Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. Earth Science News .




ABOUT US
Finding the way to memory
by Staff Writers
Montreal, Canada (SPX) Feb 08, 2013


Guidance proteins regulate brain plasticity.

Our ability to learn and form new memories is fully dependent on the brain's ability to be plastic - that is to change and adapt according to new experiences and environments. A new study from the Montreal Neurological Institute - The Neuro, McGill University, reveals that DCC, the receptor for a crucial protein in the nervous system known as netrin, plays a key role in regulating the plasticity of nerve cell connections in the brain. The absence of DCC leads to the type of memory loss experienced by Dr. Brenda Milner's famous subject HM.

Although HM's memory loss resulted from the removal of an entire brain structure, this study shows that just removing DCC causes the same type of memory deficit. The finding published in this week's issue of Cell Reports, extends Dr. Milner's seminal finding to another level, revealing a key part of the molecular basis for learning and memory.

Although both netrin and DCC are essential for normal development (in terms of guiding nerve cell growth) until now their function in the adult brain was not known. Dr. Tim Kennedy, lead researcher and neuroscientist at The Neuro, contributed to the discovery of netrins as a young post-doctoral fellow. This new study reveals the answer to the question that drove him to first start a lab.

"I remember that exact moment when I knew I could run a research lab, it was 1993 and I was studying the developing nervous system and I was amazed to spot netrins in the adult brain - raising the important question, 'what are they doing there?' 20 years of dedicated research later the answer provides an important piece of the puzzle for understanding our nervous system and neurological disorders.

"The power of this study is that it looks at the animal on all levels, molecular, structural, and behavioural. We show that the netrin receptor DCC is a critical component of synapses between neurons in the adult brain, and is required for synapses to function properly.

To demonstrate this, we selectively removed DCC from a specific subset of neurons in the adult mouse brain. This results in progressive degeneration of synapses, leading to defects in synaptic plasticity and memory. The synapses continue to function in that they still communicate but, the synapses cannot adjust or change in response to new experiences. Therefore, you can't learn anymore."

Furthermore, DCC deletion from mature neurons results in changes in the shape of specialized protrusions called dendritic spines, and alters the NMDA receptor, a critical trigger for mechanisms that make changes in synaptic strength. Therefore the study reveals that DCC is required to maintain proper synapse morphology or shape, and to regulate the ability of the NMDA receptor to switch on, which ensures activity-dependent synaptic plasticity.

Mutant mice that entirely lack DCC in all cells do not survive past birth and exhibit major defects in brain development. In order to investigate the function of netrin in the adult brain, researchers from the Netherlands Cancer Institute, collaborators on this study, engineered a new strain of floxed mice, in which the DCC gene can be selectively deleted from a specific sub-set of cells. Floxing involves putting short sequences of DNA on either side of a gene sequence.

An enzyme that is activated later in life then recombines the DNA and cuts out the intervening sequence - deleting the gene only from specific cells. The Kennedy lab activated this enzyme only in the mature mouse brain, and limited activation to only a subset of neurons, consequently deleting the DCC gene from only from these neurons.

These mice live to adulthood (DCC is made normally in all other cells in the mouse) as the enzyme only turns on and deletes DCC in specific cells in the adult brain. Although the mice otherwise appear normal, testing their behavior revealed severe deficits in their ability to form certain types of new long-term memories.

This study provides important new insight into the neural mechanisms of learning and memory, processes that are fundamental to our existence, survival, and everyday life.

This research was funded by the Canadian Institutes of Health Research. Dr. Kennedy is a Chercheur national of the Fonds de recherche du Quebec - Sante and a Scholar of the Killam Trusts. Link to paper published this week in Cell Reports.
.


Related Links
Montreal Neurological Institute
All About Human Beings and How We Got To Be Here






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





ABOUT US
3D printing breakthrough with human embryonic stem cells
London, UK (SPX) Feb 06, 2013
A team of researchers from Scotland has used a novel 3D printing technique to arrange human embryonic stem cells (hESCs) for the very first time. It is hoped that this breakthrough, which has been published in the journal Biofabrication, will allow three-dimensional tissues and structures to be created using hESCs, which could, amongst other things, speed up and improve the process of drug ... read more


ABOUT US
HDT Global Awarded Guardian Angel Air-Deployable Rescue Vehicle Contract

Sri Lanka rescues 138 stranded on sinking boat: navy

Munich Re says profits quadrupled in 2012

NGO ends Mozambique flood aid over graft: report

ABOUT US
Largest prime number to date found

South Korean Satellite Makes First Contact with Ground

Novel materials shake ship scum

Penn Research Shows Mechanism Behind Wear at the Atomic Scale

ABOUT US
Increases in extreme rainfall linked to global warming

Lake Mead Aquatic-Science Research Documents Substantial Improvements in Ecosystem

Russia claims record dive but no monster in deep freeze

2 Great Lakes at record low levels

ABOUT US
Polar bear researchers urge governments to act now and save the species

Cyclone did not cause 2012 record low for Arctic sea ice

NSF-funded Team Samples Antarctic Lake Beneath the Ice Sheet

Norway's ruling party may back Arctic islands oil drive

ABOUT US
How plant communities endure stress

Chocolate not yet China's cup of tea

Minnesota cancels moose season

How plants sense gravity - a new look at the roles of genetics and the cytoskeleton

ABOUT US
Heavy rain kills 34 in Pakistan: officials

Scramble to reach tsunami-hit villages in Solomons

Five dead as 8.0 quake off Solomons sparks Pacific tsunami

Osaka Basin map: Identifies high-rise buildings at risk from quakes

ABOUT US
Ghana extradites ex-military chief to I. Coast: security

Sudan president in Eritrea after Asmara mutiny: reports

Central African rebels warn president over peace deal

DR Congo peace deal signing cancelled: UN

ABOUT US
Finding the way to memory

New Geology study raises questions about long-held theories of human evolution

3D printing breakthrough with human embryonic stem cells

Alternate walking and running to save energy, maintain endurance




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement