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.

Trial Health

On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment

participants targeted

Target at P25-P50 for not_applicable

Timeline

Completed

Started Apr 2019

Shorter than P25 for not_applicable

Geographic Reach

1 country

1 active site

Status

completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

6 months study duration

First Submitted

Initial submission to the registry

January 10, 2019

Completed

6 days until next milestone

First Posted

Study publicly available on registry

January 16, 2019

Completed

3 months until next milestone

Study Start

First participant enrolled

April 15, 2019

Completed

6 months until next milestone

Primary Completion

Last participant's last visit for primary outcome

October 23, 2019

Completed

Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

October 23, 2019

Completed

Last Updated

June 4, 2020

Status Verified

June 1, 2020

Enrollment Period

6 months

First QC Date

January 10, 2019

Last Update Submit

June 2, 2020

Conditions

Experimental Pain in Healthy Human Subjects

Keywords

paintACSalphagammaneural oscillationsbrain

Outcome Measures

Primary Outcomes (4)

Changes in pain rating on visual analogue scale (VAS; 0: 'no pain' to 10: 'maximal tolerable pain') between sessions
During thermal stimulation, participants will be instructed to continuously rate the currently perceived pain intensity using a finger-span device.
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.
Changes in skin conductance responses (µS) between sessions
Skin conductance responses will be recorded using two electrodes attached to the index and middle finger of the left hand.
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.
Changes in heart rate (BPM, beats per minute) between sessions
The electrocardiogram (ECG) will be recorded using two electrodes placed under the right clavicle and below the sternum, respectively.
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.
Changes in oscillatory brain activity before and after tACS application within each session
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.
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.

Secondary Outcomes (1)

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.

Study Arms (1)

Transcranial alternating current stimulation (tACS)

EXPERIMENTAL

Device: 10 Hz tACS of the bilateral somatosensory cortexDevice: 10 Hz tACS of the prefrontal cortexDevice: 80 Hz tACS of the bilateral somatosensory cortexDevice: 80 Hz tACS of the prefrontal cortexDevice: Sham stimulation of the bilateral somatosensory cortexDevice: Sham stimulation of the prefrontal cortex

Interventions

10 Hz tACS of the bilateral somatosensory cortexDEVICE

10 Hz tACS at 1 mA will be applied over the bilateral somatosensory cortex for 10 minutes using a Neuroconn stimulator (DC-Stimulator MR; Neuroconn, Ilmenau, Germany) and 2 5\*5 cm rubber electrodes placed at electrode positions CP3 and CP4 according to the international 10-20 system.