Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

After a time-shift, mixed signals from the circadian clock

24.05.2005


Circadian rhythms in mammalian behavior, physiology, and biochemistry are controlled by the central clock within a brain structure known as the suprachiasmatic nucleus (SCN). The clock is synchronized to environmental cycles of light and dark. It is well known, from everyday experience, that adjusting to new light schedules takes several days, though the details of how this adaptation takes place are not well understood.



Researchers now report findings that suggest this adaptation process does not necessarily involve a gradual and synchronous adaptation by the neurons that comprise the central circadian clock--rather, that different components of the clock tend to adapt to a shifted light schedule at two different speeds.

The work is reported in the May 24 issue of Current Biology by a research team led by Johanna H. Meijer of Leiden University Medical Center in The Netherlands.


The researchers studied clock-resetting behavior in rats that were exposed to a six-hour delay of the light schedule, a shift that mimics a transition from the eastern U.S. to western Europe. By performing electrophysiological analysis of cells that constitute the central circadian clock, the researchers made a surprising discovery: one part of the clock mechanism, represented by a dorsal (upper) group of cells, exhibited oscillations in activity that corresponded to slow resetting of the clock in response to the shifted light schedule, while another part of the clock, represented by a ventral (lower) group of cells, exhibited a distinct pattern of activity that corresponded to fast resetting of the clock.

Perhaps contributing to the different behavior of the two groups of clock cells are the effects on these cells of the neurotransmitter GABA, which the researchers found to excite the cells of the dorsal SCN while inhibiting neurons in the ventral SCN. Because GABA transmits information between the ventral and dorsal SCN, such differences in effect might influence, in complex ways, how the two groups of cells adapt to a shifted light schedule.

The authors conclude that the phases of activity in the ventral and dorsal clock shift with different speeds. During a schedule shift corresponding to a transition from the U.S. to western Europe, the ventral part of the clock is immediately synchronized to the new light schedule, but the dorsal part of the clock requires several days to adjust. This results temporarily in bimodal patterns of electrical activity that are generated by the clock within the SCN. Because electrical activity is the output of the circadian clock, the findings suggest that after a significant shift in light schedule, the rest of the brain is transiently--for a duration of about six days--exposed to complex signaling patterns from the circadian clock.

Heidi Hardman | EurekAlert!
Further information:
http://www.current-biology.com
http://www.cell.com

More articles from Life Sciences:

nachricht Researchers reveal new details on aged brain, Alzheimer's and dementia
21.11.2017 | Allen Institute

nachricht Nanoparticles help with malaria diagnosis – new rapid test in development
21.11.2017 | Fraunhofer-Institut für Silicatforschung ISC

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

From Hannover around the world and to the Mars: LZH delivers laser for ExoMars 2020

21.11.2017 | Physics and Astronomy

Borophene shines alone as 2-D plasmonic material

21.11.2017 | Materials Sciences

Penn study identifies new malaria parasites in wild bonobos

21.11.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>