Featured Research

from universities, journals, and other organizations

Brain researchers discover how retinal neurons claim best connections

Date:
October 31, 2013
Source:
Virginia Tech (Virginia Polytechnic Institute and State University)
Summary:
Scientists have discovered how retinal neurons claim prime real estate in the brain by controlling the abundance of a protein called aggrecan. The discovery could shed light on how to repair the injured brain.

Real estate agents emphasize location, location, and -- once more for good measure -- location. It's the same in a developing brain, where billions of neurons vie for premium property to make connections. Neurons that stake out early claims often land the best value, even if they don't develop the property until later.

Scientists at the Virginia Tech Carilion Research Institute and the University of Louisville have discovered that during neurodevelopment, neurons from the brain's cerebral cortex extend axons to the edge of the part of the brain dedicated to processing visual signals -- but then stop. Instead of immediately making connections, the cortical neurons wait for two weeks while neurons from the retina connect to the brain.

Now, in a study to be published in the Nov. 14 issue of the journal Cell Reports, the scientists have discovered how. The retinal neurons stop their cortical cousins from grabbing prime real estate by controlling the abundance of a protein called aggrecan.

Understanding how aggrecan controls the formation of brain circuits could help scientists understand how to repair the injured brain or spinal cord after injury or disease.

"Usually when neuroscientists talk about repairing injured brains, they're thinking about putting neurons, axons, and synapses back in the right place," said Michael Fox, an associate professor at the Virginia Tech Carilion Research Institute and lead author of the study. "It may be that the most important synapses -- the ones that drive excitation -- need to get there first. By stalling out the other neurons, they can get the best spots. This study shows that when we think about repairing damaged neural networks, we need to consider more than just where connections need to be made. We also need to think about the timing of reinnervation."

The researchers genetically removed the retinal neurons, which allowed the cortical axons to move into the brain earlier than they normally would.

"We were interested in what environmental molecular cues allow the retinal neurons to control the growth of cortical neurons," said Fox, who is also an associate professor of biological sciences in Virginia Tech's College of Science. "After years of screening potential mechanisms, we found aggrecan."

Aggrecan is a protein that has been well studied in cartilage, bones, and the spinal cord, where it is abundant after injuries. According to Fox, aggrecan may be able to isolate damaged areas of the spinal cord to stop inflammation and prevent further destruction. The downside, however, is that aggrecan inhibits axonal growth, which prevents further repair from taking place.

"Axons see this environment and either stop growing or turn around and grow in the opposite direction," said Fox.

Although it is less studied in the developing brain, aggrecan appears in abundance there. In the new study, the researchers found that retinal neurons control aggrecan in a region that receives ascending signals from retinal cells as well as descending signals from the cerebral cortex.

Once the retinal neurons have made connections, they cause the release of enzymes that break down the aggrecan, allowing cortical neurons to move in.

Fox said it is interesting that the retinal axons can grow in this region of the developing brain, despite the high levels of aggrecan. He suspects that it may be because retinal neurons express a receptor -- integrin -- that cortical axons do not express.


Story Source:

The above story is based on materials provided by Virginia Tech (Virginia Polytechnic Institute and State University). The original article was written by Ken Kingery. Note: Materials may be edited for content and length.


Journal Reference:

  1. JustinM. Brooks, Jianmin Su, Carl Levy, JessicaS. Wang, TaniaA. Seabrook, William Guido, MichaelA. Fox. A Molecular Mechanism Regulating the Timing of Corticogeniculate Innervation. Cell Reports, 2013; DOI: 10.1016/j.celrep.2013.09.041

Cite This Page:

Virginia Tech (Virginia Polytechnic Institute and State University). "Brain researchers discover how retinal neurons claim best connections." ScienceDaily. ScienceDaily, 31 October 2013. <www.sciencedaily.com/releases/2013/10/131031124608.htm>.
Virginia Tech (Virginia Polytechnic Institute and State University). (2013, October 31). Brain researchers discover how retinal neurons claim best connections. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2013/10/131031124608.htm
Virginia Tech (Virginia Polytechnic Institute and State University). "Brain researchers discover how retinal neurons claim best connections." ScienceDaily. www.sciencedaily.com/releases/2013/10/131031124608.htm (accessed October 2, 2014).

Share This



More Health & Medicine News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Pregnancy Spacing Could Have Big Impact On Autism Risks

Pregnancy Spacing Could Have Big Impact On Autism Risks

Newsy (Oct. 1, 2014) A new study says children born less than one year and more than five years after a sibling can have an increased risk for autism. Video provided by Newsy
Powered by NewsLook.com
Robotic Hair Restoration

Robotic Hair Restoration

Ivanhoe (Oct. 1, 2014) A new robotic procedure is changing the way we transplant hair. The ARTAS robot leaves no linear scarring and provides more natural results. Video provided by Ivanhoe
Powered by NewsLook.com
Insertable Cardiac Monitor

Insertable Cardiac Monitor

Ivanhoe (Oct. 1, 2014) A heart monitor the size of a paperclip that can save your life. The “Reveal Linq” allows a doctor to monitor patients with A-Fib on a continuous basis for up to 3 years! Video provided by Ivanhoe
Powered by NewsLook.com
Attacking Superbugs

Attacking Superbugs

Ivanhoe (Oct. 1, 2014) Two weapons hospitals can use to attack superbugs. Scientists in Ireland created a new gel resistant to superbugs, and a robot that can disinfect a room in minutes. Video provided by Ivanhoe
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:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

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