Neural Mechanisms of Light Driven Analgesia

The investigators will recruit 30 participants with chronic musculoskeletal pain (cMSP) and 30 healthy, matched controls. Participants will undergo a comprehensive assessment of important covariates that influence pain experience. Individuals will then undergo quantitative sensory testing that will be used to psychophysically assess pain sensitivity and conditioned pain modulation (CPM) immediately prior to the scanning session. Individuals will then undergo fitting of a rapid inflation pressure cuff on the left calf to achieve the same level of pain among each participant (who may have different pain sensitivity). Once these settings are established, participants undergo MRI scanning per the protocol described below. Following each scan block, a brief pain assessment will be performed to determine pain severity (0-100 visual analog scale) to serve as a covariate for our proposed analyses (as pain can change over the course of imaging) and will enable correlation of BOLD signal change to pain in exploratory analyses designed to validate our mechanistic discoveries. The imaging data will then be pre-processed to ensure data quality and assurance and then analyzed to determine the functional connectivity and the evoked brain activation patterns.

Inclusion criteria

for participants with cMSP and healthy controls (n=30)

• Adults ≥18 years of age.
• Individuals who do not have any plans for medication or treatment changes for the next 3 months.
• Participants must be willing and able to undergo an MRI.
• Participants must not be claustrophobic
• Participants must be alert and oriented and able to provide informed consent.
• Individuals must be able to speak and read English.

Inclusion criteria

for participants with cMSP only (n=30)

• To be eligible, participants must have a score of ≥7 on the Widespread pain index (WPI) and ≥5 on the symptom severity scale (SSS), or 4-6 on the WPI and ≥9 on the SSS in the 2016 Fibromyalgia Questionnaire.
• Pain symptoms must have been present for 3 months or longer.
• Pain must be present in 4 out of 5 body regions.
• Individuals enrolled will have an average pain severity ≥4 on the 0-10 NRS over the month prior to enrollment to recruit individuals with moderate to severe chronic MSP.

Inclusion criteria

for Participants with Congenital Stationary Night Blindness (n=2)

-2 additional participants without chronic MSP will be recruited with diagnosed congenital stationary night blindness

Exclusion criteria

• Presence of retinal vision disorders or conditions resulting in vision impairment.
• Patient-reported photosensitivity, photophobia, or aversion (as may occur in autoimmune diseases such as systematic lupus erythematosus).
• Disorders including uveitis, cataracts, color-blindness, history of seizure disorder.
• Plans for analgesic treatment plan changes in next 3 months (surgery, analgesic medication changes, injections, pain procedures, etc).
• Prisoner Status.
• Pregnancy.
• Contraindications to MRI imaging. These include the presence of implanted/embedded ferromagnetic materials, implanted medical devices that are not MRI compatible, and claustrophobia.