RxPG News Feed for RxPG News

Medical Research Health Special Topics World
  Home
 
   Health
 Aging
 Asian Health
 Events
 Fitness
 Food & Nutrition
 Happiness
 Men's Health
 Mental Health
 Occupational Health
 Parenting
 Public Health
 Sleep Hygiene
 Women's Health
 
   Healthcare
 Africa
 Australia
 Canada Healthcare
 China Healthcare
 India Healthcare
 New Zealand
 South Africa
 UK
 USA
 World Healthcare
 
   Latest Research
 Aging
 Alternative Medicine
 Anaethesia
 Biochemistry
 Biotechnology
 Cancer
 Cardiology
 Clinical Trials
 Cytology
 Dental
 Dermatology
 Embryology
 Endocrinology
 ENT
 Environment
 Epidemiology
 Gastroenterology
 Genetics
 Gynaecology
 Haematology
 Immunology
 Infectious Diseases
 Medicine
 Metabolism
 Microbiology
 Musculoskeletal
 Nephrology
 Neurosciences
  Brain Diseases
  Demyelinating Diseases
  Headache
  Memory
   Intelligence
  Neurochemistry
  Neurodegenerative Diseases
  Regeneration
  Spinal Cord Diseases
  Stroke
  Taste
  Trigeminal Neuralgia
 Obstetrics
 Ophthalmology
 Orthopedics
 Paediatrics
 Pathology
 Pharmacology
 Physiology
 Physiotherapy
 Psychiatry
 Radiology
 Rheumatology
 Sports Medicine
 Surgery
 Toxicology
 Urology
 
   Medical News
 Awards & Prizes
 Epidemics
 Launch
 Opinion
 Professionals
 
   Special Topics
 Ethics
 Euthanasia
 Evolution
 Feature
 Odd Medical News
 Climate

Last Updated: Oct 11, 2012 - 10:22:56 PM
Memory Channel

subscribe to Memory newsletter
Latest Research : Neurosciences : Memory

   EMAIL   |   PRINT
How the Brain Loses Plasticity of Youth

Aug 18, 2006 - 6:51:00 PM , Reviewed by: Himanshu Tyagi
"Our discovery underscores further the fascinating and common molecular parallels between the nervous system and the immune system, where PirB was first studied. The discovery of a neuronal receptor for MHC Class I opens up a completely new avenue for thinking about broader roles for this family of molecules beyond the immune system"

 
[RxPG] A protein once thought to play a role only in the immune system could hold a clue to one of the great puzzles of neuroscience: how do the highly malleable and plastic brains of youth settle down into a relatively stable adult set of neuronal connections? Harvard Medical School researchers report in the August 17 Science Express that adult mice lacking the immune system protein paired-immunoglobulin like receptor-B (PirB) had brains that retained the plasticity of much younger brains, suggesting that PirB inhibits such plasticity.

Intriguingly, brains of immature PirB-deprived mice also exhibited greater plasticity than brains endowed with the protein. Taken together, the results have important implications for the future study and repair of the brain. "Our study of mutant mice lacking PirB function reveals that at all ages, even during critical periods when circuits are prone to change, there are active molecular mechanisms that function to limit synaptic plasticity," said Josh Syken, HMS instructor in neurobiology and lead author of the study.

One way to promote new connections in brains damaged by disease or injury might be to target PirB. "The implications here should attract broad interest outside the field of developmental neuroscience because molecules and mechanisms that oppose neuronal plasticity represent new targets for therapy to re-establish damaged connections following spinal cord injury, head injury or stroke," said Syken, who carried out the study with Carla Shatz, Nathan Marsh Pusey professor of neurobiology at HMS, and colleagues.

Plasticity, the ability of functional brain circuits to change in response to experience-dependent neuronal activity, is largely restricted to critical periods of development. In their classic Nobel-prize winning experiments, David Hubel and Torsten Weisel showed that visual areas of the brain are responsive to environmental cues during a discrete period early in life, after which they do not change. Researchers have successfully identified proteins that promote such critical periods of plasticity but less is known about the proteins that stabilize neuronal connections.

Several years ago, Shatz and colleagues made the surprising discovery that MHC Class I genes are turned on in neurons by neuronal activity and in fact are required for normal synaptic plasticity. In the immune system, MHC Class I proteins teach immune cells which cells to attack. They do this by interacting with a large number of receptors found on the surface of immune cells. Syken, Shatz and colleagues wondered whether such receptors might also be expressed in neurons and involved in MHC Class I-mediated synaptic plasticity.

Using a method called in situ hybridization, they found that the MHC Class I receptor PirB is expressed widely throughout the brain and at all ages. To see how PirB was functioning, they generated a mouse deficient in PirB. At first sight, the mutant's brain appeared normal. To get a better sense of how PirB might be affecting plasticity, they decided to focus on the visual cortex.

In their earlier work, Hubel and Weisel showed that suturing or removing one eye causes projections from the remaining eye to invade the area that normally represents the blocked eye. This shift is strictly limited to a critical period of development early in life. Syken and his colleagues sutured one eye in their adult mutant mice, and also in controls, for several days. They exposed the open eye to light and, using the activity-sensitive gene Arc as their guide, looked to see which neurons in the cortex were activated. The PirB mutant adults exhibited a robust expansion of the area in visual cortex that responds to the open eye, suggesting that new connections representing the open eye had formed. They repeated the experiment with younger mice and found, somewhat unexpectedly, that plasticity was enhanced even during the immature period.

"Other factors have been shown to restrict plasticity after the critical period, but we believe that this is one of the first proteins shown to act in this way throughout life," Syken said. "Our discovery implies that there are mechanisms that enable, and also those that oppose synaptic plasticity in a push-pull fashion."

"Our discovery underscores further the fascinating and common molecular parallels between the nervous system and the immune system, where PirB was first studied. The discovery of a neuronal receptor for MHC Class I opens up a completely new avenue for thinking about broader roles for this family of molecules beyond the immune system," he said.



Publication: August 17 Science Express
On the web: www.hms.harvard.edu 

Advertise in this space for $10 per month. Contact us today.


Related Memory News
Enriched environment as a child helps reverse memory problem
How brain pacemakers erase diseased messages
Relational memory requires time and sleep
Phase locking of hippocampal interneuron membrane potential
Poor memory could signal heart disease
Memories: It's all in the packaging
Atrial Fibrillation linked to Reduced Cognitive Performance
Human Memory Gene Identified
How the Brain Loses Plasticity of Youth
Apple Juice Inproves Memory By Boosting Acetylcholine Production

Subscribe to Memory Newsletter

Enter your email address:


 Additional information about the news article
Harvard Medical School has more than 7,000 full-time faculty working in 10 academic departments housed on the School's Boston quadrangle or in one of 48 academic departments at 18 Harvard teaching hospitals and research institutes. Those Harvard hospitals and research institutions include Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Cambridge Health Alliance, The CBR Institute for Biomedical Research, Children's Hospital Boston, Dana-Farber Cancer Institute, Forsyth Institute, Harvard Pilgrim Health Care, Joslin Diabetes Center, Judge Baker Children's Center, Massachusetts Eye and Ear Infirmary, Massachusetts General Hospital, Massachusetts Mental Health Center, McLean Hospital, Mount Auburn Hospital, Schepens Eye Research Institute, Spaulding Rehabilitation Hospital, and the VA Boston Healthcare System.
 Feedback
For any corrections of factual information, to contact the editors or to send any medical news or health news press releases, use feedback form

Top of Page

 
Contact us

RxPG Online

Nerve

 

    Full Text RSS

© All rights reserved by RxPG Medical Solutions Private Limited (India)