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Network theory sheds new light on origins of consciousness

by | Mar. 9, 2015, 1:00 PM | Want more research news? Subscribe to our weekly newsletter »

Illustration of brain showing connection that appear during awareness.

The black dots correspond to the 264 areas of the cerebral cortex that the researchers probed, and the lines correspond to the increased strength of the functional connections between each of these brain areas when subjects consciously perceive the target. The "hotter" colors are associated with stronger connections. This figure illustrates that awareness of the target corresponds to widespread increase in the strength of functional connections (Marois / Godwin).

Where in your brain do you exist? Is your awareness of the world around you and of yourself as an individual the result of specific, focused changes in your brain, or does that awareness come from a broad network of neural activity? How does your brain produce awareness?

Vanderbilt University researchers took a significant step toward answering these longstanding questions with a recent brain imaging study, in which they discovered global changes in how brain areas communicate with one another during awareness. Their findings, which were published March 9 in the Proceedings of the National Academy of Sciences, challenge previous theories that hypothesized much more restricted changes were responsible for producing awareness.

Rene Marois standing outdoors

Rene Marois (John Russell / Vanderbilt)

“Identifying the fingerprints of consciousness in humans would be a significant advancement for basic and medical research, let alone its philosophical implications on the underpinnings of the human experience,” said René Marois, professor and chair of psychology at Vanderbilt University and senior author of the study. “Many of the cognitive deficits observed in various neurological diseases may ultimately stem from changes in how information is communicated throughout the brain.”

Using graph theory, a branch of mathematics concerned with explaining the interactive links between members of a complex network, such as social networks or flight routes, the researchers aimed to characterize how connections between the various parts of the brain were related to awareness.

“With graph theory, one can ask questions about how efficiently the transportation networks in the United States and Europe are connected via transportation hubs like LaGuardia Airport in New York,” Douglass Godwin, graduate student and lead author on the research, said. “We can ask those same questions about brain networks and hubs of neural communication.”

Modern theories of the neural basis of consciousness fall generally into two camps: focal and global. Focal theories contend there are specific areas of the brain that are critical for generating consciousness, while global theories argue consciousness arises from large-scale brain changes in activity. This study applied graph theory analysis to adjudicate between these theories.

The researchers recruited 24 members of the university community to participate in a functional magnetic resonance imaging (fMRI) experiment. While in the fMRI scanner, participants were asked to detect a disk that was briefly flashed on a screen. In each trial, participants responded whether they were able to detect the target disk and how much confidence they had in their answer. Experimenters then compared the results of the high-confidence trials during which the target was detected to the trials when it was missed by participants. These were treated as “aware” and “unaware” trials, respectively.

Comparison of aware and unaware trials using conventional fMRI analyses that assess the amplitude of brain activity showed a pattern of results typical of similar studies, with only a few areas of the brain showing more activity during detection of the target than when participants missed seeing it. The present study, however, was interested not simply in what regions might be more activated with awareness, but how they communicate with one another.

Unlike the focal results seen using more conventional analysis methods, the results via this network approach pointed toward a different conclusion. No one area or network of areas of the brain stood out as particularly more connected during awareness of the target; the whole brain appeared to become functionally more connected following reports of awareness.

“We know there are numerous brain networks that control distinct cognitive functions such as attention, language and control, with each node of a network densely interconnected with other nodes of the same network, but not with other networks,” Marois said. “Consciousness appears to break down the modularity of these networks, as we observed a broad increase in functional connectivity between these networks with awareness.”

The research suggests that consciousness is likely a product of this widespread communication, and that we can only report things that we have seen once they are being represented in the brain in this manner. Thus, no one part of the brain is truly the “seat of the soul,” as René Descartes once wrote in a hypothesis about the pineal gland, but rather, consciousness appears to be an emergent property of how information that needs to be acted upon gets propagated throughout the brain.

“We take for granted how unified our experience of the world is. We don’t experience separate visual and auditory worlds, it’s all integrated into a single conscious experience,” Godwin said. “This widespread cross-network communication makes sense as a mechanism by which consciousness gets integrated into that singular world.”

Robert Barry, a research fellow in radiology and radiological sciences, was a co-author on the research. The research was funded by the National Institutes of Health (NIH) P30-EY008126 grant to the Vanderbilt Vision Research Center and NIH grant 5R01EB000461.

Media Inquiries:
Melanie Moran, (615) 322-NEWS
melanie.moran@vanderbilt.edu


  • This is very much in line with Stanislas Dehaene’s global neuronal network theory. Information which is conscious is broadcasted.

  • drawsprocket

    Quantum mechanics says nothing about neuroscience and vice versa. If you bring quantum mechanics into this discussion, you haven’t even read the article.

    • Smacker

      Depends on what sources you read and this article is not the final word.

      Pribram, Kak, Henry Stapp or Stuart Hameroff are some of those who invoke(d)/use(d) quantum mechanics theory in their research in the field of neuroscience.

    • Peter

      There are many biological processes that cannot be fully understood without quantum mechanics and consciousness is one of them.

  • Mike Kiech

    Conciousness may be clarified in swarm theory research.

  • Logo & Shibboleth

    Like the OSI model in computing, consciousness resides at the Application layer, derived from the layers below. Makes perfect sense. Until rendered as the final product, no one would recognize a line of Photoshop code either. Its the emergent result and experience of using a program as opposed to looking at hardware and scripts.

  • Giuseppe Corbelli

    This seems to be in perfect accordance with Edelman and Tononi “dynamic core hypothesis”, giving account for both integration and complexity of large and distributed neuronal assemblies.
    This field is extremely interesting. I thought I’ve studied it deeply for my dissertation, yet it’s as vast as universe itself!

  • Rob Roberts

    the problem with linking quantum mechanics to consciousness is that quantum theories have had so much quackery linked to them for the last few generations. When guys like Chopra and such start claiming that mind has control over reality and link it to quantum theories it deflates any scientific study. They try and link things like paranormal phenomenon to quantum theories and come off looking like nutjobs.

  • Timothy Busbice

    From my own connectomic research, I suggest that the recurrent nature of the network is highly responsible for what we perceive as consciousness. Studying the nematode nervous system, we see recurrent connections back to any given neuron grows exponentially the deeper the network layers. This aspect of connectomics is overlooked consistently.

  • pondrthis

    Too bad fMRI is not a quantitatively sound protocol. You take the differences of differences of ratios (differences in R2*) of highly accelerated (usually EPI) SNR-limited (as all NMR) data. That’s basically data analysis Hell. And then you make statistical inferences in a cyclic fashion (use the given data to identify areas to test, rather than blindly test areas in a multivariate manner), as noted by statisticians in many highly critical papers.

    I can’t take fMRI seriously anymore.

    • Rene Anand

      Thanks for pointing out the fMRI debacle!

      • pondrthis

        You might enjoy one particularly humorous diatribe against standard fMRI practices: it’s a winner of an IgNobel Prize. “Neural Correlates of Interspecies Perspective Taking in the Post-Mortem Atlantic Salmon: An Argument For Proper Multiple Comparisons Correction” by Craig Bennett.

        They find that a dead salmon is able to recognize the emotional state of various human beings displayed in still-frame images when using standard fMRI statistics. They then provide correct protocols in order to avoid spurious false-positives.

  • brantc

    Consciousness is in the (kinetic energy) field surrounding the human body. It interfaces to the brain through phase modulation of the London Moment paired electrons in the microtublues of the brains.

    The human body could almost be thought of as a tele presence interface for consciousness….

  • Peter

    Consciousness is not a product of information being shuttled around in just the right way. All the programming in the world can not make self aware consciousness arise from a piece of hardware.

    • InvictaBellum

      Not yet…

  • mrfloopa

    So once was psychology.

  • mrfloopa

    Without understanding the intricacies of a computer, we would not be able to build upon and improve them. Nanotechnology works on the atomic scale, and quantum computers rely on an understanding of quantum events in order to take advantage of them, which then inform the higher level processes.

    We have to rely on a top-down approach to understand the brain and consciousness, but that doesn’t mean we should assume we’ve reached the bottom. Paradigm shifts in science happen all the time, but only when somebody keeps an open mind.

  • Andrea Faré

    I believe consciousness is just a by product of the Encephalization quotient, when a neural network is big enough with respect to the amount of input it has to control, it will assign the concept of “presence of own body and sensory habilities to experiences” to a variable and recall that variable whenever it is handy (many times since it is more efficient than re building all the necessary correlations). We have it, some animals in different flavours have it (the European Magpies representing probably the border in animal life where conscience emerges) . I am strongly convinced that Consciousness will emerge in any sufficiently complex neural network with sensory input with some motivation to survive and explore a complex environment, given enough time needed to make the aforementioned variable assignement.

    • Rene Anand

      Like your premise!

  • Joseph Salmon

    Please inform me fully about the most ambitious research with the co nsciousness study. Sinceely, jsalmon403@gmail.com

  • Shashiendra

    Your point of view is relevant in scenarios where science has reached some basic understanding of the concept in question. Consciousness has neither been seen or touched – it is intangible ; at-least for the present ; and hence the speculation of its relationship with quantum mechanics.

  • Hungle Jut

    Once again there is an assumption that there is a conciousness to be uncovered. It is not a new idea that the self is a lie the mind tells itself, but it seems to be forgotten. I wonder why this assumption is not questioned at all, since all resulting research becomes moot. What they seem to suggest (I might have gotten this wrong) is that someone who is deaf, blind, or missing part of the brain (congenital or through trauma) are missing part of their conciousness. I want to point towards split-brain syndrome as a counter (Corpus Callosum is severed, removing communication between the hemispheres), since “conciousness” was not split, only the ability to distinguis and name items, ie the brain-tools.

    • Rene Anand

      Excellent!

  • Rene Anand

    Most brain diseases are the result of something more simple. Genes that are not expressed properly due to their dysregulation as a result of either an inherent genetic variant or due to an environmental factor or both. The consequences are propagated at the molecular, cellular, synaptic and circuit level. One doesn’t need to invoke sophisticated “consciousness” or network ideas to understand or treat these diseases.

    A very important question that has not be adequately addressed from my standpoint: where in the brain do memories reside? What neurobiological mechanism can STABLY store memories for decades, yet allow recall to occur in about 100 milliseconds? The double constraint, labile and stable restricts possible explanations that then have to be experimentally verified. There are a lot of very smart folks on this blog, hoping one of them can answer this question before we delve into consciousness or cognition!