Neural Mechanisms of Light Driven Analgesia

Part of paid clinical trials in Chapel Hill, North Carolina.

Sponsor
University of North Carolina, Chapel Hill
Study ID
NCT07245303
Status
Recruiting
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Conditions

  • Fibromyalgia
  • Healthy Controls Group - Age and Sex-matched
  • Musculoskeletal Pain

Eligibility Criteria

Sex
ALL
Age
18 Years - N/A
Healthy Volunteers
Accepted

Interventions

  • S-cone modulating visual stimulus — OTHER
    The investigators will deliver a uniform wide-field, S-cone modulating stimulus via a fiberoptic, MRI-safe visual stimulator. This stimulus approximates the appearance of white but modulates the S-cone, driving the S-ON and S-OFF pathways by alternating two lights at 19 Hz using a mixture of light emitting diodes (LEDs), including those embedded in our stimulus with spectral peaks of 405, 565, and 660 nm. This stimulus will differentially activate the S-cones where, between the two phases the ratio of S-cone activity is 100. The frequency alternating between the two lights, 19 Hz, was chosen because retinal ganglion cells in the retina still respond robustly but above the cortical perceptual flicker detection threshold.
  • Equal Energy White Visual Stimulus — OTHER
    The investigators will deliver a uniform wide-field, equal-energy light stimulus via a fiberoptic, MRI-safe visual stimulator. This will serve as a reference condition in which chromatic opponency has been eliminated. This stimulus ensures that the quantal catch of each cone photoreceptor (S-, M- and L-) is held constant using a mixture of LEDs, including those embedded in our stimulus with spectral peaks of 405, 565, and 660 nm. The stimulus will modulate to nearly approximate the appearance of the S-cone modulating light.
  • Green light visual stimulus (S-OFF) — OTHER
    The investigators will deliver a uniform wide-field, green light modulating stimulus via a fiberoptic, MRI-safe visual stimulator. Static Green (565 nm) Light presented via MRI compatible light guides.
  • Evoked Pressure Pain Stimulus — OTHER
    The pressure in which a rapid inflation cuff positioned over the left gastrocnemius achieves a pain severity of 40 where 0 is "no pain" and 100 is the "worst pain imaginable will be determined pre-scan and applied during the entire functional imaging acquisition to evoke a deep pressure pain.

Study Details

The goal of this study will be to understand the biological mechanisms that are responsible to light-driven analgesia. Light presented to the retina has been shown to have pain relieving properties in pre-clinical and clinical studies. In this study the investigators will evaluate the functional connectivity between subcortical visual areas and non-image forming brain areas that are involved in pain sensation. The investigators will also evaluate how three colored light stimuli presented to the retina results in changes in whole brain evoked activation patterns in participants with chronic musculoskeletal pain and in healthy controls. The investigators will also assess while brain evoked activation patterns in response to a pressure pain stimulus in the presence of three light stimuli in individuals with chronic musculoskeletal pain and healthy controls.

Key Dates

Start date
Feb 24, 2026
Status verified
May 2026
Primary completion
Jan 31, 2030
Completion
Jan 31, 2030

Study Design

Enrollment
60 participants (estimated)
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
OTHER

Arms

  • Experimental: Light sequence during imaging
    The sequence of stimulus presentation for resting state scans will be Equal Energy White (with luminance modulation) for 8 minutes then Static Green for 8 minutes, followed by an anatomical scan, then S-cone modulating stimuli for 8 minutes.

Primary Outcome Measure

Resting State Functional Connectivity-seed Voxel Analysis in Participants with cMSP and Healthy Controls [ Time Frame: During 8 minute resting state scan as part of the ~1 hour scanning session ]

Central Contacts

Locations (1)

FacilityCityStateZIPSite coordinators
University of North Carolina at Chapel HillChapel HillNorth Carolina27599
Matthew Mauck, MD, PhD
[email protected]
919-966-5136
Matthew Mauck, MD, PhD (PRINCIPAL_INVESTIGATOR)

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By research site
University of North Carolina at Chapel Hill· Chapel Hill, NC

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