Navigation Links
Life and death in the hippocampus: what young neurons need to survive

Whether newborn nerve cells in adult brains live or die depends on whether they can muscle their way into networks occupied by mature neurons. Neuroscientists at the Salk Institute for Biological Studies pin-pointed the molecular survival gear required for a young neuron to successfully jump into the fray and hook up with other cells.

In a study published in a forthcoming issue of Nature, researchers in the lab of Fred H. Gage, Ph.D., a professor in the Gene Expression Laboratory and the Vi and John Adler Chair for Research on Age-Related Neurodegenerative Diseases, identify a subunit of the NMDA receptor, a protein complex that transduces signals sent by neighboring cells, as the cells' life-saving equipment that allows them to integrate into the existing brain circuitry.

The NMDA receptor is activated by the neurotransmitter glutamate, a chemical released by neurons in order to transmit information to neighboring cells. Whenever the receptor picks up a glutamate signal it is stimulated and relays the signal. But for newborn neurons that signal means something else entirely -- survival.

"When we removed the NMDA receptor, that is when cells make connections in response to glutamate in the environment, the newborn neurons withered and died at a specific stage of their maturation," explains Gage. " The NMDA receptor modulates synapse formation and determines what pattern of input activity new neurons receive, which in turn determines survival or death."

Combining mouse genetics and gene transfer techniques, Gage and a team headed by former postdoctoral fellow Ayumu Tashiro, Ph.D., injected a virus carrying a pair of molecular shears capable of deleting a gene encoding part of the NMDA receptor into the hippocampus, a brain region harboring neural stem cells that give rise to new neurons. Newly born neurons infected with virus were marked by a fluorescent dye enabling detection of neurons derived from those cells.

A few we eks later, animals that received the virus showed fewer fluorescent neurons compared to mice injected with a benign virus lacking the shears, meaning fewer new neurons had survived originating from neural stem cells in which the NMDA receptor had been eliminated.

Listening to Gage, one gets the impression that the hippocampus is a dangerous place for a fledgling neuron trying to elbow its way into pre-existing networks. "It's rough in there!" he concedes. "The NMDA receptor-mediated event is a competition between mature cells vying for connectivity and young guys competing with both the mature cells and their peers to fit in. You are selecting for the cell that performs best in this environment."

The Gage lab previously showed that the rate at which new neurons emerge from stem cells depends on an animal's activity. "If you put animals in an enriched environment and give them access to running wheels, you increase survival of new brain cells," says Gage. "Now we show that stimulation may, in part, be mediated through the NMDA receptor."

Those studies had also shown that young and middle-aged "exercised" rats perform better on learning tasks such as maze swimming, indicating that new neurons are more than just a backup supply but actually enhance learning.

"Remarkably, new neurons are born in the hippocampus, a structure whose function is to acquire new information," says Gage. "That suggests that new cells are involved in how we learn."

This ongoing struggle for connections between young and mature neurons is apparently more than just a spectacle designed to keep Mother Nature amused: the fact that enhanced learning is correlated with adult neurogenesis suggests constant rearrangements within neural networks are absolutely necessary for learning to occur.

In fact, data emerging from studies in the Gage lab reinforces the commonly held belief that using one's brain cells is the best way to optimize brain funct ion throughout one's lifetime.

"In the natural course of aging there is cognitive decline," says Gage. "We know we lose the ability to generate new neurons with age. We are currently trying to figure out how to generate as many neurons as possible to potentially enhance learning or increase the amount of neurogenesis in adults."


'"/>

Source:Salk Institute


Related biology news :

1. Combination therapy boosts effectiveness of telomere-directed cancer cell death
2. Enzyme allows B cells to resist death, leading to leukemia
3. Critical role in programmed cell death identified
4. A comprehensive response to HIV could prevent 10 million AIDS deaths in Africa by 2020
5. The death of a very special chimpanzee
6. The very unexpected life and death of a leukemic cell
7. Solutions that reduce death of marine life reeled in by International Smart Gear Competition
8. Emergence of cancer as major cause of childhood death in developing countries is not being adequately addressed
9. Hanging baskets of sex and death help fruit growers
10. UT Southwestern researchers discover master switch in cell death
11. Prescription pain patch abuse blamed for increase in deaths
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:6/22/2016)... -- The American College of Medical Genetics and Genomics was once ... one of the fastest-growing trade shows during the Fastest 50 ... Las Vegas . Winners ... each of the following categories: net square feet of paid ... The 2015 ACMG Annual Meeting was ranked 23 out of ...
(Date:6/22/2016)... -- On Monday, the Department of Homeland Security (DHS) ... for the Biometric Exit Program. The Request for Information ... explains that CBP intends to add biometrics to confirm ... States , in order to deter visa overstays, ... Logo - http://photos.prnewswire.com/prnh/20160622/382209LOGO ...
(Date:6/20/2016)... June 20, 2016 Securus Technologies, a ... solutions for public safety, investigation, corrections and monitoring ... involved, it has secured the final acceptance by ... for Managed Access Systems (MAS) installed. Furthermore, Securus ... to be installed by October, 2016. MAS distinguishes ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... HOUSTON , June 23, 2016 ... agreement with the Cy-Fair Sports Association to serve ... of the agreement, Houston Methodist Willowbrook will provide ... education and connectivity with association coaches, volunteers, athletes ... partner with the Cy-Fair Sports Association and to ...
(Date:6/23/2016)... ... June 23, 2016 , ... Supplyframe, ... of the Supplyframe Design Lab . Located in Pasadena, Calif., the Design ... of how hardware projects are designed, built and brought to market. , The ...
(Date:6/23/2016)... Andrew D Zelenetz ... Published recently in Oncology ... touchONCOLOGY, Andrew D Zelenetz , discusses the ... is placing an increasing burden on healthcare systems ... With the patents on many biologics expiring, interest ...
(Date:6/23/2016)... FRANCISCO , June 22, 2016  Amgen (NASDAQ: ... sponsorship of the QB3@953 life sciences incubator ... human health. The shared laboratory space at QB3@953 was ... overcome a key obstacle for many early stage organizations ... part of the sponsorship, Amgen launched two "Amgen Golden ...
Breaking Biology Technology: