Neuroplasticity: The Brain That Rewires Itself

For years a dogma prevailed, it was always thought that the brain is a fixed and unalterable organ of the body that has set parts that perform set functions. It was a preconceived notion that the brain could never alter its structure or find a new way to function if any part of the brain sustained an injury or went out of use.


According to Norman Doidge, author of “The Brain that Changes Itself”, the belief that the brain could never change and is a stoic and static organ in terms of altered functions comes from these three presumptions:


A. Inability to observe the living brain’s microscopic activities

B. Brain-damaged persons could rarely make full recoveries

C. Beginnings of modern science that use machines as a metaphor for the human brain and its functions. (Doidge, 2007)


Primarily the notion that certain body functions are controlled by certain areas of the brain, called localization of the brain, substituted the idea of the brain as an undeviating organ. (Freberg, 2006). The brain is often compared to a machine that has functions “hardwired” into it, and because a machine seldom changes itself , we assume that the brain also seldom changes itself.

Spanish Neuroanatomist and Nobel laureate Santiago Ramon y Cajal, in 1894 said that, “ the organ of thought is, within certain limits, malleable, and perfectible by well-directed mental exercise.” (DeFelipe, 2013). The APA defines neuroplasticity as “the ability of the nervous system to change in response to the experience or environmental stimulation”. (Association, n.d.). Cramer described Neuroplasticity as “the ability of the nervous system to respond to intrinsic or extrinsic stimuli by reorganizing its structure, function, and connections”. (Cramer, 2011).

'Neuro' means neuron and 'Plastic' means changeable, malleable, and modifiable, hence Neuroplasticity literally means neurons that change themselves. 


Rosenzweig, the pioneer of Neuroplasticity research, did an experiment on rats that challenged the existing idea of brain fixity. In his experiment male rats were put in two separate groups. One group, called EC rats, were put in an enriched environment ( this environment had toys with which they could play, and also received maze training), while the other group, called IC rats were put in an impoverished and deprived environment, wherein they were caged in confined spaces with no enriching equipment. The results of the experiment were astounding as they went against the then existing notion. It was found that the cerebral cortex of EC rats become thicker than IC rats by 5% after training which implies that there occurred a change in their cortex. Also, the sizes of synaptic junctions of EC rats increased significantly. (Rosenzweig, 2007). The experiment clearly shows how learning can cause real physical changes in the brain. This was the beginning of a new age for neuroplasticity. In neuroscience, it is often said that neurons that fire together, wire together and neurons out of link fail to sync. (Doidge, 2007).

The Woman who sees from her tongue


Cheryl Schiltz feels like she is perpetually falling. Whenever she tries to walk or stand without support, she feels as if an invisible force is pulling her down. If you were to see her you would think as if she is drunk. Even when she falls down on the ground, she still experiences the falling sensation, as if she is being sucked into the unknown pits of the floor. Cheryl’s problem lies in her vestibular apparatus, which is responsible for our balance and sense of orientation to space. At the age of 39, she had an operation for a hysterectomy, and post-op she was injected with gentamicin because of the infection she developed. Gentamicin, if administered in huge amounts, can cause permanent damage to the ear and the vestibular apparatus. This did permanent damage to her vestibular apparatus and Cheryl was left with just 2% function.

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Paul Bach-y-Rita, a pioneer of neuroplasticity was famous for his experiments that prove brain plasticity and made strange apparatus that have helped hundreds of people. Cheryl was one of many people who benefited from his works when he was alive. Bach-y-Rita had a very famous dialogue, “ We see with our brains, not our eyes.” (Winters, 2003).


Cheryl’s link between her vision and vestibular apparatus had been severed. This experiment will now unmask another link between her vision and balance. In his experiment with Cheryl, she was made to wear a construction worker’s hat which maps the brain on two planes and shows the movement on the computer. The other part of this is the Tongue Display, which is actually a strip of plastic that consists of electrodes that guide Cheryl. Whenever she tilts her head back, there is a tickling sensation at the back of her tongue which tells her in what direction she is tilting. If she stands straight, the tingling sensation occurs in the middle of her tongue and when she leans forward the sensation travels at the tip of her tongue. Cheryl starts to cry.


After years of struggle, she experiences a sense of freedom and normalcy. She also dances with Bach-y-Rita. How did this happen? Bach-y-Rita says, there are several reasons but the main reason behind this was the brain’s plasticity.


If you were to go from point A to B and you realize that the existing bridge between them has broken, what would you do? You would take another route. This is how the neuronal pathways in our brain work. When the link between vision and vestibular apparatus no longer works, the brain (after this experiment) appoints the charge of balance to the tongue, i.e. the tongue guides the sense of orientation by simply picking up sensations. The neuronal pathways have found another bridge, they’ve found a “secondary” pathway. The best part about Bach-y-Rita’s experiment is the fact that the sensations last even after the hat has been removed.

The sensations have a residual time, which is nothing but the unmasked “secondary” pathway getting stronger after each use. After a year, Cheryl’s “secondary” pathway became so strong that she no longer requires the hat. She finally walks and sees from her tongue.


Where does the baby ferret see from?


Mriganka Sur, a neuroscientist, rewired the brain of a baby ferret. Usually, the optic nerves report all the sensations to the visual cortex. Sur surgically rewired/redirected the optic nerves from the ferret’s visual cortex to its auditory cortex and discovered that the ferret could still see. Although the ferret had a 20/60 vision, it could see (any person who wears glasses has around the same vision). By inserting electrodes in the ferret's brain, neurons in the auditory cortex fired and were doing the visual processing. The auditory cortex being plastic in nature reorganized itself to have the structure of the visual cortex, which proves the brain’s plasticity. (Mriganka Sur, September 1992)


Thinking the way through Neuroplasticity


Neuroscientist Alvaro Pascual-Leone conducted an experiment at one of the labs of Harvard’s Medical School, wherein students were divided into two groups. One group had to take piano lessons for 2 hours every day, for five days after. After the lesson they sat beneath a coil and took the TMS test, where using Transcranial Magnetic Resonance, Pascual-Leone's team tried to map the motor cortex to see which all parts were involved in the finger movements. After 5 days, the TMS revealed astonishing results. The stretch of motor cortex used in the finger movements had spread all over the neighboring areas and thereby expanded what we call, the “cortical real estate”. Pascual-Leone took the study further by assigning a similar task to the other groups of students. They just had to imagine the finger movements while a piano tune played and had to mentally imagine the piano practice. This led to another revolutionary discovery, the mere thought of playing a piano had caused real alterations in the physical structure and the function of the gray matter. Simply speaking the TMS data of both participants from both the groups came out to be the same. "Mental practice resulted in a similar reorganization" of the brain, Pascual-Leone later wrote, thereby showing that brain plasticity is complex. (Begley, 2007)




The Woman who changed her mind (Literally)


As a child, Barbara Arrowsmith-Young was described as “retarded”, because she was extremely slow as compared with children of her age. Asymmetry describes Barbara’s mind and body while growing up. She had areas of brilliance coinciding with areas of retardation. She had ninety-ninth percentile on auditory and visual memory tests and had exceptionally developed frontal lobes. But with virtues came vices. Her speech was impaired because her Broca’s area wasn’t functioning properly, she lacked spatial reasoning and would often misjudge space around her.


She also had a visual disability and had to keep everything in front of her in order to see, had a decreased sense of touch on her left side, and was dyslexic. The part of her brain that understands relationships between symbols wasn’t functionally normal. She could remember but not understand. She knew that 2+2=4 but how was a mystery for her. She described her life as fog and was unable to grasp even the meaning of what the other person was saying and hence had no friends or relationships.


When she reached into college, she stumbled upon Rosenzweig’s research along with Russian neuroscientist, Aleksander Luria’s works. She discovered that Luria had a patient named Lyova Zasetsky who had a bullet injury in his head, which had damaged the part that helped him understanding. Barbara had found her solution. For months after months, she would toil and found her own breakthrough when she made exercises for her brain. She realized that she could guess the time from the face of a clock but could not tell the time when she was asked to, i.e. she always went the other way around. She designed a number of cognitive exercises for herself, which included a range of practice puzzles and much more. And after practicing them over and over, suddenly everything made sense. Barbara says “This was in 1978, long before the concept of “neuroplasticity” was widely understood. At the time, the scientific community believed this kind of transformation was impossible, but the exercises did indeed radically improve my functioning in very specific ways. Today, this notion of brain plasticity—which I began exploring three decades ago—is established wisdom in neuroscience.” She changed her mind, literally and continues to provide hope to many other children who suffer from such learning incapabilities. The Arrowsmith Program and School are a living testimony of Barbara’s triumph over herself and millions of students still discover themselves here. (Arrowsmith-Young, 2012)



Conclusion


In recent years there have been revolutionary discoveries that have changed the way we look at the brain’s functions. Without being dependent on medications or operations many people have discovered the unknown facets of the brain that have produced history-altering results. All of this stands as a testimony to the new sensation of neuroscience known as, Neuroplasticity. It has always existed and will continue to do so.


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A friendly reminder: We've done our research, but you should too! Check our sources against your own and always exercise sound judgment.


Arrowsmith-Young, B. (2012). The Woman Who Changed Her Brain. New York, United States of America : Simon and Schuster.

Association, A. P. (n.d.). APA Dictionary of Psychology . Retrieved from American Psychological Association : dictionary.apa.org/neural-plasticity

Begley, S. (2007, January 19 ). The Brain: How The Brain Rewires Itself. Retrieved from Time Magazine: http://content.time.com/time/magazine/article/0,9171,1580438-1,00.html

Cramer, S. C. (2011). Harnessing Neuroplasticity for Clinical Applications. Pubmed.
DeFelipe, J. (2013). Going to School to Sculpt the Brain . Frontier : for Young Minds, 2.

Doidge, N. (2007). The Brain that Changes Itself. United States of America: Penguin Books.

Freberg, L. A. (2006). Discovering Biological Psychology, Second Edition. United States of America: Wadsworth Cengage Learning .

Mriganka Sur, A. W. (September 1992). Visual Projections Routed to the Auditory Pathway in Ferrets. The Journal of Neuroscience.

Rosenzweig, M. R. (2007). Modification of Brain Circuits through Experience. In F. Bermudez-Rattoni, Neural Plasticity and Memory : From Genes to Brain Imaging (p. Chapter 4). United States of America: CRC Press, Taylor and Francis Group.

Winters, M. A. (2003, June 1). Discover Magazine. Retrieved from Can You See With Your Tongue?: https://www.discovermagazine.com/mind/can-you-see-with-your-tongue

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About The Author


Bharavi Yadav

Guest Author (New Delhi, India)


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