PLASTICITY WITHIN THE BRAIN

Introduction

Neuroplasticity, or brain plasticity, refers to the brain’s ability to CHANGE throughout life. The human brain has the amazing ability to reorganize itself by forming new connections between brain cells (neurons).  In addition to genetic factors, the environment in which a person lives, as well as the actions of each person, play a significant role in plasticity.

 

Neuroplasticity occurs in the brain:

1- At the beginning of life: when the immature brain organizes itself.

2- In case of brain injury: to compensate for lost functions or maximize remaining functions.

3- Through adulthood: whenever something new is learned and memorized

 

Plasticity - learning how to read.

Brains are constantly reorganising themselves. Any time we learn a new skill, connections between neurons that allow us to perform that skill become stronger. This flexibility is heightened during childhood, which is why so much learning gets crammed in before adolescence.

 

As a child becomes literate, there is no “reading centre” that magically materialises in the brain. Instead, a network of connections develops to link existing areas that weren’t previously linked. Reading becomes a way of accessing language by sight, which means it builds on architecture that is already used for recognising visual patterns and understanding spoken language.

 

When a skilled reader encounters a printed word, that information travels from their eyes to their occipital lobe (at the back of the brain), where it is processed like any other visual stimulus.  From there, it travels to the left fusiform gyrus, otherwise known as the brain’s “letterbox”. This is where the black squiggles are recognised as letters in a word. The letterbox is a special stopover on the word’s journey because it only develops as the result of learning to read. It doesn’t exist in very young children or illiterate adults, and it’s activated less in people with dyslexia, who have a biological difference in the way their brains process written text.  Words and letters are stored in the letterbox – not as individually memorised shapes or patterns, but as symbols. This is why a skilled reader can recognise a word quickly, regardless of font, cAsE, or typeface.  Information then travels from the letterbox to the frontal and temporal lobes of the brain, to work out word meaning and pronunciation. These same areas are activated when we hear a word, so they are specialised for language, rather than just reading and writing.

 

Because information can travel so quickly across the skilled reader’s synaptic highways, the entire journey takes less than a half second.  But what happens in the brain of a five-year-old child, whose highways are still under construction?

 

For young children, the process of getting from print to meaning is slow and effortful. This is partly because beginning readers have not yet built up a store of familiar words that they can recognise by sight, so they must instead “sound out” each letter or letter sequence.  Every time children practise decoding words, they forge new connections between the visual and spoken language areas of the brain, gradually adding new letters and words to the brain’s all-important letterbox.  Remember, when a practised reader recognises a word by sight, they process the letters in that word, rather than its shape.  Literacy instruction can therefore support children’s learning by highlighting the symbolic nature of letters - in other words, by drawing attention to the relationships between letters and speech sounds.

Changes associated with learning occur mostly at the level of connections between neurons: New connections form and the internal structure of the existing synapses change. 

 

For a long time, it was believed that as we aged, the connections in the brain became fixed, and then simply faded. Research has shown that in fact the brain never stops changing through learning. Plasticity is the capacity of the brain to change with learning.

 

Recent research, which took place in India where illiteracy remains roughly 39 percent, challenges that assumption. For the study, Huettig and colleagues recruited 30 illiterate, Hindi-speaking adults from two small villages in North India and scanned their brains with functional magnetic resonance imaging (fMRI), which detects blood flow to specific brain regions. They then taught 21 of these participants how to read Hindi over the course of six months, and scanned their brains once again. They found that, compared to both the earlier scans and the later scans of the nine participants who did not learn how to read, the 21 participants experienced fundamental changes, even within their deepest brain structures.

“We observed that the so-called colliculi superiores, a part of the brainstem, and the pulvinar, located in the thalamus, adapt the timing of their activity patterns to those of the visual cortex”, Michael Skeide, also of the Planck Institute, said in a press release. “These deep structures in the thalamus and brainstem help our visual cortex to filter important information.”

 

The results suggest that, whether you’re teaching your kid to read for the first time, or brushing up on your own reading skills, practice makes perfect—and, in this case, practice fundamentally changes your brain.

 

“Our study suggests that reading experience is really important and that reading should be encouraged as much as possible and practiced as much as possible in both children and adults,” Huettig told Fatherly. “In other words, the more both children and adults read the better.

 

                    

 

Plasticity and brain injury.

A surprising consequence of neuroplasticity is the fact that the brain activity associated with a given function can actually move to a different location as a consequence of experience or brain damage.

 

In his book “The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science,” Norman Doidge describes numerous examples of functional shifts. In one of them, a surgeon in his 50s suffers a stroke. His left arm is paralyzed. During his rehabilitation, his good arm and hand are immobilized, and he is set to cleaning tables. The task is at first impossible. Then slowly the bad arm remembers how to move. He learns to write again, to play tennis again: the functions of the brain areas killed in the stroke have transferred themselves to healthy regions!

 

The brain compensates for damage by reorganizing and forming new connections between intact neurons. In order to reconnect, the neurons need to be stimulated through activity.

 

Conclusion

No matter a person’s age, plasticity or change within a brain is possible through learning. Our brains are truly extraordinary; unlike computers, which are built to certain specifications and receive software updates periodically, our brains can actually receive hardware updates in addition to software updates. Different pathways form and fall dormant, are created and are discarded, according to our experiences.

 

When we learn something new, we create new connections between our neurons. We rewire our brains to adapt to new circumstances. This happens on a daily basis, but it’s also something that we can encourage and stimulate.

 

References:

Theconversation.com

Sharpbrains.com – (Brain plasticity – how learning changes your brain. Dr Pascale Michelon & Can you grow your Hippocampus? Dr Majid Fotuhi)

www.understood.org