In the realm of network science, researchers study a mechanism known as “explosive synchronization,” or ES, in which a network has an outsized reaction to a regular-sized disturbance. The “network,” in this context, could mean a computer, an electrical grid, even a social network—or, we’ve now learned, a brain.
In a striking crossover from physics to medicine, an international team of physicists, neuroscientists, anesthesiologists and chronic pain researchers collaborated to apply network science to the study of fibromyalgia, a common but poorly understood disorder of which the defining symptom is chronic pain with no obvious cause. (It’s what recently caused Lady Gaga to cut her world tour short.)
The team took electroencephalograms, better known as EEG readings, from 10 female patients (fibromyalgia is more common in women than in men). They found that the patients’ baseline level of pain sensitivity was unusually heightened, despite the absence of any apparent stimuli to cause it.
To the researchers’ surprise, their patients proved hypersensitive to all kinds of stimuli (like visual or auditory) besides pain, suggesting they had a clinical predisposition to heightened responsiveness across the board. The team discovered that among chronic pain patients, the brain’s neural network showed ES characteristics—reacting to minor or seemingly non-existent stimuli with an explosion of pain, the same way a small power surge can trip an electrical network and cause a blackout. A paper describing the research was published in the journal Scientific Reports.
“If you were to touch my hand, that wouldn’t be a stimulus that would have repercussions for me,” co-author George Mashour, Director of the Center for Consciousness Science at the University of Michigan, told Newsweek. “But for a chronic pain patient, even what would be considered an innocuous stimulus like touch can be registered as pain.”
The team is the first to show that a hypersensitive brain can act like an ES network, and that conclusion raises a complex question: Could chronic pain be a consciousness disorder, rather than a physical one?
When you shut your hand in a door or cut yourself shaving, your pain has an intuitive source. But for patients with conditions like fibromyalgia, the experience of pain might not be comparable to the one most of us have, Mashour said. Instead, such patients might experience chronic pain closer to the way patients with schizophrenia experience hearing voices. In other words, it looks like fibromyalgia-beset muscles don’t ache because anything is hurting the muscles themselves; the pain originates in the brain. The call is, as they say, coming from inside the house.
“That doesn’t mean it’s not a real experience—it is,” Mashour said. “It’s interesting to think about certain dimensions of pain as being a kind of hallucination, and as a way of gaining more insight into consciousness.”
Pain is inherently a state of consciousness, Mashour explained; it’s defined by what you feel when you’re experiencing it. On the other side of the same coin is nociception, which refers to an unpleasant stimulus being physically processed by your nervous system. Think about it in terms of being anesthetized and unconscious—your body still experiences nociception, even though you no longer register the pain as a feeling.
As it happens, anesthesia was what allowed the team to pursue their research. ES is an underlying mechanism of what’s known as a state transition—the process by which a brain ramps up its level of consciousness, like when it reboots after general anesthesia.
Hypersensitivity isn’t a condition of normal consciousness. But when the brain is in that fragile transition state, just barely across the line from conscious to unconscious, it’s extra sensitive to small disturbances—the way the brain of a chronic pain patient is all the time. Maybe, the researchers theorized, an ES-fueled state transition could mean not just a shift from unconsciousness to normal, waking consciousness, but from normal, waking consciousness to a state of elevated pain.
While there are certain pain-relieving drugs approved for treating fibromyalgia, the condition has no cure. In physics, however, an ES network can be converted into a non-ES network. The brain is way too complex for this to translate immediately to a practical solution—but, by pursuing treatment options through the lens of network science, it does leave room for a theoretical one.This article has been updated with the correct name of the journal in which the study was published. It is Scientific Reports (a Nature journal), not Nature.
via-newsweek.com and disabilitytoday.co.uk