Brain Wiring Upends Leading Consciousness Theories

When you’re looking at your phone, your visual neurons talk directly to your frontal cortex, creating a bridge between perception and higher cognition. This key finding from a landmark seven-year experiment challenges our understanding of consciousness, suggesting neither of two dominant theories fully explains how our sense of awareness arises.

A team of over 200 scientists across multiple institutions conducted what they call an “adversarial collaboration” – deliberately pitting competing theories against each other through experiments involving 256 human participants monitored with three different brain imaging technologies. This unprecedented approach aimed to reduce confirmation bias in consciousness research, a field where researchers often interpret data to support their preferred theory.

“Convergence on a broadly accepted neuroscientific theory of consciousness will have profound medical, societal and ethical implications,” the research team writes in their paper published Wednesday in Nature.

The study tested two leading theories: Integrated Information Theory (IIT), which proposes consciousness emerges from integrated information processing primarily in posterior brain regions, and Global Neuronal Workspace Theory (GNWT), which argues consciousness requires information broadcasting to frontal brain areas.

Participants viewed images while researchers measured brain activity using fMRI, magnetoencephalography, and intracranial electroencephalography. The experiment focused on what happens in the brain when we consciously perceive something – specifically how information about categories (faces vs. objects), orientations, and identities is processed and maintained.

The results revealed significant challenges to both theories. For IIT, researchers failed to find the predicted sustained synchronization within posterior brain regions. For GNWT, they found no evidence of the predicted “ignition” of activity in the prefrontal cortex when stimuli disappeared, and certain aspects of conscious perception weren’t represented in prefrontal areas.

“For IIT, the lack of sustained synchronization within posterior cortex contradicts the claim that network connectivity specifies consciousness,” the researchers note. “GNWT is challenged by the general lack of ignition at stimulus offset and limited representation of certain conscious dimensions in the prefrontal cortex.”

Dr. Christof Koch, a meritorious investigator at the Allen Institute involved in the project, described the research as addressing “one of the biggest, and most long-standing, intellectual challenges of humanity: the Mind-Body Problem.”

The findings have potential clinical implications for diagnosing covert consciousness in unresponsive patients. If consciousness depends more on sensory processing than previously thought, new techniques might better detect awareness in people with disorders of consciousness.

The seven-year project began at a 2018 workshop at the Allen Institute, bringing together competing theoretical camps to design and implement experiments together, an approach Koch says could benefit many scientific fields.

“The bio-medical field could hugely profit by ‘friendly’ competition among theories,” Koch said. “But it requires a great deal of cooperation and work.”

Professor Anil Seth of the University of Sussex noted that despite the challenge to both theories, the collaboration remains valuable: “Much has been learned about both theories and about where and when in the brain information about visual experience can be decoded from.”

Rather than declaring a winner, the study highlights the need for more refined theories. The researchers suggest moving toward a quantitative framework for systematically testing and developing theories of consciousness, emphasizing that scientific progress often involves cycles of challenge and refinement rather than simple verdicts.

The research suggests consciousness may be more about sensory processing and perception than higher-order thinking, with the study revealing important functional connections between visual brain areas and frontal regions. This raises fundamental questions about the relationship between perception, awareness, and cognition that future research will need to address.

While the adversarial experiment didn’t crown a definitive winner in the theoretical contest, it has significantly advanced our understanding of the neural basis of consciousness and established a powerful new model for scientific collaboration.