Navigation Links
Sensory Input Necessary During "Critical Periods" Of Brain Development

The mysteries of the brain are yet to be fully solved, but scientists are aware that there is a need for some sort of neural activity for the brain to mature during //the "critical period" when it is necessary that there is a fair degree of sensory input. Scientists say that the senses of vision, hearing and touch develop during such critical periods.

The visual system provides an exemplary model for studying developmental plasticity, however, because of the pioneering work of Nobel prize-winning HMS researchers David Hubel and Torsten Wiesel describing the visual system's structure, prerequisite knowledge for investigating its flexibility. Although visual plasticity has been studied for over 40 years, exactly how sensory experience interacts with the built-in machinery that permits the brain to change its circuits is only beginning to be understood.

A new study focusing on the molecular roots of plasticity has found that visual stimulus turns up the expression of some genes and turns down the expression of others, somewhat like a conductor cueing the members of an orchestra. The study also found that during different stages of life in rodents, distinct sets of genes spring into action in response to visual input. These gene sets may work in concert to allow synapses and neural circuits to respond to visual activity and shape the brain, reports the May issue of Nature Neuroscience.

The investigators' identification of many distinct sets of activity-dependent genes follows a shift in neuroscience research toward a more holistic view of the role of genes in neural development and plasticity.

"What we found opens science up to a more global look at genes, from studying one gene at a time to looking at families of genes acting together," said first author Marta Majdan, Harvard Medical School research fellow in neurobiology. These findings suggest that genetic therapies for neurodegenerative diseases, some of which are largely limited to treatment focused on a single gene, will require more extensive knowledge of molecular pathways and gene interactions to be successful.

Majdan and co-author Carla Shatz, department chair and HMS Nathan Marsh Pusey Professor of Neurobiology, studied rodents during the critical period in which visual input stimulates aggressive plasticity, shaping the mesh of neural connections in the cortex and tuning the strengths of messages relayed by synapses. In mice, this period begins shortly after they open their eyes and begin to see. Previous research had determined that visual activity changes the level of expression of, or regulates, individual genes such as Brain-derived neurotrophic factor (Bdnf).

To determine whether vision regulates other genes in these rodents, Majdan and Shatz imposed abnormal visual experiences on the rodents at a variety of ages including the critical period by removing one eye and leaving the other intact. They then compared gene expression profiles of the cortex supporting the open eye to that of the missing eye. They found that Bdnf is not alone-visual input changes the levels of expression of ten additional genes, dubbed the "common set," at all ages investigated. By chemically inhibiting a MAP kinase already known to be linked to several common set genes, they found that this kinase acts as a relay, regulating these genes in response to visual activity.

The researchers found other sets of genes superimposed on this core pathway, but these sets are turned on and off by vision at specific ages before, during and after the critical period and into adulthood.

"This suggests that sensory experience regulates different genes in your brain depending on your age and past experience," said Shatz. "Thus, nurture, our experience of the world via our senses, acts through nature, sets of genes, to alter brain circuits."

These discoveries may lead to new ways of thinking about genetic thera pies to correct early vision disorders. Because the brain is so altered by abnormal vision, restoring vision to a child afflicted with cataracts or strabismus, an eye misalignment which can impair vision, may not be enough to correct the damage. Nor will treatment involving single gene replacement.

"We need to try to find the major switches that turn on genes in the downstream network as opposed to looking at each element of the network and designing therapy based on each gene," said Shatz.

This study helps explain why it is that children learn so quickly and easily, and it lends credence to the idea that, in adults, mental activity leads to mental agility.

"It is amazing that, even in our oldest mice we saw genes regulated by vision. Genes in the brain change with experience at every age, forming a basis for our ability to learn and remember even in adulthood," said Shatz.

This research was supported by grants from the U.S. National Institutes of Health to Shatz, and by Canadian Institutes of Health Research and Harvard Medical School Berenberg Fellowships to Majdan.

Contact:
Beth Dougherty or Judith Montminy,
Harvard Medical School,
617-432-0442 (public_affairs@hms.harvard.edu)
Source: Eurekalert

'"/>




Related medicine news :

1. Chemical Signaling Helps Regulate Sensory Map Formation In The Brain
2. Brain Filters Sensory Information
3. Knowledge Of Infertility Gets New Inputs
4. Patients Are Given Catheter Longer Than Necessary
5. Transparency in Probable Outcomes of Cosmetic Surgeries Necessary
6. Adequate Ground Work before a Pandemic Necessary
7. Oral Polio Vaccine Necessary for Haj Pilgrims
8. Is Prior Testing Necessary For Diagnosis And Treatment Of Fecal Incontinence (FI) ?
9. Special Diets Necessary for Those Undergoing Chemotherapy
10. No Carrier Necessary: This Drug Delivers Itself
11. Oxygen Usage During Exercise Could Indicate Heart Problems
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:6/27/2016)... ... 27, 2016 , ... TherapySites, the leading website ... Tennessee Counseling Association. This new relationship allows TherapySites to continue to ... adding exclusive benefits and promotional offers. , "TCA is extremely excited about this ...
(Date:6/27/2016)... ... June 27, 2016 , ... A revolution ... the emergency ambulance transport experience for the millions of people who require these ... disrupted the taxi industry through the use of technology. Now, SmartEMS has put ...
(Date:6/26/2016)... PLAINSBORO, N.J. (PRWEB) , ... June 27, 2016 , ... ... same sources, yet in many ways they remain in the eye of the beholder, ... Oncology (EBO), a publication of The American Journal of Managed Care. For the full ...
(Date:6/26/2016)... ... June 26, 2016 , ... Pixel Film Studios Released ProSlice Levels, a ... can give their videos a whole new perspective by using the title layers ... Film Studios. , ProSlice Levels contains over 30 Different presets to choose from. ...
(Date:6/26/2016)... NC (PRWEB) , ... June 26, 2016 , ... Brent Kasmer, a legally blind and ... to be personalized through a fitness app. The fitness app plans to fix the two ... currently only offer a one size fits all type program , They don’t ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... Mass. , June 24, 2016   ... Spaulding Rehabilitation Network,s Dean Center for Tick ... Physical Medicine and Rehabilitation, MIT Hacking Medicine, University ... for Innovation, today announced the five finalists of ... for Lyme disease.  More than 100 scientists, clinicians, ...
(Date:6/24/2016)... and SAN CLEMENTE, Calif. , June ... -based mobile pulmonary function testing company, is now able to ... devices developed by ndd Medical Technologies , Inc. ... done in hospital-based labs.  Thanks to ndd,s EasyOne PRO ® , ... , can get any needed testing done in the comfort of ...
(Date:6/24/2016)... , June 24, 2016  Arkis BioSciences, ... less invasive and more durable cerebrospinal fluid treatments, ... funding.  The Series-A funding is led by Innova ... Fund, and other private investors.  Arkis, new financing ... instrumentation and the market release of its in-licensed ...
Breaking Medicine Technology: