Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

An 'eye catching' vision discovery

28.07.2009
Nearly all species have some ability to detect light. At least three types of cells in the retina allow us to see images or distinguish between night and day. Now, researchers at the Johns Hopkins School of Medicine have discovered in fish yet another type of cell that can sense light and contribute to vision.

Reporting in this week's Nature, the team of neuroscientists shows that retinal horizontal cells, which are nerve cells once thought only to talk to neighboring nerve cells and not even to the brain, are light sensitive themselves.

"This is mind-boggling," says King-Wai Yau, Ph.D., a professor of neuroscience at the Solomon H. Snyder Department of Neuroscience at Johns Hopkins.

"For more than 100 years, it's been known that rod cells and cone cells are responsible for sensing light, and therefore, vision," says Yau. "Then, about seven years ago, another light sensor was discovered in the retina, revealing a third type of light-sensitive cells in mammals, so we set out to look at whether this was true in other vertebrates as well."

Focusing their efforts on the melanopsin light sensor, which is responsible for sensing day and night but barely involved — in mammals, at least — in seeing images, Yau's team looked for melanopsin-containing cells in other vertebrates, and found some in the retinal horizontal cells in goldfish and catfish.

Catfish contain two flavors of retinal horizontal cells: those that connect to cone cells, which respond to bright light, and those that connect to rod cells, which respond to dim light. The team took electrical readings from single isolated retinal horizontal cells. They found that light caused a change in electrical current in cone horizontal cells but not in rod horizontal cells.

Horizontal cells, says Yau, allow cross-talk between neighboring photoreceptor cells, allowing these cells to compare the light they sense, a process necessary for the brain to see images. "The brain processes what it sees in context to the surroundings," says Yau. "This allows our brain to see borders and contours—horizontal cells are the reason why we can recognize and see a face, for example."

Testing light at different wavelengths, the team found that these fish horizontal cells are thousands of times less light sensitive than their partner cone cells.

"The bottom line is that the light effect on the horizontal cells is subtle, perhaps to allow the eyes of these animals to fine-tune their functions to different ambient light conditions," says Yau. "But that these horizontal cells are light sensitive at all is a very surprising finding and changes how we think about retinas as a whole."

Learning more about how the light sensitivity of horizontal cells contributes to image vision will require studying whole retinas, not just single cells. Yau, whose goal is to understand vision, is hooked. "Maybe," he says, "there are still other photosensitive cells in the eye that we don't know about yet."

This study was funded by the National Institutes of Health and the António Champalimaud Vision Award.

Authors on the paper are Ning Cheng, Takashi Tsunenari and Yau, all of Johns Hopkins.

The Solomon H. Snyder Department of Neuroscience at Johns Hopkins:
http://neuroscience.jhu.edu/
King-Wai Yau:
http://neuroscience.jhu.edu/KingWaiYau.php

Audrey Huang | EurekAlert!
Further information:
http://www.jhmi.edu
http://www.nature.com/nature/index.html

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>