Major discovery explains how adult brain cleans out dead brain cells, produces new ones

August 10, 2011

(Medical Xpress) -- Adult brains generate thousands of new brain cells called neurons each day; however only a small fraction of them survive. The rest die and are consumed by scavenger cells called phagocytes. Until now, scientists have not fully understood how this process works, which phagocytes are unique in the brain, and how the removal of dead neurons influences the production of new neurons.

In humans, neurogenesis, or the formation of new , largely ceases in most areas of the during adulthood. However, in two there is strong evidence that substantial numbers of new neurons are naturally generated (in the hippocampus, which is involved in memory forming, organizing and storing, and the , involved in the perception of odors).

UVA Health System researchers have made a pivotal discovery in understanding this complicated process, and their findings could one day help scientists devise novel therapies to promote neurogenesis in the adult brain and re-establish its function in patients suffering from depression, post-traumatic stress disorder, and other mental disorders, in which adult neurogenesis is impaired .

The findings appear in a study published online July 31, 2011 in the journal and led by two UVA researchers -- Jonathan Kipnis, PhD, associate professor of neuroscience, and Kodi S. Ravichandran, PhD, chair of the UVA Department of Microbiology and director of the UVA Center for Cell Clearance. Zhenjie Lu, PhD, is the first author on this work and was instrumental in combining the methodologies in the Kipnis lab (which focuses on basic mechanisms underlying neurological disorders) and the Ravichandran lab (which focuses on cell clearance) to address adult neurogenesis through a combination of in vivo studies in normal and genetically altered mice, and ex vivo studies using neuronal cultures.

Through their research, UVA scientists discovered that certain types of , called the doublecortin (DCX)-positive neuronal progenitors (or “newborn neurons”), serve a dual role in the regulation of production and elimination of new . Progenitor cells generally act as a repair system for the body, replenishing special cells and maintaining blood, skin and intestinal tissues.  This new discovery points to the ability of these cells to clean each other out, which ultimately benefits the regeneration process.

“Our study provides the first evidence that DCX+ cells, in addition to serving their function as neuronal precursors in the brain, also function as [scavenger cells] by clearing out their dead brethren -- and that this process is required to maintain continuous generation of new neurons in the brain,” says Kipnis.

“These findings raise the possibility that this newly discovered process could be manipulated to rejuvenate the brain by regulating the addition of new neurons,” says Ravichandran.

This discovery, Kipnis adds, also could shed new light on our understanding of how the process of adult neurogenesis is regulated in the healthy brain, and in turn provide insights on diseased brains, where adult is severely impaired.

“The birth and death of new neurons in the adult brain have been implicated in ongoing learning and memory,” says Kevin Lee, PhD, chair of the Department of Neuroscience and professor of neurological surgery. “The findings by Kipnis, Ravichandran, Lu and associates are fascinating, because they describe a novel process regulating the production and removal of adult-born neurons. This represents an important step toward identifying mechanisms that might be manipulated to control the number of new neurons in the . Regulating new adult neurons in this manner could open a novel avenue for modifying basic cognitive functions, including learning.”

More information: Research paper: www.nature.com/ncb/journal/vao … nt/full/ncb2299.html

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8 comments

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hush1
not rated yet Aug 10, 2011
This article:
http://medicalxpr...une.html
calls this 'pruning'.

This article:
http://medicalxpr...ain.html
can benefit from the posted link and posted article.

This poster believes collaboration among the thousands near identical research will shorten the time between discovery, progress, clinical trails, and application.

This poster is a dreamer.
Eric_B
5 / 5 (3) Aug 10, 2011
tragically funny, hush...

too bad america isn't interested in dramatically increasing research and aggressively encouraging collaboration as new technologies emerge.

our imaginations have yet to grasp the possibilities and ways that new nano and bio tech discoveries across this country and the globe could be combined in novel ways if there was a way to bring the progenitors together...
knowledge_treehouse
not rated yet Aug 10, 2011
I bet its normally the ones that don't get used that die.

improving a person's global (general) cognitive fitness with specific (local) enrichment factors: http://episin.blo...ith.html
knowledge_treehouse
5 / 5 (1) Aug 10, 2011
What are the relative rates of neurogenesis in different parts of the brain?
hush1
not rated yet Aug 10, 2011
Very good question.
The very poor answer:
Unable to find research on this.
Techno1
1 / 5 (1) Aug 10, 2011
tragically funny, hush...


It's all about Capitalism and patent laws.

whoever owns the rights to any new drug or technology OWNS everyone else.

Therefore, they have no motivation to work together with other groups, since whoever gets a working product out of any given technology or research first immediately "owns" that technology...forever...and when they die, their descendents or their company "owns" the technology...forever...

This exploitation drives everything in our civilization, and yet it is a direct violation of the founding principles of this nation, particularly as it regards medical technology, whereby Jefferson writes that we have a inalienable RIGHT to life...endowed by the creator.

The patent system perpetuates "competition," because Capitalism perpetuates serfdom, and whoever owns the patent gets to be a "lord". But the competition only works before the patent is issued, not afterwards. After is monopoly.
Techno1
1 / 5 (1) Aug 10, 2011
too bad america isn't interested in dramatically increasing research and aggressively encouraging collaboration as new technologies emerge.


Of course not.

if you're an oil or coal company, you don't want cheap energy. you don't even want to supply cheap energy, even if your company is the one to do it. That's useless to the Capitalist, as his job, being a capitalist, is to rob everyone else as severely as possible, yet as legally as possible.

The oil company doesn't want cheap energy. They don't want cold fusion, nor even hot fusion, not even if they would be the one to provide it...They can't make money off "cheap" energy. They need an excuse to raise the prices more and more, and would do so ASAP if allowed to do so.

Many medial companies and even hospitals are the same way. They charge you $5000 dollars for a visit to the emergency room, and don't even diagnose you with anything, and don't even prove what was wrong with you, beyond symptoms you already knew...
Techno1
1 / 5 (1) Aug 10, 2011
our imaginations have yet to grasp the possibilities and ways that new nano and bio tech discoveries across this country and the globe could be combined in novel ways if there was a way to bring the progenitors together


I see scant little evidence that the majority of politicians, nor americans in general, would know what nanotechnology is.

Besides Star Trek, it's never mentioned anywhere in pop-culture, and it's only mentioned from time to time on something like Discovery Channel or one of the few other "learning" channels.

AT one time, TLC was all about astronomy and technology, and then they became a "reality tv show" channel, which rewards dog trainers and 16 year old moms, because the American populace is too stupid and disinterested in the possibilities for them to make any money...and money is everything, because this is capitalism...so end intelligent programming, insert mindless drivel here, but we're still "The Learning Channel".

Booo...

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