Neuroplasticity and aging: how the adult brain adapts

Neuroplasticity

This work provides a non-specialist scientific explanation of neuroplasticity. The work stresses new research and literature that supports the idea that the neural networks of the body continue to be adaptable as we age, as evidenced by research that supports neuroplasticity in the absence and presence of injury and disease in both children and adults. The work stresses that the major change in neuroplasticity between adults and children is twofold, with one being that children (infants) are more capable of major adaptive neural changes, such as reforming an entire brain area to do the work that an absent or injured primary area would have done while adults rely on more subtle reformulation and two that adult neuroplasticity seems to be lesser due to reduced need to adapt, with regard to lack of environmental exposure cues.

Neural Plasticity as we Age

Neuroplasticity and Aging

Neuroplasticity in general is the ability of the neural networks of the body to reform and change according to the environment, both external and internal to adapt to new needs and behaviors. It was once believed that the human neural networks were fundamentally set at certain developmental stages. (Reilly, Weckerly & Wulfeck, 2004, p. 39) This clearly supported biological claims that children's neural networks are far more plastic than adults, especially with regard to adaptability regarding the manner in which and the areas of the brain that garner language, sight, hearing and other major areas of development. These discoveries of adaptability coupled with the belief that there were discrete end points to how and when children learned certain major behaviors was though to make it impossible for an adult to alter these networks after he or she had reached a certain developmental level. (Reilly, Weckerly & Wulfeck, 2004, p. 40)

More recent research indicates that though Neuroplasticity is fundamentally more active in children and especially very young children and specifically regarding major developmental milestones, such as sight, hearing and language acquisition that Neuroplasticity is to some degree still very active in adults. (Willis, 2008) (Maratsos & Matheny, 1994) (Noelker, Rockwood, Sprott, & Schulz, 2006, p. 73) This then makes adult learning and behavior change possible and some neuroadaptability to exist even after brain or neuro injury or disease. Though adults recovering from neural injury or disease may adapt to do things in an entirely and sometimes unsatisfactory manner relearning is still possible following such events. "Neurons and their synapses are dynamic entities that change from millisecond to millisecond, while simultaneously imbedding information into their fabric.[3]" (Arnstein, 1997, p. 1) it has been in fact postulated that real neural degeneration does not actually occur in people as they age, as was once postulated unless disease or serious depravity is present. (Noelker, Rockwood, Sprott, & Schulz, 2006, p. 203) (Mohr, 2003)

Neuroplasticity provides humans the ability to change their behavior in response to environmental events (stimuli) and underpins their ability to learn and remember. Learning is a process that occurs when organisms take in and store information as a function of experience. The information that is stored as a result of learning is memory. Learning results in neuronal changes at the level of existing synapses and results in the development of new synapses, thereby resulting in behavioral change (Beatty, 2001; Delis & Lucas, 1996). Structural changes are thought to result at the cellular level through changes in effectiveness of existing synapses between cortical cells, through the new formation of synapses among existing cortical neurons, and through the creation of new neurons to support new memory (Schachter, 1996; Squire & Kandel, 1999). (Mohr, 2003, p. 113)

Neuroplasticity is therefore a phenomena that is as active in adults as it is in children and alternating the manner in which we challenge these connections become fundamental to continual adaptation and learning. This is true in the absence or presence of disease or injury to the neural network pathways.

A New View on the Adult Neural Network

Challenging the idea that only children can retrain their brain to adapt to new environments is the fact that neural adaptation and learning occur throughout life, at varied cellular levels. In fact it is likely the fact that children are forming major pathways for certain functioning that leaves them much more vulnerable to permanent catastrophic damage from certain exposures, at very young ages. Toxins such as lead, PCBs, alcohol and even excess or reduced glucose in utero and at very young ages profoundly effects children, where these toxins only minimally affect adults. (Hussain, Gyori, Decaprio & Carpenter, 2000, p. 827) (Becker, 2000, p. 105) (Gauger et al., 2004) (Dingemans et al., 2007) ("The Obese and Diabetic Intrauterine Environment: Long-Term Metabolic or Cardiovascular Consequences in the Offspring," 2005, p. 763) (Schmidt, 2006) (Alm et al., 2006)

Neuroplasticity Changes with Age

This is not to say that Neuroplasticity does not change as we age, what most researchers lean toward in this explanation is that stimulus for change and its frequency of exposure is the key factor in keeping the neural networks adaptable. In other words as we age there is a general tendency to reduce the number of exposures to change related stimulus. As the neural networks are formed to a large degree to produce a desired result there seems to be little reason to challenge these formations and come up with a different manner in which to do something. (Gallagher & Rapp, 1997) This alone does not create the variation that causes adults to be seen as less plastic but it does explain why many people subscribe to the idea that "you can't teach and old dog new tricks," when in reality it has been shown over and over that adults can adapt change and rework the manner in which they think and learn on a moment by moment basis the need to do so is not always present in the adult world. (White & Myers, 2001, p. 95)

In other words, as we set about to do our daily tasks, which often mirror the daily tasks of the day before, and the day before that we use the tools we have already learned. For example, the individual has developed a serviceable way to tie his or her shoes they therefore do not need to learn alternative ways to do so. Yet, when the individual is faced with a broken finger he or she must learn a new way to do the task, and in doing so they change a pathway that was previously set. Now because recovery is imminent they are likely to retain the old way of doing the task but if the finger is permanently injured then the new task process must be set. There is also some evidence that lacking major neurological damage, many of the old pathways still exist in adults as they adapt to new ways of doing things where in children they often disappear, or get used for another learning task as new pathways are formed. Yet, this is challenged in the research as well and often seen to be discrete with major learning skills rather than minor daily adaptations. (Capaldi, Robinson & Fahrbach, 1999, p. 651) Adults and children still know how to crawl after they have successfully learned how to walk they are just less likely to do so, unless for some reason they are forced to.

Possibly a better way to analogously explain the various differences between the way in which an adult (of almost any age) and a child reformulates behaviors through neuroplasticity is to describe a learning or perception task, and language is a perfect example. When a child learns his or her native language he or she develops links and pathways for understanding and communicating that language, be it Vietnamese with its clicks and strong vowels or English with its hard consonants. Children can in fact simultaneously learn more than one language and think and speak it fluently while adults must adapt the pronunciation standards and thinking patterns required for native language use to the secondary language and will likely never communicate verbally in the secondary language without a discernable accent. (Maratsos & Matheny, 1994) (Leonard, 2001, p. 158) a group of researchers and a noted neuroscientist note that the mind is in a constant state of making new neural pathways as well as "pruning" those that have proven ineffective or unneeded.

In a world with so many distractions, and with new mental maps potentially being created every second in the brain, one of the biggest challenges is being able to focus enough attention on any one idea. Leaders can make a big difference by gently reminding others about their useful insights, and thus eliciting attention that otherwise would not be paid. Behaviorists may recognize this type of reminder as "positive feedback," or a deliberate effort to reinforce behavior that already works, which, when conducted skillfully, is one aspect of behaviorism that has beneficial cognitive effect. In a brain that is also constantly pruning connections while making new ones, positive feedback may play a key functional role as "a signal to do more of something." As neuroscientist Dr. Thomas B. Czerner notes, "The encouraging sounds of 'yes, good, that's it' help to mark a synapse for preservation rather than pruning." (Rock & Schwartz, 2007, p. 10)

Creating learning pathways for both children and adults that strengthen positive behavioral and functional change is therefore essential and may be even more so for adults as the synapses and their network connections regenerate to allow them to change the manner in which they act, think and work to come to a best possible solution for a task or thought process.

Conclusion

The very fact that new technology and the adult adaptation to using it proliferates modern society is proof that neuroplasticity is not only present in adults but can be profoundly utilized to redirect the manner in which we do everyday and novel tasks. (White & Myers, 2001, p. 95) Everything from learning how to use a much more complicated washer and dryer to an adult learning how to navigate the world wide web, open and read email (something that didn't exist 50 years ago) and drive and manage a hybrid car are all proof that neuroplasticity is present and at the forefront of human development, at every age. While some argue that their three-year-old might be faster at learning how to instant message than they are at 35, this is simply because the older person also holds five or ten previously important ways to communicate with the written word that he or she has fundamentally adapted to over the years that they have been alive, not because their neural networks are not plastic. (Valenstein, 2005, p. 22)

Though some argue that the emerging developments have resulted in opportunistic adaptations for application, such as "new" educational methods or even disease treatments that stress current though preliminary understandings of learning, as it applies to assumptions about neurotransmission and/or chemical pharmacological processes, still others support the fact that neuroscience and the understanding of neuroplasticity is essential to growth and development in human change. (Rose, 2005) Neuroplasticity is in fact an emerging science that will likely change the way adults and children learn and adapt to their environment, as demonstrative change is seen in how we treat and respond to change, injury and illnesses that effect the neural networks.