General anesthesia reduces uniqueness of brain's functional 'fingerprint,' study finds
Baku, April 12, AZERTAC
Past psychology research suggests that different people display characteristic patterns of spontaneous thought, emotions and behaviors, according to Medical Xpress. These patterns make the brains of distinct individuals unique, to the point that neuroscientists can often tell them apart based on their neural activity.
Researchers at McGill University, University of Cambridge and other institutes recently carried out a study aimed at investigating how general anesthesia influences the unique neural activity signatures that characterize the brains of different people and animals.
Their findings, published in Nature Human Behavior, show that general anesthesia suppresses each brain's unique functional connectivity patterns (i.e., the connections and communication patterns between different regions of the brain), both in humans and other species.
"Every person is unique, they think and feel and act in unique ways," Andrea Luppi, first author of the paper, told Medical Xpress. "This uniqueness comes from our brain. The way that areas of the brain interact with each other is unique to each individual: it can be used like a 'brain fingerprint.'
"But when you lose consciousness, for example during deep sleep, your sense of being 'you' is gone. So, our question was: what happens to brain fingerprints when we lose consciousness, such as during the artificial sleep induced by general anesthesia? "
To explore the effects of anesthesia on the brain's functional connectivity patterns, Luppi and his colleagues employed an imaging technique commonly used in neuroscience research called functional magnetic resonance imaging (fMRI). This technique allows neuroscientists to monitor the activity of different brain regions over time and non-invasively, by measuring changes in blood flow.
"We collected fMRI scans from healthy human volunteers before general anesthesia, then when they were unconscious because of the anesthesia, and then again after they recovered consciousness," explained Luppi. "For each scan, we measured 'functional connectivity': a representation of how brain regions interact. We used this functional connectivity to obtain 'brain fingerprints,' telling us how easy or difficult it is to tell people apart based on their brain activity."
Interestingly, the fMRI scans collected by the researchers showed that the brain activity of people while they were under the influence of anesthesia was suppressed. In fact, anesthesia made people almost impossible to tell apart from each other solely by examining their brain activity, which was possible when they were still conscious.
"In contrast, using brain fingerprints it is very easy to tell people apart when they are conscious," said Luppi. "This effect is not uniform in the brain: it is strongest in the parts of the brain that are uniquely human and mostly distinguish us from other species. The implication is that just as your own conscious experience is unique to you, so are the brain patterns that support it. When consciousness is gone, people's brain activity is also less unique."
Luppi and his colleagues gathered interesting new insights about the effects of general anesthesia on the brain and its unique patterns of neural activity. In the future, the results of their study could inspire further cross-species research looking at the brain before, during and after the administration of anesthetics, which could in turn inform the development of interventions to facilitate the rehabilitation of both people and animals after medical procedures that require anesthesia.
"I am very interested in comparisons between humans and other species," added Luppi. "Anesthesia is very conserved across species, so we can learn a lot from them about how anesthesia works on the brain. Ultimately, I hope that by learning how the brain reboots consciousness after anesthesia, we can learn how to help recovery of consciousness in patients who suffer from coma and other forms of chronic unconsciousness after a brain injury."
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