Modulating Pain Using Transcranial Alternating Stimulation (tACS) in Healthy Human Subjects

Not Applicable

Completed

• Conditions: Experimental Pain in Healthy Human Subjects
• Interventions: Device: 10 Hz tACS of the bilateral somatosensory cortex; Device: 10 Hz tACS of the prefrontal cortex; Device: 80 Hz tACS of the bilateral somatosensory cortex; Device: 80 Hz tACS of the prefrontal cortex; Device: Sham stimulation of the bilateral somatosensory cortex; Device: Sham stimulation of the prefrontal cortex

• Registration Number: NCT03805854
• Lead Sponsor: Technical University of Munich

Brief Summary

Pain is a highly complex and subjective phenomenon which results from the dynamic integration of sensory and contextual (i.e. cognitive, emotional, and motivational) processes. Recent evidence suggests that neural oscillations and their synchronization between different brain areas might form the basis of these integrative functions. When investigating tonic experimental pain lasting for several minutes, for example, objective stimulus intensity is inversely related to alpha (8-13 Hz) and beta (13-30 Hz) oscillations in early somatosensory areas, while subjective pain intensity is positively associated with gamma (30-100 Hz) oscillations in prefrontal cortex. Yet, with a few exemptions, reported links between oscillatory brain activity and pain have mostly been established by correlative approaches which do not allow to infer causality. The current project aims at comprehensively investigating the causal role of neural oscillations for tonic experimental pain in healthy human subjects. To this end, transcranial alternating current stimulation (tACS) will be employed to modulate oscillatory brain activity in alpha and gamma frequency bands and investigate effects of this manipulation on pain perception and pain-related autonomic responses. Using an established tonic pain stimulation protocol and a double-blind, sham-controlled design, effects of tACS of somatosensory as well as prefrontal brain areas will be investigated. Results promise to elucidate the neural mechanisms underlying tonic experimental pain by testing the mechanistic role of neural oscillations in different aspects of pain processing. Furthermore, they might contribute to the development of urgently needed new treatment approaches for chronic pain using neuromodulatory methods.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2019-01-10
• Study First Submitted QC: 2019-01-15
• Study First Posted: 2019-01-16
• Study Start: 2019-04-15
• Primary Completion: 2019-10-23
• Study Completion: 2019-10-23
• Status Verified: 2020-06
• Last Update Submitted: 2020-06-02
• Last Update Posted: 2020-06-04

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 39

Inclusion Criteria

• aged 18-65 years
• Right-handedness
• Written informed consent

Exclusion Criteria

• Pregnancy
• Neurological or psychiatric diseases (e.g. epilepsy, stroke, depression, anxiety disorders)
• Severe general illnesses (e.g. tumors, diabetes)
• Skin diseases (e.g. dermatitis, psoriasis or eczema)
• Current or recurrent pain
• Regular intake of medication
• Surgical procedures involving the head or spinal cord
• Head trauma followed by impairment of consciousness
• Past fainting spells or syncopes
• Metal (except titanium) or electronic implants
• Side-effects following previous electrical or magnetic stimulation
• Side-effects following previous thermal stimulation

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Transcranial alternating current stimulation (tACS)	10 Hz tACS of the bilateral somatosensory cortex	-
Transcranial alternating current stimulation (tACS)	80 Hz tACS of the prefrontal cortex	-
Transcranial alternating current stimulation (tACS)	10 Hz tACS of the prefrontal cortex	-
Transcranial alternating current stimulation (tACS)	Sham stimulation of the prefrontal cortex	-
Transcranial alternating current stimulation (tACS)	80 Hz tACS of the bilateral somatosensory cortex	-
Transcranial alternating current stimulation (tACS)	Sham stimulation of the bilateral somatosensory cortex	-

Primary Outcome Measures

Name	Time	Method
Changes in oscillatory brain activity before and after tACS application within each session	Measured immediately before and after the tACS protocol in each of six interventions (10 Hz tACS/80 Hz tACS/sham stimulation of the somatosensory/prefrontal cortex), which are separated by at least 24 hrs.	5-minute resting state electroencephalogram (EEG) will be recorded with two electrodes placed at the same electrode positions used for the respective tACS protocol. Power of oscillatory brain activity will be quantified in the alpha (8-12 Hz) and gamma (30-100 Hz) bands.
Changes in heart rate (BPM, beats per minute) between sessions	During 10 min thermal stimulation in each of six interventions (10 Hz tACS/80 Hz tACS/sham stimulation of the somatosensory/prefrontal cortex), which are separated by at least 24 hrs.	The electrocardiogram (ECG) will be recorded using two electrodes placed under the right clavicle and below the sternum, respectively.
Changes in pain rating on visual analogue scale (VAS; 0: 'no pain' to 10: 'maximal tolerable pain') between sessions	During 10 min thermal stimulation in each of six interventions (10 Hz tACS/80 Hz tACS/sham stimulation of the somatosensory/prefrontal cortex), which are separated by at least 24 hrs.	During thermal stimulation, participants will be instructed to continuously rate the currently perceived pain intensity using a finger-span device.
Changes in skin conductance responses (µS) between sessions	During 10 min thermal stimulation in each of six interventions (10 Hz tACS/80 Hz tACS/sham stimulation of the somatosensory/prefrontal cortex), which are separated by at least 24 hrs.	Skin conductance responses will be recorded using two electrodes attached to the index and middle finger of the left hand.

Secondary Outcome Measures

Name	Time	Method
Perception of tACS induced visual and skin sensations measured by numerical rating scale (NRS; 0: 'no sensation' to 10: 'very strong sensation')	Measured immediately after the EEG measurement following each of six interventions (10 Hz tACS/80 Hz tACS/sham stimulation of the somatosensory/prefrontal cortex), which are separated by at least 24 hrs.	The perception of visual and skin sensations induced by the tACS protocols will be assessed using a custom questionnaire.

Trial Locations

Locations (1)

Department of Neurology, Klinikum rechts der Isar, Technische Universität München; 🇩🇪 Munich, Bavaria, Germany