Human consciousness, the lens through which we experience life, is a hard thing to pin down in the brain — especially in people who have experienced traumatic brain injury and can’t tell us that their brains are still executing that essential function.
New research released in Science Advances takes a big step forward in identifying brain patterns that act as clues to whether someone may still be experiencing consciousness, even if they can’t tell us themselves.
Scientists hope that by identifying these brain patterns, they may one day be able to help unresponsive patients regain consciousness.
This paper, first-authored by cognitive and clinical neuroscientist Athena Demertzi, Ph.D., is based on existing theories about how the brain produces consciousness. Consciousness, on some level, seems to be associated with brain connectivity. When we’re unconscious, previous studies indicate that regions of the brain turn inward, decreasing communication efforts with other, far-flung regions. When we’re tripping on LSD, the brain produces different types of connectivity, sending lots of signals among regions, a phenomenon that some explain as “altered consciousness”.
But during simple, sober consciousness, the brain steadily sends signals among brain regions and creates an experience of life that is far greater than the sum of its parts.
This paper identifies distinct patterns of brain activity associated with consciousness, which may help illuminate when unresponsive patients are actually switching between conscious and unconscious states:
“Working with families and patients’ caregivers all these years I realize that there is a constant demand for information on what’s happening with their beloved one,” Demertzi tells Inverse. “I consider the clinical relevance of our current findings promising to provide information about the state of consciousness in patients, yet I find they merit further validation before we use them as a clinical biomarker.”
Working from the University of Liége in Belgium, Demertzi began her investigation by taking fMRI images from 159 people, including healthy individuals, people under anesthesia, and patients with unresponsive wakefulness syndrome — a vegetative state in which someone’s eyes are open, but they show no signs of awareness. Demertzi analyzed the activity and connectedness of 42 different brain regions to illuminate the patterns. Overall, she identified four different patterns but found that two seem to be the most useful for determining consciousness.
The first of these is pattern one, which she describes as “the most complex pattern in terms of richness in the way regions communicate with each other.” Pattern one, she explains, is indicative of consciousness in healthy brains. The other pattern she noticed was pattern four, a “low coherence” pattern, meaning that the 42 regions she was tracking weren’t communicating very well. Pattern four, she suggests, indicated unconsciousness (it was commonly found in people under anesthesia) — which fits well with previous findings.
The new part about Demertzi’s study is that she noticed that some unresponsive patients tend to switch from the unresponsive pattern four to the highly responsive pattern one — even for the briefest of seconds.
Source: inverse.com