Signature of consciousness captured in brain scans

Signature of consciousness captured in brain scans
2009 11 13

A telltale signature of consciousness has been detected that takes us a step closer to disentangling the brain activity underlying conscious and unconscious brain processes.

It turns out that there is a similar pattern of neural activity each time we become conscious of the same picture, but not if we process information from the image unconsciously. These contrasting patterns of activity can now be detected via brain scans, and could one day help determine if patients with brain damage are conscious. They might even be used to probe consciousness in animals.

"It's very exciting work," says neuroscientist Raphaël Gaillard of the University of Cambridge, who was not involved in the work. "The use of a reproducibility measure to disentangle conscious and non-conscious processes is genuinely new." Gaillard has previously shown that coordinated activity across the entire brain is one of the signatures of consciousness .

Consistent signals

So far, efforts to find a brain signature of consciousness have focused on the intensity of neural activity, how long it lasts, and whether signals tend to be synchronised across different regions of the brain.

"We were looking for something other than the intensity and duration of the neural activity that characterises conscious neural processing," says Aaron Schurger of Princeton University in New Jersey, who led the new work.

He and his colleagues hypothesised that when the brain is presented with the same sensory input – a picture, say – time after time, then conscious awareness of the picture should produce similar neural activity each time.

Conversely, if the sensory input did not enter conscious awareness, it should produce different brain activity each time because there would be other subconscious processes going on at the same time.

Invisible pictures

To test this hypothesis, Schurger and colleagues used functional magnetic resonance imaging (fMRI) to measure the brain activity in 12 volunteers who were asked to look at a series of images – some designed to elicit a conscious response, others a subconscious one.

The researchers invoked conscious processing simply by showing volunteers pictures of faces or houses. To invoke subconscious processing, the researchers presented volunteers with so-called "invisible stimuli".

These consist of two drawings, of either a house or a face, one shown to each eye. Crucially in each pair, one drawing is in pale orange on a pale green background, the other is the same drawing with the colours reversed. When the brain is confronted with such seemingly contradictory visual inputs it reconciles them by creating a yellow patch. So the volunteer consciously sees nothing but yellow, though the brain has subconsciously processed the face or house.

Probing anaesthesia

A set of fMRI recordings of subjects' temporal lobes backed up the team's hypothesis: each time a house or face was consciously processed by an individual, the resulting patterns in brain activity were similar. When the same image was processed subconsciously, the researchers found that the patterns of brain activity were much more variable. "Neural patterns were more reproducible when the drawings were seen consciously compared to when they were not," says Schurger.

The team thinks that reproducibility – the replication of similar neural patterns in the brain each time it becomes conscious of the same sensory input – gives us clues as to what consciousness is.

It could also be used in the future to tell if someone in a coma is conscious, or probe the consciousness of people under anaesthesia, something that also isn't well understood.

Article from: NewScientist.com

Image credit: HealthyJockey.com

Eldon Taylor - Subliminal Programming, Media Persuasion & Mind Control

Eldon Taylor - Mind Programming & How to Break Free from the Spell (Subscription)

Peter Russell - The Primacy of Consciousness

Peter Russell - Awareness, Presence & The Global Brain (Subscription)

Neil Kramer - Awakening, Eschatology & Entheogens

Neil Kramer - The Gates of Awakening & The Field Uplink

Steve Willner - Labyrinth of the Psychonaut

Michael Sharp - A Strong Theory of Consciousness and Creation

Michael Sharp - Consciousness & The Ascension Process

Share |

Latest News from our Front Page

Military Says No Presidential Authorization Needed To Quell “Civil Disturbances”
2013 05 17
A recent Department of Defense instruction alters the US code applying to the military’s involvement in domestic law enforcement by allowing US troops to quell “civil disturbances” domestically without any Presidential authorization, greasing the skids for a de facto military coup in America along with the wholesale abolition of Posse Comitatus. The instruction (embedded at the end of this article), which ...

Ancient Maya Pyramid Destroyed in Belize
2013 05 17
An archaeological group says it plans to take legal action. Despite its small size, the Caribbean country of Belize is known for a few outstanding characteristics: a spectacular barrier reef, a teeming rain forest, and extensive Maya ruins. It now has one fewer of those ruins. A construction company in Belize has been scooping stone out of the major pyramid at the site ...

Ginger: A Warming Herb
2013 05 17
Ginger is an Asian herb that is particularly well known to us in the West. Over time, and with trial and error, its stimulating properties and piquant flavor have been integrated into both our herbal “materia medica” and cuisine. Brewed as an herbal tea, ginger root is particularly helpful for those people who have underactive stomachs and difficulty producing adequate amounts ...

Australian man dead for 40 minutes revived with new CPR machine
2013 05 17
In an Australian first, doctors have used a new resuscitation technique to revive three patients who were clinically dead for up to an hour. One of the lucky survivors was Colin Fiedler, 49, who was pronounced dead at The Alfred Hospital in Melbourne, Victoria, after suffering a heart attack, The Herald Sun reported. Doctors brought Fieldler back to life using a U.S.-made ...

How a pregnancy test for humans caused a wave of global extinctions
2013 05 17
The deadly fungus Batrachochytrium dendrobatidis has been wiping out amphibian species across the globe for decades. But how did this global environmental disaster get started? A new study suggests that it came from doctors importing frogs for use in pregnancy tests. Since the 1980s, amphibian species have experienced a sharp decline in their numbers. Some estimates suggest that 400 or more ...

More News »