Summary: Using neuroimaging, researchers identified three cortical gradients that correspond to distinct dimensions of consciousness.
Source: University of Michigan
Understanding what it means to be conscious goes beyond philosophy; it is an active scientific question about how subjective experience emerges from the brain’s activity.
How consciousness arises has direct clinical relevance: it affects how clinicians interpret and treat conditions ranging from coma—where a person is alive but unable to interact with the environment—to the reversible suppression of consciousness during surgical anesthesia, and the altered experiences and thought patterns seen in psychiatric disorders such as schizophrenia.
Contemporary research indicates that consciousness does not spring from a single brain location but instead emerges from interactions across widespread networks. Yet mapping the complex linkages between brain regions that generate the dimensions of awareness and wakefulness has remained challenging.
A new study leverages functional MRI (fMRI), which tracks brain activity through blood-flow changes over time, to offer a different way to describe and investigate conscious states.
“Consciousness is complex and studying it is like solving a scrambled Rubik’s cube,” said Zirui Huang, Ph.D., research assistant professor in the University of Michigan Medical School Department of Anesthesiology. “If you look at just a single surface, you may be confused by the way it is organized. You need to work on the puzzle looking at all dimensions.”
In this context, the key dimensions of consciousness include arousability (the brain’s capacity for wakefulness), awareness (the content of experience, such as perceiving the redness of a rose), and sensory organization (how sensory inputs are integrated into a coherent experience).
Until now, those dimensions were largely conceptual and lacked direct mappings to brain activity. In the present work, researchers led by Huang, George Mashour, M.D., Ph.D., and Anthony Hudetz, DBM, Ph.D., sought to find neurobiological counterparts to these dimensions by examining the brain’s functional geometry rather than treating the cortex as a collection of isolated, discrete regions.
A helpful analogy: traditional brain-mapping treats cortical areas like political borders on a map—clearly defined but somewhat arbitrary. By contrast, studying gradients or topography—akin to following mountain ranges—reveals continuous, natural relationships that better capture the brain’s functional organization.
Following this approach, the investigators examined cortical gradients—continuous patterns capturing how functional properties vary across the cortex—using fMRI recordings taken from people in a range of conscious states: awake, anesthetized, in coma, and individuals with psychiatric diagnoses such as schizophrenia.
From recordings spanning 400 distinct brain regions, the team organized activity patterns into gradient maps and compared how those gradients changed across different states. Their analyses revealed three major cortical gradients that appear to align with the conceptual dimensions of consciousness: arousability, awareness, and sensory organization.
“What used to be mapped only as a helpful diagram of conscious states might now be mapped in the brain itself,” said Hudetz, senior author on the study.
The study found that disruptions to consciousness—whether produced pharmacologically (anesthesia), neuropathologically (coma), or psychiatrically (certain mental illnesses)—were associated with selective degradations or reconfigurations of one or more cortical gradients. Those spatial reconfigurations correlated with altered dynamics in how brain states transitioned over time, linking the geometry of the cortex to observable changes in responsiveness and subjective experience.
Huang emphasized the potential clinical implications: mapping consciousness in this way could inform brain-based diagnostics or assessments for patients with neurological disorders, offering more nuanced measures of arousal, awareness, and sensory integration than current approaches.
“Our study opens a new view of the link between consciousness and the brain,” Huang said. George Mashour added, “This work represents an important contribution to the science of consciousness and aligns with our mission of achieving deeper understanding while advancing clinical care.”
About this consciousness research news
Author: Kelly Malcom
Source: University of Michigan
Contact: Kelly Malcom – University of Michigan
Image: The image is in the public domain
Original Research: Open access. “Functional geometry of the cortex encodes dimensions of consciousness” by Zirui Huang et al., Nature Communications
Abstract
Functional geometry of the cortex encodes dimensions of consciousness
Consciousness is a multidimensional phenomenon, but key dimensions such as awareness and wakefulness have been described conceptually rather than neurobiologically. The authors hypothesize that dimensions of consciousness are encoded in multiple neurofunctional dimensions of the brain and analyze cortical gradients—continua that capture the brain’s overarching functional geometry—to characterize these dimensions.
The work demonstrates that disruptions of human consciousness—whether pharmacological, neuropathological, or psychiatric—are associated with degradation of one or more major cortical gradients depending on the state. Network-specific reconfigurations within the multidimensional cortical gradient space are linked to behavioral unresponsiveness from various causes, and these spatial reconfigurations align with a temporal disruption in the structured transitions of dynamic brain states.
Overall, the study provides a unifying neurofunctional framework for multiple dimensions of human consciousness in health and disease, suggesting new directions for research and potential clinical applications in diagnostics and monitoring of disorders that affect awareness and arousal.