Brain Plasticity simply refers to the capacity of the Central Nervous System to adapt or change after environmental stimulation.

Behavioral Plasticity and Recovery of Function

For developing brains there exist critical periods in which the effects of brain trauma will often cause delayed or impaired development. Recovery from these situations is possible if the child or adult undergoes a neurodevelopment training program. The principle takes into account the brain's ability to recover due to the plastic nature of the brain and focuses on developing cognitive functional abilities.

For adults the same response to trauma applies, but recovery is different due to maturation of the brain. Recovery for adults should be viewed as return of previously developed function.

The mechanism for recovery has been discussed in the medical literature for over 200 years.

Developmental Plasticity

Studies of neural connections indicate that afferent cells after damage can produce new connections based upon a process called synaptic reorganization. This discovery forms the bases for brain plasticity (Brauth,et al 1991; Gazzaniga,et al, 1979). Three forms of synaptic reorganization have been observed:

1. Sprouting
2. Spreading
3. Extension

Sprouting of new axons increases the number of terminals in the normal dendrite area. Spreading is the development of terminals in the new target area and Extension refers to the termination of afferents on cells that are not the normal target areas.

Denervation supersensitivity states that after damage the remaining fibers may become overly sensitive to neurotransmitters and activate pathways that will result in the return of function.

Both concepts require the brain and supporting nervous system to be externally stimulated in order for recovery to occur. The brain plasticity concept requires five important factors to be present at all times:

1. Environmental Stimuli
2. Frequent Stimulation
3. Proper Duration of Stimulation
4. Motivation or intensity
5. Consistency

Brain Plasticity and Brain Repair
Author: Roberta Friedman
Source: Society of Neuroscience Conference
Abstract

New research is now indicating the glial cells that most neuroscientists have regarded as merely support cells in fact take an active role in building the brain and perhaps can be tapped into for making repairs.

A primitive type of glial cell serves as the stem cells that actually generate the brain's neurons. Even in adults, these glial cells can form new neurons scientists are finding.

This further supports the brain plasticity concept that the brain will attempt to repair itself until the day we die.

Controlling the Critical Period of Plasticity
Date: May 2003
Author: Takao K. Hensch

Abstract
Neuronal circuits are shaped by experience during 'critical periods' of early postnatal life. The ability to control the timing, duration, and closure of these heightened levels of brain plasticity has recently become experimentally possible.

Two seemingly opposed views of critical period mechanism have emerged: (1) plasticity may be functionally accessed throughout life by appropriately modified stimulation protocols, or (2) plasticity is rigidly limited to early postnatal life by structural modifications.

This overview synthesizes both perspectives across a variety of brain regions and species. A deeper understanding of critical periods will form the basis for novel international efforts to ''nurture the brain''.

Brain Plasticity, Language Processing and Reading
Source: Society for Neuroscience Publication

Many scientists once believed that as we aged the brain's networks cemented in place. But now an enormous amount of evidence uncovered in the past two decades finds that the brain never stops changing and adjusting. One line of research is showing that this flexibility can help maintain language processing even in the face of severe obstacles. Futhermore, some research suggests that special brain exercises can tap into the brain's adaptive capacities and help people overcome certain language and reading problems.

People who lose their eye-sight do not have to rely on audio novels to fulfill a book obsession. They can learn to read compositions in Braille, a writing composed of raised dots arranged in specific patterns, with their fingertips.

It's one of the benefits of having a plastic brain. That doesn't mean your brain is molded from a high-molecular-weight polymer similar to your toothbrush. It means that the brain is flexible. It compensates for obstacles. It adapts. It adjusts.

Once, researchers believed that only young brains were plastic. They thought that the connections between the brain's neurons developed in the first few years of childhood. Then they became fixed and very hard to change. An enormous amount of animal and human data uncovered in the past two decades, however, confirms that the brain retains its plasticity throughout life.

One line of research provides evidence that older brains can adapt in order to overcome a number of barriers and aid language processing and reading. The new findings are leading to:

1. A better understanding of the many different ways that the brain can process language.
2. Clearer ideas on how children and adults naturally can overcome language-processing obstacles.
3. Insights into how strategies may reroute brain networks and help those with reading, speech or hearing disabilities.
4. Ways to help second-language learners recognize new language sounds and to eliminate accents.

An increasing number of studies detail how the brain naturally reorganizes to overcome language and reading obstacles. For example, one new experiment shows how young and old brain networks modify to handle a loss of sight and process Braille. Researchers photographed the brain activity of individuals who lost their sight either as infants or after age 10 while they thought of a verb that related to a Braille-embossed noun. Like sighted people, the blind activated three brain areas thought to relate to language processing. Those who had been blind since infancy also received some help from the brain areas that normally process visual information in sighted people. Those who had been blinded later in life snagged some extra help from a few of the brain's visual areas as well as the brain's touch areas.

The study shows the brain's ability to readjust its circuits to process language -- at any age. It also backs the idea that special brain exercises could tap into the brain's adaptive capacities when it can't do it on its own and could help people regain language functions despite various deficits.

Individuals with the reading disabiltiy, dyslexia, are one group that may benefit from these exercises. Studies show that different types of training techniques sometimes can improve dyslexics' poor reading skills. Many scientists believe that these techniques rework failing language processing networks.

Researchers now are photographing brains before and after intervention trainings to see if this is the case. Once they catalog the changes, they may be able to pair certain interventions with certain forms of dyslexia.

Adults who learn second languages also may benefit from interventions that are thought to take advantage of brain plasticity. Often, adults have trouble hearing and pronouncing certain non-native sounds. Japanese individuals, for example, can't hear or pronounce the difference between the "r" and "l" English sounds. The words "read" and "lead" sound the same to Japanese individuals. Studies have found, however, that special training techniques can help them overcome this setback. A recent study found that one training approach resulted in improvements in Japanese adults' perception and production of English words with "r" and "l" sounds. The improvements lasted for at least three months.

Many researchers think that training techniques sometimes can help those with the reading disability, dyslexia, because they modify brain networks. One case shows the brain activity of a 10 year-old boy while he completes a task that requires the ability to identify the sounds of words. His reading level equaled that of an eight-year-old child. After receiving eight weeks of a type of special training, his reading level increased by three years and his brain activity changed as well. Researchers are conducting a very large, ongoing study to confirm this one example.