Summary: Researchers at the University of Michigan have identified what part of the brain is responsible for making people consciously aware of some signals and not other similar signals.
Original author and publication date: Study Find – August 7, 2021
Futurizonte Editor’s Note: Discoveries like the one presented hear highlight the need for a deeper understanding of neuroscience and neurophenomenology.
From the article:
When a person is awake, their brain is flooded with an almost constant flow of information from the body’s five senses. The brain immediately sorts through the information and, depending on how strong the sensory signals are, decides whether it should be treated consciously. Why the brain makes people consciously aware of some signals when others of similar strength are processed unconsciously has been a mystery for decades. Researchers at the University of Michigan have identified what part of the brain is responsible for making this call.
“Information processing in the brain has two dimensions: sensory processing of the environment without awareness and the type that occurs when a stimulus reaches a certain level of importance and enters conscious awareness,” explains study author Dr. Zirui Huang, a research investigator in the university’s Department of Anesthesiology, in a statement.
The researchers wanted to see whether the unconscious-conscious switch occurred in a part of the brain called the anterior insular cortex. Participants were placed inside a functional magnetic resonance imaging (fMRI) machine and given Propofol, an anesthetic, to control their level of consciousness. They were then asked to imagine themselves playing tennis, walking down a path, or squeezing their hand. At the same time, they were asked to squeeze a rubber ball as they gradually lost consciousness and regained it, once the drug had worn off.
Mental imagery, or imagining things, produces similar brain activity as performing the tasks in real life, previous studies have found. When participants pictured themselves playing tennis, part of the brain responsible for controlling movement lit up.
Other areas of the brain remained “deactivated” during this time, as mental activity was focused on the imagined task at hand. But as participants began to lose consciousness, deactivation became less frequent and once they had passed out, their brains did not respond to mental imagery. In contrast, as they regained consciousness, some activity returned, until they were wide awake and their brains were firing on all cylinders. The anterior insular cortex played a role in the successful switch between these activations and deactivations, the researchers found.
“A sensory stimulus will normally activate the anterior insular cortex,” explains study co-author Dr. Anthony Hudetz. “But when you lose consciousness, the anterior insular cortex is deactivated and network shifts in the brain that support consciousness are disrupted.”