Study with totally blind people shows how light helps activate the brain

October 28, 2013
Brain

Light enhances brain activity during a cognitive task even in some people who are totally blind, according to a study conducted by researchers at the University of Montreal and Boston's Brigham and Women's Hospital. The findings contribute to scientists' understanding of everyone's brains, as they also revealed how quickly light impacts on cognition.

"We were stunned to discover that the still respond significantly to in these rare three completely blind patients despite having absolutely no conscious vision at all," said senior co-author Steven Lockley. "Light doesn't just allow us to see, it tells the brain whether it's night or day which in—turn ensures that our physiology, metabolism and behavior are synchronized with environmental time". "For diurnal species like ours, light stimulates day-like , improving alertness and mood, and enhancing performance on many cognitive tasks," explained senior co-author Julie Carrier. The results indicate that their brains can still "see", or detect, light via a novel photoreceptor in the ganglion cell layer of the retina, different from the rods and cones we use to see.

Scientists believe, however, that these specialized photoreceptors in the retina also contribute to visual function in the brain even when cells in the retina responsible for normal image formation have lost their ability to receive or process light. A previous study in a single blind patient suggested that this was possible but the research team wanted to confirm this result in different patients. To test this hypothesis, the three participants were asked to say whether a was on or off, even though they could not see the light. "We found that the participants did indeed have a non-conscious awareness of the light—they were able to determine correctly when the light was on greater than chance without being able to see it," explained first author Gilles Vandewalle.

The next steps involved looking closely at what happened to brain activation when light was flashed at their eyes at the same time as their attentiveness to a sound was monitored. "The objective of this second test was to determine whether the light affected the brain patterns associated with attentiveness—and it did," said first author Olivier Collignon.

Finally, the participants underwent a functional MRI brain scan as they performed a simple sound matching task while lights were flashed in their eyes. "The fMRI further showed that during an auditory working memory task, less than a minute of blue light activated brain regions important to perform the task. These regions are involved in alertness and cognition regulation as well being as key areas of the default mode network," Vandewalle explained. Researchers believe that the default network is linked to keeping a minimal amount of resources available for monitoring the environment when we are not actively doing something. "If our understanding of the is correct, our results raise the intriguing possibility that light is key to maintaining sustained attention" agreed Lockley and Carrier. "This theory may explain why the brain's performance is improved when light is present during tasks."

Explore further: Vision trumps hearing in study

More information: Vandewalle G, Collignon O, Hull JT, Daneault V, Albouy G, Lepore F, Phillips C, Doyon J, Czeisler CA, Dumont M, Lockley SW, Carrier J. Blue Light Stimulates Cognitive Brain Activity in Visually Blind Individuals. J Cogn Neurosci. 2013 Jul 16. [Epub ahead of print]

Related Stories

Vision trumps hearing in study

September 11, 2013
A Duke University study used puppet-based comedy to demonstrate the complicated inner-workings of the brain and shows what every ventriloquist knows: The eye is more convincing than the ear.

Getting an expected award music to the brain's ears

September 25, 2013
Several studies have shown that expecting a reward or punishment can affect brain activity in areas responsible for processing different senses, including sight or touch. For example, research shows that these brain regions ...

What color is your night light? It may affect your mood

August 6, 2013
When it comes to some of the health hazards of light at night, a new study suggests that the color of the light can make a big difference.

Brain imaging study reveals the wandering mind behind insomnia

August 30, 2013
A new brain imaging study may help explain why people with insomnia often complain that they struggle to concentrate during the day even when objective evidence of a cognitive problem is lacking.

Switching night vision on or off

March 27, 2013
Neurobiologists at the Friedrich Miescher Institute have been able to dissect a mechanism in the retina that facilitates our ability to see both in the dark and in the light. They identified a cellular switch that activates ...

Wireless subretinal prostheses allows blind mice to see light

June 19, 2013
(Medical Xpress)—A team of researchers from the U.S. and Scotland has developed a new type of retinal prostheses designed to restore sight to blind patients. In their paper published in the journal Nature Communications, ...

Recommended for you

Scientists capture first image of major brain receptor in action

July 24, 2017
Columbia University Medical Center (CUMC) researchers have captured the first three-dimensional snapshots of the AMPA-subtype glutamate receptor in action. The receptor, which regulates most electrical signaling in the brain, ...

Research identifies new brain death pathway in Alzheimer's disease

July 24, 2017
Alzheimer's disease tragically ravages the brains, memories and ultimately, personalities of its victims. Now affecting 5 million Americans, Alzheimer's disease is the sixth leading cause of death in the U.S., and a cure ...

Illuminating neural pathways in the living brain

July 24, 2017
Using light alone, scientists from the Max Planck Institute of Neurobiology in Martinsried are now able to reveal pairs or chains of functionally connected neurons under the microscope. The new optogenetic method, named Optobow, ...

Study suggests link between autism, pain sensitivity

July 24, 2017
New research by a UT Dallas neuroscientist has established a link between autism spectrum disorder (ASD) and pain sensitivity. 

Eye test could help diagnose autism

July 24, 2017
A new study out in European Journal of Neuroscience could herald a new tool that helps physicians identify a sub-group of people with Autism spectrum disorders (ASD). The test, which consists of measuring rapid eye movements, ...

The neural codes for body movements

July 21, 2017
A small patch of neurons in the brain can encode the movements of many body parts, according to researchers in the laboratory of Caltech's Richard Andersen, James G. Boswell Professor of Neuroscience, Tianqiao and Chrissy ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.