Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why Sensory Perception Changes When the Brain Rests

06.02.2009
New research by Weizmann Institute scientists and their colleagues helps explain why we don’t experience sights or sounds when there is no input to our sensory organs – even though our sense centers are functioning.

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 screensaver. 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.

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; Ms. Vera Benedek, Israel; Benjamin and Seema Pulier Charitable Foundation, Inc.; and Ms. Mary Helen Rowen, New York, NY. Prof. Malach is the incumbent of the Barbara and Morris Levinson Professorial Chair in Brain Research.

The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,600 scientists, students, technicians, and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials, and developing new strategies for protecting the environment.

Jennifer Manning | Newswise Science News
Further information:
http://www.acwis.org

More articles from Life Sciences:

nachricht 'Lipid asymmetry' plays key role in activating immune cells
20.02.2018 | Biophysical Society

nachricht New printing technique uses cells and molecules to recreate biological structures
20.02.2018 | Queen Mary University of London

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>