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 Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View
22.06.2018 | University of Sussex

nachricht New cellular pathway helps explain how inflammation leads to artery disease
22.06.2018 | Cedars-Sinai Medical Center

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>