Brain Reorganization

As human beings we have been raised to dream in exploring the ventures of the unknown, and for this we have accomplished many achievements. We have developed small submarine crafts capable of reaching the bottom most caverns of the ocean. We have built space shuttles and lunar landers capable of launching a man into space and landing him safely on the moon, and we have even sent probes to as far as one of Saturn’s moons. We have always reached out to discover the perplexities of the universe, but there is a reach that most of us might not have considered—our own minds. The use of the term mind is used best to describe how we think, how we feel, and how we act. Like other animals, our brain developed the same five major divisions [2], but it is our advanced cerebral cortex that sets us apart; however, scientific study, even if performed on animals other than human, can still provide great insight into the inner workings of our minds. Undoubtedly, our brain is a complex organism in itself. It contains many secrets yet to be explained. Yet, like the ocean and the ever expanding universe, our brain can best be defined as changing.

“Recent research on monkeys and other animals shows that the brain continually and dynamically reorganizes itself, even in adulthood.” [1] Since the moment we were born, our brain has been picking up stimuli and incorporating them into experiences we can later use to learn from. Our brain maintains within itself the functions of how we talk, process speech, read, write, and even sing. It regulates our every movement, but how can any of these normal processes ever be conceived as an example of how our brains are changing? The answer must first start at a better understanding of neurons.

Neurons are the basic components that make up the nervous system. Neurons and neuroglial cells are the conductors that carry the charge, the chemical signals which fire at the synaptic regions that control possibly everything we do from our memories, to our concept of selves, and how we process information in learning. The stronger the signal, the better we process it and quite the opposite for the weaker. It is unknown how these synaptic regions decode and integrate these signals, but by doing so, it is a key factor which can help to explain how our mind is able to adapt to the environment.

Plasticity is a general property of the nervous system that refers to the findings that neurons adjust their information-processing and communicative properties under a broad range of conditions. [2]

The ability of our brain to change was once thought only to happen during its development. Studies where stroke victims never fully recovered had only helped to solidify our concept [6]; however, recent new studies have been done to prove that the brain does continue changing, even as we get older, and this reorganization occurs on many levels. There are two types of reorganization that I would like to mention that are parts of a broader definition of cortical plasticity—the ability for change which can be found in the cerebral cortex.

The first type of reorganization I would like to make mention of is what I have coined as “somatosensory representation reorganization” or “SS” for short. The word somato means “body” or “of the body” and sensory means, well, the senses. Just by using your body to do something, be it pressing a button, playing the violin, or picking your nose, you are exciting your senses; If this excitation is long lasting then the representation to that bodily function is increased. This can be marked by greater synaptic responses in that area or a larger blood flow to the brain, but the representation is distinct. If I pick my nose only using my right index finger, then only my right index finger’s representation will increase. This same is also true in reverse if we neglect using something. According to Ashe [2], a good example of the “SS” in reverse is the study of “the critical period for the development of neurons with binocular responses in the visual cortex of kittens.” In this study, Ashe explains that if I were to sew a kitten’s eyelids together at a critical stage in its development, there would be a permanent change in its visual cortex which would be the difference in it having binocular or monocular vision due to weakened synaptic responses in the eyes. Use it or lose it takes a lot more literal meaning.

The second type of reorganization in cortical representation I would like to mention is “deafferentation-induced reorganization” or “DI.” Let’s say you accidentally cut your finger off—ouch. Now, although you have lost your finger, does that mean the area in the brain that responded to that finger is lost to? The answer is no, but won’t it degenerate due to un-use? The answer again is no. Our brain has ways of being able to adapt and overcome—areas that are un-used are then quickly assimilated by surrounding cortical areas. “When nerve stimulation changes, as with amputation, the brain reorganizes […] after amputation, however, neurons that formerly responded to signals from the finger respond to signals from the thumb.” [1] There exists within us from the day we were born a matrix or a network of our entire body implanted in our mind. It is quite possibly the remapping of this network that might integrate this function to take place. The response that can be felt makes lead to mentioning a phenomena called phantom limb. Phantom limb is a phenomenon in which one can feel what isn’t there anymore; however, just because you can feel it, doesn’t mean that a legless man should play soccer or an armless girl should play dodge ball.

There is a process taking place in our neurons called “Axonal Path finding,” [2] which can help to better explain how our brain’s neurons are able to reach out and extend into other regions.

Neural process destined to become mature axons and dendrites are termed neurites. Neurites grow and extend by means of growth cones [which] only form when the neurite is in contact with an appropriate substratum and they are in constant motion, moving outward and retracting back, moving to the right and to the left, reminiscent of searching motions. Once the peripheral ganglia have formed, neurons within them sprout neurites that slowly increase their length to make eventual contact with their targets. [2]

This description conjures images of how a plant’s roots seek out water in the ground moving kind of like that bean stalk in that “Mickey mouse” cartoon. This description can help to explain how, even an amputated area as large as an arm or leg can still feel responses through, say, the face [4, 5]. This only goes to raise the question of how limitless are the bounds of reorganization.

Ever since Helen Keller made it famous to study the deaf and blind, new evidence has been surmounting in those areas. It is now believed that areas of the temporal lobe in the deaf, usually incorporated for the function of listening, are in use when a deaf person utilizes sign language or reads lips [7]. It is quite possible that they can actually hear what they see. This type of reorganization is what makes the processing of sign language that much easier. The same types of advancements and discoveries have also been found in the blind [7], in the regards that they can see what they feel or hear. Areas of their occipital lobe are in use when a blind person reads braille or when listening to someone speak. The blind are also regarded as having a better vocabulary and a better ability at remembering words [3]. The cortical representations in a deaf man’s visual processes or a blind woman’s auditory processes are just some of the wonders that can be discovered through greater research.

Who knows what can be achieved if we just do further study? The more we understand how our mind functions, the better we can create new things to advance the lives of those that have suffered the loss of their sight or hearing. No matter what type of advantage that can be gained by going blind or deaf, it still does not replace what we have lost. If human beings were meant to be blind, we wouldn’t have been born with eyes, and if we were meant to be deaf, we wouldn’t have ears. Perhaps, someday, we will discover ways that we can create a practical everyday invention to restore a completely deaf woman’s hearing or a blind man’s sight. Until then, who knows?

BACK

Work Cited

1. Ariniello, L. "Brain Reorganization." Society for Neuroscience.

http://www.sfn.org/content/Publications/BrainBriefings/brain_reorg.html

2. Ashe, J., V., B. "Brain Development and Plasticity." University of California,

Riverside. Ed. Friedman, H. Encyclopedia of Mental Health. Vol 1, Academic Press:

1998.

3. Barach, J. "Reorganization Of The Brain May Provide Blind With Superior Verbal

Memory." Hebrew University of Jerusalem.

www.bioisrael.com/upload/research/blind_research.doc

4. H.-X. Qi, I. Stepniewska, and J. H. Kaas

"Reorganization of Primary Motor Cortex in Adult Macaque Monkeys With Long-

Standing Amputations." J Neurophysiol, October 1, 2000; 84: 2133 - 2147.

5. Neeraj Jain, Sherre L. Florence, Hui-Xin Qi, and Jon H. Kaas.

"Growth of new brainstem connections in adult monkeys with massive sensory loss."

PNAS, May 2000; 97: 5546 - 5550.

6. "Researchers Prove Brain Can Compensate for Damaged Regions." Office of External

Relations, Columbia University Health Sciences Division, Oct 02, 2000.

http://www.columbia.edu/cu/news/00/10/brainDamage.html.

7. Thomas, J. "Brain Reorganization." San Diego State University.