Featured Research

from universities, journals, and other organizations

Nerve cells in the eyes of flies and vertebrates use similar process to split up optical information

Date:
November 11, 2010
Source:
Max-Planck-Gesellschaft
Summary:
The eye is not just a lens that takes pictures and converts them into electrical signals. As with all vertebrates, nerve cells in the human eye separate an image into different image channels once it has been projected onto the retina. This pre-sorted information is then transmitted to the brain as parallel image sequences. Scientists have now discovered that fruit flies process optical information in a similar way. The evidence suggests that this type of wiring is an effective energy-saving mechanism and is therefore deployed by a diverse range of animal species.

Each individual eye in the fly's compound eye perceives "on" and "off" contrast changes. This information is split up right behind each individual eye (blue arrow). The L1 cells only transmit information about "on" edges ("light on"), the L2 cells only about "off" edges ("light off") to the output cells (green).
Credit: Max Planck Institute of Neurobiology / Schorner

The eye is not just a lens that takes pictures and converts them into electrical signals. As with all vertebrates, nerve cells in the human eye separate an image into different image channels once it has been projected onto the retina. This pre-sorted information is then transmitted to the brain as parallel image sequences.

Scientists from the Max Planck Institute of Neurobiology in Martinsried have now discovered that fruit flies process optical information in a similar way. The evidence suggests that this type of wiring is an effective energy-saving mechanism and is therefore deployed by a diverse range of animal species.

How does the mind perceive the world? This is not a trivial question: for many animal species, "seeing" is one of the most important senses. Every second, the eyes record a huge number of impressions which are converted by the photoreceptor cells into electrical signals. In vertebrates, image processing begins in the retina of the eye. Here, the nerve cells separate out the visual information in images featuring different content before transmitting them to the brain.

To understand something as complex as "seeing," scientists examine a somewhat simpler but extremely efficient system -- the fruit fly's brain. Despite their tiny size, fruit flies are ideal candidates for such research: they are masters of visual processing; the number of nerve cells involved is manageable, which means that each individual cell can be examined; and genetic tools make it possible to block individual cells and analyse their role in the system.

Scientists at the Max Planck Institute of Neurobiology have now discovered surprising parallels in the neuronal processing of fruit flies and vertebrates. The fly also transmits images directly from the sensory cells to various image channels. The information is then transmitted via a series of other cells to large, motion-sensitive nerve cells. These output cells of the motion vision system are responsible for visual flight control.

Scientists ascertained the early separation into different images by blocking certain cells using genetic engineering. They then exposed the flies to moving striped patterns in an LED arena and recorded the electrical responses of the large output cells. The various contrast changes, which occur as a result of the stripe movement, are perceived by the eye's photoreceptors. However, five nerve cells -- the lamina cells L1 to L5 -- are located directly behind every sensory cell. "We had been wondering for a long time why there are so many cells, which of them transmit information to the motion vision system, and what kind of information this is," reports Alexander Borst, who headed up the study. His team suppressed the activity of individual lamina cells while the flies watched the moving patterns. The experiments revealed that L1 and L2 cells are the main input channels into the flies' motion vision system. It got exciting as the team discovered that the cells transmit only certain partial information: L1 only responds if a dark/bright edge passes by (light on), while L2 only transmits information about a moving bright/dark edge (light off). This represents a clear parallel with the eyes of vertebrates, where ON and OFF bipolar cells, as they are known, also respond only to specific contrast changes.

"It can be no coincidence that we find this separation of contrast information in all vertebrates and now also in flies," surmises Alexander Borst. The neurobiologist already has a theory as to why this wiring has been maintained so consistently throughout evolution: it allows the brain to save energy. If only one cell relayed the information about the various contrast changes, it would have to maintain a basic membrane voltage, which would intensify in a "light on" situation and weaken in a "light off" situation. Such a basic membrane voltage requires energy. Having two cells is therefore more efficient, as only one needs to be active when "its" contrast change occurs.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. Maximilian Jφsch, Bettina Schnell, Shamprasad Varija Raghu, Dierk F. Reiff & Alexander Borst. ON- and OFF-pathways in Drosophila motion vision. Nature, November 11, 2010 DOI: 10.1038/nature09545

Cite This Page:

Max-Planck-Gesellschaft. "Nerve cells in the eyes of flies and vertebrates use similar process to split up optical information." ScienceDaily. ScienceDaily, 11 November 2010. <www.sciencedaily.com/releases/2010/11/101110131158.htm>.
Max-Planck-Gesellschaft. (2010, November 11). Nerve cells in the eyes of flies and vertebrates use similar process to split up optical information. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2010/11/101110131158.htm
Max-Planck-Gesellschaft. "Nerve cells in the eyes of flies and vertebrates use similar process to split up optical information." ScienceDaily. www.sciencedaily.com/releases/2010/11/101110131158.htm (accessed April 23, 2014).

Share This



More Plants & Animals News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Monkeys Are Better At Math Than We Thought, Study Shows

Monkeys Are Better At Math Than We Thought, Study Shows

Newsy (Apr. 23, 2014) — A Harvard University study suggests monkeys can use symbols to perform basic math calculations. Video provided by Newsy
Powered by NewsLook.com
Raw: Leopard Bites Man in India

Raw: Leopard Bites Man in India

AP (Apr. 22, 2014) — A leopard caused panic in the city of Chandrapur on Monday when it sprung from the roof of a house and charged at rescue workers. (April 22) Video provided by AP
Powered by NewsLook.com
Iowa College Finds Beauty in Bulldogs

Iowa College Finds Beauty in Bulldogs

AP (Apr. 22, 2014) — Drake University hosts 35th annual Beautiful Bulldog Contest. (April 21) Video provided by AP
Powered by NewsLook.com
805-Pound Shark Caught Off The Coast Of Florida

805-Pound Shark Caught Off The Coast Of Florida

Newsy (Apr. 22, 2014) — One Florida fisherman caught a 805-pound shark off the coast of Florida earlier this month. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins