Navigation Links
Behind closed eyes
Date:2/4/2009

Even when our eyes are closed, the visual centers in our brain are humming with activity. Weizmann Institute scientists and others have shown in the last few years that the magnitude of sense-related activity in a brain that's disengaged from seeing, touching, etc., is quite similar to that of one exposed to a stimulus. New research at the Institute has now revealed details of that activity, explaining why, even though our sense centers are working, we don't experience sights or sounds when there's nothing coming in through our sensory organs.

The previous studies of Prof. Rafael Malach and research student Yuval Nir of the Neurobiology Department used functional magnetic resonance imaging (fMRI) to measure brain activity in active and resting states. But fMRI is an indirect measurement of brain activity; it can't catch the nuances of the pulses of electricity that characterize neuron activity.

Together with Prof. Itzhak Fried of the University of California at Los Angeles and a team at the EEG unit of the Tel Aviv Sourasky Medical Center, the researchers found a unique source of direct measurement of electrical activity in the brain: data collected from epilepsy patients who underwent extensive testing, including measurement of neuronal pulses in various parts of their brain, in the course of diagnosis and treatment.

An analysis of this data showed conclusively that electrical activity does, indeed, take place even in the absence of stimuli. But the nature of the electrical activity differs if a person is experiencing a sensory event or undergoing its absence. In results that appeared recently in Nature Neuroscience, the scientists showed that during rest, brain activity consists of extremely slow fluctuations, as opposed to the short, quick bursts that typify a response associated with a sensory percept. This difference appears to be the reason we don't experience hallucinations or hear voices that aren't there during rest. The resting oscillations appear to be strongest when we sense nothing at all during dream-free sleep.

The slow fluctuation pattern can be compared to a computer screen-saver. Though its function is still unclear, the researchers have a number of hypotheses. One possibility is that neurons, like certain philosophers, must 'think' in order to be. Survival, therefore, is dependant on a constant state of activity. Another suggestion is that the minimal level of activity enables a quick start when a stimulus eventually presents itself, something like a getaway car with the engine running. Nir: 'In the old approach, the senses are 'turned on' by the switch of an outside stimulus. This is giving way to a new paradigm in which the brain is constantly active, and stimuli change and shape that activity.'

Malach: 'The use of clinical data enabled us to solve a riddle of basic science in a way that would have been impossible with conventional methods. These findings could, in the future, become the basis of advanced diagnostic techniques.' Such techniques might not necessarily require the cooperation of the patient, allowing them to be used, for instance on people in a coma or on young children.


'/>"/>

Contact: Yivsam Azgad
news@weizmann.ac.il
972-893-43856
Weizmann Institute of Science
Source:Eurekalert

Related biology news :

1. Scientists decipher mechanism behind antimicrobial hole punchers
2. New study uncovers secrets behind butterfly wing patterns
3. Mystery behind the strongest creature in the world
4. Pitt and University of Chicago researchers uncover process behind heart muscle contraction
5. Incense is psychoactive: Scientists identify the biology behind the ceremony
6. The secret behind silkworms hardy stomachs
7. Forum to focus on math and mechanics behind life processes
8. Source of drug-tolerant tuberculosis possibly behind TB relapses, intensity of treatment
9. Birds migrate earlier, but some may be left behind as the climate warms rapidly
10. UCLA study identifies mechanism behind mind-body connection
11. UCSF researchers identify virus behind mysterious parrot disease
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/2/2016)... The Department of Transport Management (DOTM) ... million US Dollar project, for the , Supply ... Enrolment, and IT Infrastructure , to ... implementation of Identity Management Solutions. Numerous renowned international vendors participated ... was selected for the most compliant and innovative ...
(Date:6/1/2016)... 1, 2016 Favorable Government Initiatives ... and Criminal Identification to Boost Global Biometrics System Market ... TechSci Research report, " Global Biometrics Market By ... and Opportunities, 2011 - 2021", the global biometrics market ... on account of growing security concerns across various end ...
(Date:5/16/2016)... 2016   EyeLock LLC , a market leader ... of an IoT Center of Excellence in ... development of embedded iris biometric applications. EyeLock,s ... and security with unmatched biometric accuracy, making it the ... DNA. EyeLock,s platform uses video technology to deliver a ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... PHILADELPHIA , June 27, 2016  Liquid ... today announced the funding of a Sponsored Research ... study circulating tumor cells (CTCs) from cancer patients.  ... changes in CTC levels correlate with clinical outcomes ... therapies. These data will then be employed to ...
(Date:6/24/2016)... ... 24, 2016 , ... While the majority of commercial spectrophotometers and fluorometers use ... 6000i models are higher end machines that use the more unconventional z-dimension of 20mm. ... from the bottom of the cuvette holder. , FireflySci has developed several Agilent ...
(Date:6/23/2016)... CAMBRIDGE, Mass. , June 23, 2016 /PRNewswire/ ... the development of novel compounds designed to target ... compound, napabucasin, has been granted Orphan Drug Designation ... in the treatment of gastric cancer, including gastroesophageal ... cancer stemness inhibitor designed to inhibit cancer stemness ...
(Date:6/23/2016)... ... 23, 2016 , ... Charm Sciences, Inc. is pleased to ... AOAC Research Institute approval 061601. , “This is another AOAC-RI approval of the ... Vice President of Regulatory and Industrial Affairs. “The Peel Plate methods perform comparably ...
Breaking Biology Technology: