Researchers Investigate Origins of Consciousness in the Brain

WASHINGTON: Consciousness is fundamental to human existence, encompassing our ability to see, hear, dream, imagine, and experience a range of emotions like joy, pain, love, and fear. But pinpointing where this consciousness is located in the brain has puzzled scientists and medical professionals alike. A new study is shedding light on this complex issue.

In an effort to uncover the brain regions involved in consciousness, neuroscientists monitored electrical and magnetic activity, along with blood flow, in the brains of 256 participants across 12 laboratories in the U.S., Europe, and China. Their observations focused on brain activation while participants viewed various images.

The findings suggest that consciousness may not originate in the brain’s “intelligent” frontal regions, which have evolved throughout human history, but rather in the sensory areas at the back that handle visual and auditory processing.

“Why does this matter?” asked Christof Koch, a neuroscientist at the Allen Institute in Seattle and a lead author of the study published in Nature this week.

“Understanding the foundation of consciousness is vital for identifying who possesses it—adults, pre-verbal children, second-trimester fetuses, dogs, mice, squids, ravens, or flies. We need to uncover the underlying mechanisms in the brain for both theoretical and clinical reasons,” Koch explained.

During the study, participants were shown images of faces and objects.

“Consciousness is the sensation of seeing a drawing of a toaster or Jill’s face. It is separate from the actions linked to that sensation, such as pushing a button or saying, ‘I see Jill,'” Koch noted.

The research examined two prevailing theories about consciousness:

• **Global Neuronal Workspace Theory:** Proposes that consciousness arises in the brain’s frontal areas, where crucial information is then disseminated throughout.
• **Integrated Information Theory:** Suggests that consciousness emerges from the collaboration and communication between different brain regions as they collectively process information.

However, the study’s results did not support either theory.

“Where are the neuronal indicators of consciousness found in the brain? Are they placed in the frontal cortex, like the prefrontal cortex, as the Global Neuronal Workspace Theory proposes?” Koch asked.

The prefrontal cortex is critical in distinguishing humans, facilitating complex cognitive functions such as planning, decision-making, reasoning, and social behavior regulation.

“Or do these indicators lie within the posterior cortex, where hearing and vision processes take place?” he continued. “The evidence strongly favors the posterior cortex. If information related to conscious experience could not be identified at the front, or was significantly weaker there, it supports the notion that while frontal lobes are essential for intelligence and reasoning, they are not central to visual perception itself,” Koch stated.

Nevertheless, the research did not provide sufficient evidence of enduring connections in the back of the brain to validate the Integrated Information Theory.

Understanding how consciousness operates in the brain has practical implications.

Koch mentioned it could improve how doctors manage patients in comas, vegetative states, or those exhibiting unresponsive wakefulness due to conditions like traumatic brain injury, strokes, or drug overdoses.

“If a patient remains in this unresponsive state beyond a few days with no signs of recovery, the clinical team typically discusses whether this aligns with the patient’s wishes,” Koch remarked.

Of such patients, 70% to 90% pass away following decisions to discontinue life-supporting treatment.

“However, it’s now known that roughly a quarter of patients in comas or vegetative states may retain a form of consciousness—covert consciousness—yet cannot communicate this, as referenced in research published last year in the New England Journal of Medicine. Understanding the indicators of consciousness in the brain will enable us to better identify this hidden form of awareness,” Koch concluded.