Chronic pain linked to distinctive patterns of brain activity

Better understanding the brain patterns linked to persistent pain could open the door to new treatments

By Obomate Briggs

22 May 2023

An X-ray of one study participant, showing implanted electrodes (red) connected to recording implants

Prasad Shirvalkar

Signatures of electrical activity have been identified in the brains of people with chronic pain. Although a small study, the discovery could one day lead to more effective treatments.

Chronic pain, which lasts longer than 3 months, affects more than 30 per cent of the world’s population, with existing therapies often having limited effectiveness. To help in the development of new treatments, Prasad Shirvalkar at the University of California, San Francisco, and his colleagues set out to better understand how the brain regulates pain.

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The team implanted electrodes and stimulators into the brains of four people with chronic pain as a result of a stroke or amputation. These recorded electrical activity in the brain regions that have been associated with the potentially long-term emotional and cognitive aspects of pain – the orbitofrontal cortex (OFC) and the anterior cingulate cortex (ACC) – which the researchers anticipated are more involved in chronic discomfort than some other brain regions that have been linked to short-lived pain.

Over the next three to six months, the participants answered surveys on the severity of their pain multiple times a day. After reporting this, they pressed a button that took a 30-second recording of the activity in their OFC and ACC.

Machine learning then linked these electrical signals to the participants’ self-reported pain severity. From this, the researchers identified neural patterns that indicated whether the individual was experiencing a high or low pain state, acting as a biomarker for different levels of discomfort.