessments over three days: Baseline is assessed before any intervention at day one, and then the sensory thresholds are assessed before and after each intervention on the subsequent two days. | Mechanical pain threshold (MPT) will be measured using a set of weighted pinprick stimulators with a flat contact area of 0.25 mm diameter that exert forces between 8 and 512 mN. Threshold procedures will use a method of limits with up to five series of ascending and descending stimulus intensities. This will be assessed on flexor carpi radialis on the right hand arm. |
| Change in Thermal Sensory Detection | Six assessments over three days: Baseline is assessed before any intervention at day one, and then the sensory thresholds are assessed before and after each intervention on the subsequent two days. | A 3×3 cm (9 cm2) contact thermode (Medoc Advanced Medical Systems, Israel) will be used to apply thermal stimulation. Each stimulus will be started at 32°C and thresholds of heat and cold sensory detection will be assessed by ascending or descending ramps in temperature to the cutoffs of 0-50 °C. This will be assessed on flexor carpi radialis on the right hand arm. |
| Change in Thermal Pain Detection | Six assessments over three days: Baseline is assessed before any intervention at day one, and then the sensory thresholds are assessed before and after each intervention on the subsequent two days. | A 3×3 cm (9 cm2) contact thermode (Medoc Advanced Medical Systems, Israel) will be used to apply thermal stimulation. Each stimulus will be started at 32°C and thresholds of heat and cold pain detection will be assessed by ascending or descending ramps in temperature to the cutoffs of 0-50 °C. This will be assessed on flexor carpi radialis on the right hand arm. |
| Change in tactile detection threshold | Six assessments over three days: Baseline is assessed before any intervention at day one, and then the sensory thresholds are assessed before and after each intervention on the subsequent two days. | Tactile threshold will be measured using an anaesthesiometer consisting of a set of Von Frey filaments. The filaments are made of nylon fibre of various diameters so as to provide a range of forces of up to 300 grams. The minimum force that the subject can detect will be identified. This will be assessed on flexor carpi radialis on the right hand arm. |
| Change in vibration detection threshold. | Six assessments over three days: Baseline is assessed before any intervention at day one, and then the sensory thresholds are assessed before and after each intervention on the subsequent two days. | Vibration detection threshold (VDT) will be determined with a Rydel-Seiffer tuning fork (64 Hz, 8/8 scale), which will be placed three times over a bony prominence of the distal part of the ulna on the right arm. Subjects are to indicate the disappearance of vibratory sensations. |
| Change in temporal summation of pain (TSP). | Six assessments over three days: Baseline is assessed before any intervention at day one, and then the sensory thresholds are assessed before and after each intervention on the subsequent two days. | TSP will be applied using cuff pressure algometry. A total of 10 repeated mechanical pressure stimuli will be delivered at 0.5 Hz (1-s stimuli duration and 1-s interval between stimuli) to the test area. During the 10 repeated stimuli, subjects will continuously rate the pain intensity on a 10-cm continuous VAS. TSP is assessed on the calf of the right leg. |
| Change in conditioned pain modulation (CPM) | Six assessments over three days: Baseline is assessed before any intervention at day one, and then the sensory thresholds are assessed before and after each intervention on the subsequent two days. | A computer-controlled cuff pressure algometer (Nocitech, Denmark) with an air-filled tourniquet cuff (VBM, Germany) will be used to record cuff pressure-induced pain thresholds over the muscle bulk on the calfs. The pressure is increased gradually at a rate of 1 kPa/s to assess pain tolerance on a 0-10 VAS scale, where 0 is no pain at all and 10 is the worst pain imaginable. During CPM testing, the pain tolerance is first assessed on one leg marking the baseline. The pressure pain tolerance is then assessed on the same leg again, while the contralateral calf is applied a simultaneous painful pressure stimulus. The outcome of the CPM testing is the difference in pressure pain tolerance measured in kPA between the first and the second assessment. The larger the positive difference is between the baseline and the second assessment, the stronger CPM effect the subject has. |
Countries
Denmark
Outcome results
None listed