Neuroplasticity in the Intact Brain: Developmental Plasticity
Developmental plasticity refers to the significant shaping of the immature brain by life experience. Though children have more neurons and synapses (the connections between neurons) than adults, they lose a massive number of neurons and synapses during adolescence through a process referred to as pruning. This process is thought to be adaptive because it allows the central nervous system to develop greater specificity to the environmentally specific needs of the organism. Specifically, those neuronal networks which are not sufficiently used are eliminated and those frequently used expand and become more interconnected.
Plasticity early in life is greatest because many synapses and neurons have not yet been pruned. As the human child develops, neurons are pruned and the brain loses its capacity to adapt as effectively to change. For instance, children exposed to a second language as pre-adolescents are able to learn the language faster and demonstrate better pronunciation skills (i.e. no accent) than individuals who study the language later in life (i.e. late adolescence, adulthood). Moreover, if a child becomes proficient in a second language, but then abstains from speaking that language prior to adolescent pruning, he/she is at risk of losing their command of the language. This principle applies to the acquisition of other skills as well (e.g. cognitive skills).
Several studies have demonstrated that the environment can have a profound influence on brain development. Animals raised in stimulus rich environments with toys and challenging obstacles have more dendritic branching and more synapses per neuron than animals without this stimulation.
Neuroplasticity in the Intact Brain: Activity Dependent and Learning/Memory Plasticity
Sustained engagement in cognitively stimulating activities has been found to affect neural structures in humans. Functional MRI (fMRI) studies of London Cab drivers found that the right posterior parietal lobe (a region of the brain responsible for following geographic directions) was largely expanded relative to controls. The authors hypothesized that the relative size difference was due to the cabdriver’s prolonged use of this area of the brain. Moreover, there was a statistically significant correlation between the volume of brain region and the years of experience and proficiency.
In one study, healthy human subjects underwent daily practice of a complex motor task with increasing performance demands for four weeks. Functional MRI scanning revealed increased physiological activation in the areas of the brain responsible for this task. This type of intense training is part of our approach and what the Brain Power® program is engineered to do.
In a recent well-controlled study, the investigators used cognitive interventions in a geriatric population which reportedly reversed cognitive aging by 7-14 years in the area of visual concentration, reasoning and memory. The authors concluded that neuroplasticity endures across the lifespan. Consequently, even the elderly can benefit from cognitive skills training.
Neuroplasticity after a Brain Injury
The once held belief that recovery from a brain injury is limited to the first one or two years following an injury has been met with considerable challenge. Neuroplasticity research suggests that people can recover for many years, but on a continuum whereby recovery is easier and faster earlier and becomes increasingly more difficult as time progresses. Multiple studies have shown that the majority of people continue to make significant physical, cognitive, and behavioral recovery, as many as 5 years or more post traumatic brain injury.
Does cognitive skills therapy facilitate the brain’s plasticity? Evidence would suggest yes. The effectiveness of therapy is directly related to its ability to physiologically and/or structurally alter the brain. One study demonstrated that an average of 15.8 sessions of cognitive skills therapy accompanied by homework assignments in persons 2 years post injury significantly altered brain functioning as measured by neuropsychological testing and SPECT data (i.e. regional cerebral blood flow). Neural reorganization can be enhanced only through specific training, rather than general experience.
Whether young or old (general cognitive enhancement), whether the brain is intact or has not developed normally (learning disorders), or has been injured (brain injuries), research demonstrates that structural and functional changes can be promoted in the brain if one is provided intensive cognitive stimulation such as that provided by the Brain Power® program. Research also demonstrates that these changes are permanent.