Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UCSD Biologists Discover Chemical Important In Guiding Visual System Development

28.10.2004


University of California, San Diego neurobiologists have discovered a chemical responsible for the bursts of electrical activity in the brain that guide the development of the visual system, a finding that may bring rewiring of damaged visual circuits closer to reality.



The scientists, who presented their evidence at a session of the annual Society for Neuroscience meeting in San Diego, said their discovery could also lead to a better understanding of birth defects in children born to mothers taking epilepsy medication.

Scientists have long recognized that spontaneous neural activity is needed for the normal development of the visual circuits in the brain, but how this activity is created is not well understood. UCSD researchers Marla Feller and Chih-Tien Wang detailed at the meeting their evidence that the chemical messenger adenosine controls the timing of these bursts of electrical activity. Knowing what triggers these waves of activity could make it possible to recreate them for therapeutic purposes, they said, and may shed light on disorders caused by their disruption.


“The waves of neural activity in the developing visual system have a remarkably stereotyped temporal pattern,” said Feller, an assistant professor of biology who led the study. “We show that the neurotransmitter adenosine may control this pattern by altering the excitability of cells in the retina. Ultimately findings that help us understand the mechanism that generates this spontaneous activity might make it possible to recreate it later in life; for example, to coax regenerated nerve cells to reconnect appropriately after an injury.” “Another possible application of inducing patterned retinal activity in adult circuits is to set up the wiring in people who have been blinded since birth but then have some sort of surgery—like cataract removals—that gives them sight for the first time,” added Feller.

The researchers speculated that adenosine’s role in controlling spontaneous neural activity may also explain why mothers taking medication for epilepsy are twice as likely to have children with a set of birth defects known as “fetal anti-convulsant syndrome.” The spontaneous waves of activity occur in the developing visual system of the fetus during the second trimester of pregnancy. Therefore, medications taken by the mother that influence adenosine levels in the brain of the fetus could disrupt the spontaneous activity patterns.

“Understanding adenosine’s role in modulating activity in the developing retina may explain some of the developmental defects seen in fetal-anticonvulsant syndrome,” said Wang, a postdoctoral fellow. “Drugs taken during pregnancy to control epilepsy may have effects similar to adenosine in the developing fetus. The visual problems and other developmental defects characteristic of fetal anti-convulsant syndrome could result from these drugs interfering with the spontaneous activity necessary for patterning the developing nervous system.”

A previous study by Feller and her colleagues showed that the pattern of neural activity is essential for the retinal ganglion cells—which extend projections from the retina to the brain—to form the correct connections in the brain. In mutant mice where the retinal ganglion cells fired randomly, rather than in well-coordinated waves that propagate across the retina from one cell to neighboring cells, these projections were never refined and remained as they were early in development.

To find the factor that might be responsible for coordinating the behavior of the retinal ganglion cells, Feller and Wang took electrical recordings from retinal ganglion cells kept alive in a dish. Following up on work started when Feller was a postdoctoral fellow working with Carla Shatz, a professor of neurobiology at Harvard Medical School, Feller and Wang found that drugs to enhance adenosine’s action increased the frequency of the waves of electrical activity in the cells, and decreasing adenosine’s action decreased their frequency. The electrical recordings showed that adenosine was acting directly on the retinal ganglion cells to alter how easily they could be excited.

These results provide new insight into the mechanism by which the spontaneous electrical activity essential for patterning the developing nervous system is generated, but Feller cautions that they are still preliminary. “Research into the role of spontaneous neural activity in development has progressed a great deal since the days when it was generally accepted that the genes specified everything except the final fine tuning of connections,” says Feller. “This study sheds light on the important question of how spontaneous activity is generated, but we still have much to learn about the details of the cellular processes involved.”

The study was supported by the McKnight Foundation and the National Eye Institute of the National Institutes of Health.

Sherry Seethaler | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht Scientists unlock ability to generate new sensory hair cells
22.02.2017 | Brigham and Women's Hospital

nachricht New insights into the information processing of motor neurons
22.02.2017 | Max Planck Florida Institute for Neuroscience

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>