Jeevitha Ramesh
“Our brains renew themselves throughout life to an extent previously thought not possible.”
Michael S. Gazzaniga
Do you know anyone who has experienced a remarkable and unexpected recovery after a stroke or a traumatic brain injury, or any other kind of brain damage? Doesn't it feel like magic?! But it isn't. It's science.
Although it seems like magic, neuroscientists, over the past few decades, have been studying hard to find out what happens in these cases. With rigorous research and breakthrough, they could finally explain this magic by discovering 'brain plasticity' or 'neuroplasticity
This blog addresses the concept and science behind neuroplasticity. In the series of two blogs, we will try to understand what it is; how it occurs; Is it beneficial or not; and if ways of improving it.
Opinions and theories on how the brain works have evolved significantly through the years. Initially, in the 1930s, many researchers believed that the brain was "fixed". But modern advances in science have made researchers understand that the brain is flexible.
During the 1960s, researchers began to explore cases of brain damage wherein older adults who suffered massive brain strokes were regaining normal brain functioning. This demonstrated that the brain was more malleable than it was initially believed.
Modern researchers have also found evidence that the brain can rewire (heal) itself after damage. Research demonstrated that the brain continues to make new neural pathways and alter existing ones by adapting to new experiences, learning added information, and making new memories.
The brain's ability to change and adapt, due to new experiences, is called brain plasticity. Also known as neuroplasticity. When we say that the brain has plasticity, we are not referring to the fact that the brain is similar to plastic. Rather, it suggests the ability of our brain to adapt continually to changes in the environment. And it is because of this we can learn quickly through experiences.
It is well known that the human brain has around 85 billion neurons. Early researchers believed that neurogenesis, or the formation of the new neurons, stopped shortly after our birth.
But today it is proved that the brain maintains the amazing potential to restructure pathways, create new connections, and, in a few cases, even create new neurons! All because of brain plasticity.
There are two main types of plasticity:
Functional plasticity
Structural plasticity
Fig 1: The two main types of neuroplasticity
With an understanding of the term ‘brain plasticity, now we shall look into its characteristics. The few defining characteristics of brain plasticity include,
The age factor:
Plasticity occurs throughout the lifetime.
But certain sorts of changes are more predominant at specific ages. For example, abilities such as new neuron growth and organization are predominant at an early age.
During later years, the loss of the rate at which neurons grow can affect our cognitive abilities that are vital for sustaining functional independence, such as memory, attention, or even learning new skills. Eventually, it may also cause a loss of balance and coordination.
The role of the environment:
Plasticity is effectively influenced by exposure to stimulating environments
For example, exposure to large vocabulary and new activities can boost the growth of myelin (the insulating layer around nerves, helps in information exchange)
Influence of genetics:
The interaction between the environment and genetics also play a major role in the brain's plasticity.
For example, several neural signals that are driving plasticity are involved in the process of activation of specific genes. Variation in human genetics might influence the expression of these plasticity-related events.
Not to forget, that brain plasticity is an ongoing process. It can happen due to continuous learning, experience, and memory formation, or even as a result of trauma to the brain. During brain injury, like a stroke, the areas of the brain related to certain functions could be damaged. For example, when a stroke affects an individual's temporal lobe, he can experience issues with communication- a condition called aphasia. But, eventually, healthy parts of the brain may take over those functions and the abilities can be restored through functional plasticity: the ability of our brain to move functions from a damaged area of the brain to undamaged areas.
The concept of brain plasticity is a very vast and complicated topic, with discoveries every day! This often challenges the existing knowledge of what we already know about the brain. The current blog has addressed brain plasticity briefly: how the concept evolved, its types, and its characteristics. In our next blog, we will try and understand the benefits, limitations, and ways to improve brain plasticity.
References
Doidge N. The Brain That Changes Itself: Stories of Personal Triumph From the Frontiers of Brain Science. New York: Viking; 2007.
Hockenbury SE, Nolan SA, Hockenbury D. Discovering Psychology. 7th ed. New York, NY: Worth Publishers; 2016.
Holland E. Brain plasticity: What is it? Chudler EH, ed. Neuroscience for Kids. The University of Washington.
James W. The Principles of Psychology. Classics in the History of Psychology. Green CD, ed. 1890.
Kolb B, Gibb R. Brain plasticity and behaviour in the developing brain. Clarke M, Ghali L, eds. Journal of the Canadian Academy of Child and Adolescent Psychiatry. 2011;20(4):265-276.