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 Stiffness matters
22.02.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Separate brain systems cooperate during learning, study finds
22.02.2018 | Brown University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

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...

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

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>