Featured Research

from universities, journals, and other organizations

Burst of neural activity marks transition between not seeing and seeing

Date:
January 18, 2010
Source:
Weizmann Institute of Science
Summary:
Scientists find a burst of neural activity at the transition between not seeing and seeing, revealing a clear threshold that must be crossed for perception to occur.

How do the visual images we experience, which have no tangible existence, arise out of physical processes in the brain? New research at the Weizmann Institute of Science provided evidence, for the first time, that an 'ignition' of intense neural activity underlies the experience of seeing.

In research recently published in the journal Neuron, Prof. Rafael Malach and research student Lior Fisch of the Weizmann Institute's Neurobiology Department worked with a neurosurgeon, Dr. Itzhak Fried of TelAvivSouraskyMedicalCenter, a distinguished team of medical doctors from the Center and Weizmann Institute students. They asked a group of epileptic patients who had had electrodes clinically implanted into their brains in preparation for surgery to volunteer for some perceptual awareness tasks. The subjects looked at a computer screen, which briefly presented a 'target' image -- a face, house, or man-made object.

This image was followed by a 'mask' -- a meaningless picture for distraction -- at different time intervals after the target image had been presented. This allowed the experimenter to control the visibility of the images -- the patients sometimes recognized the targets and sometimes failed to do so. By comparing the electrode recordings to the patients' reports of whether they had correctly recognized the image or not, the scientists were able to pinpoint when, where and what was happening in the brain as transitions in perceptual awareness took place.

Malach: 'We found that there was a rapid burst of neural activity occurring in the high-order visual centers of the brain -- centers that are sensitive to entire images of objects, such as faces -- whenever patients had correctly recognized the target image.' The scientists also found that the transition from not seeing to seeing happens abruptly. Fisch: 'When the mask was presented too soon after the target image, it 'killed' the visual input signals, resulting in the patients being unable to recognize the object. The patients suddenly became consciously aware of the target image at a clear threshold, suggesting that the brain needs a specific amount of time to process the input signals in order for conscious perceptual awareness to be 'ignited.''

This study is the first of its kind to uncover strong evidence linking 'ignition' of bursts of neural activity to perceptual awareness in humans. More questions remain: Is this the sole mechanism involved in the transition to perceptual awareness? To what extent is it a local phenomenon? By answering such questions, we might begin bridging the mysterious gap between mind and the brain.

Prof. Rafael Malach's research is supported by the Nella and Leon Benoziyo Center for Neurological Diseases; the Carl and Micaela Einhorn-Dominic Brain Research Institute; the S. and J. Lurje Memorial Foundation; the Benjamin and Seema Pulier Charitable Foundation, Inc; Vera Benedek, Israel; and Mary Helen Rowen, New York, NY. Prof. Malach is the incumbent of the Barbara and Morris Levinson Professorial Chair in Brain Research.


Story Source:

The above story is based on materials provided by Weizmann Institute of Science. Note: Materials may be edited for content and length.


Cite This Page:

Weizmann Institute of Science. "Burst of neural activity marks transition between not seeing and seeing." ScienceDaily. ScienceDaily, 18 January 2010. <www.sciencedaily.com/releases/2010/01/100114103130.htm>.
Weizmann Institute of Science. (2010, January 18). Burst of neural activity marks transition between not seeing and seeing. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2010/01/100114103130.htm
Weizmann Institute of Science. "Burst of neural activity marks transition between not seeing and seeing." ScienceDaily. www.sciencedaily.com/releases/2010/01/100114103130.htm (accessed April 18, 2014).

Share This



More Mind & Brain News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Study On Artists' Brain Shows They're 'Structurally Unique'

Study On Artists' Brain Shows They're 'Structurally Unique'

Newsy (Apr. 17, 2014) The brains of artists aren't really left-brain or right-brain, but rather have extra neural matter in visual and motor control areas. Video provided by Newsy
Powered by NewsLook.com
Is Apathy A Sign Of A Shrinking Brain?

Is Apathy A Sign Of A Shrinking Brain?

Newsy (Apr. 17, 2014) A recent study links apathetic feelings to a smaller brain. Researchers say the results indicate a need for apathy screening for at-risk seniors. Video provided by Newsy
Powered by NewsLook.com
Are School Dress Codes Too Strict?

Are School Dress Codes Too Strict?

AP (Apr. 16, 2014) Pushing the limits on style and self-expression is a rite of passage for teens and even younger kids. How far should schools go with their dress codes? The courts have sided with schools in an era when school safety is paramount. (April 16) Video provided by AP
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins