Neuroplasticity: How the Brain Is Capable of Change
Neuroplasticity: How the Brain Is Capable of Change
Neuroplasticity – otherwise known as brain plasticity – is a term used to describe how our brain reorganizes itself by forming new neural connections throughout life. It occurs on a variety of levels, which could be cellular in nature (brain changes due to learning) or something more large scale like cortical remapping (brain changes in response to an injury). Neuroplasticity has been a game changer since it was first introduced because the brain was thought to be a physiologically static organ in the past. However, the arrival of neuroplasticity clearly indicates that the brain does actually change throughout life.
To illustrate this concept a little bit better, imagine the film of a camera. Now, think about the film in the camera as the representation of your brain. Next, imagine that you’re in a park and taking a picture of a flower. What happens when you take the picture is that the film in your camera is exposed to new information, which in this case if the image of the flower. Now, in order for the image to be retained, the film should react to light and “change” so it can record the image of the flower. In the same way, your brain does the same thing. In order for new information to be retained in memory, changes in the brain that represent the new knowledge should occur.
Another good illustration is making an impression on cookie dough. Let’s just say you have a template that would mark an image of a bird onto the dough. In order for the bird to appear on the dough, changes need to happen in the dough. This simply means that the shape of the dough is clearly changed as the image of the dough is pressed into the clay. In a similar fashion, the neural circuitry in our brain also needs to reorganize itself in response to experience or sensory simulation.
A Brief History
A proposal
Up until the 1970’s, the accepted idea about the nervous system was that it was fixed throughout adulthood. Not only that, it was believed to be fixed in terms of brain function, as well as the idea that it was impossible to develop new neurons after birth.
However, an Italian anatomist by the name of Michele Vicenzo Malacarne changed all that after he released results of an experiment he did with animals. In his study, he paired animals, but only extensively trained one of them for years. After that, he dissected the brains of both. What he found was that the cerebellums of the trained animals were larger. However, all of his studies were forgotten.
It was in 1890 when William James proposed an idea that the brain and its functions aren’t fixed throughout adulthood. This was published in The Principles of Psychology, but then again the idea was not entertained as well.
More research
In 1923, Karl Lashley conducted experiments on rhesus monkeys that really demonstrated changes in neuronal pathways. This led him to conclude that brain plasticity is in fact real. However, neuroscientists didn’t accept this idea.
It was in the 1960’s when more evidence about brain plasticity started emerging, even from notable scientists such as Paul Bach-y-Rita, Michael Merzenich, Jon Kaas, and others.
A breakthrough
Paul Bach-y-Rita invented a device in the 1960’s that allowed blind people to read, perceive shadows, and distinguish between close and distant objects. The machine he invented was dubbed as one of the finest and boldest applications of neuroplasticity. What happened in his study was that a patient was asked to sit in an electrically simulated char that also has a large camera behind it. What the camera did was that it scanned an area, then it sent electrical signals of an image to four hundred vibrating simulators on the chair against the skin of the patient. The six test subjects were able to recognize the photo of the supermodel Twiggy.
Paul Bach-y-Rita believed in sensory substitution, which meant that if one of the senses is damaged, the others can take over. He believed that the skin and its touch receptors can act as the retina. Now, in order for the brain to interpret the tactile information and convert it into visual information, it needs to learn something new and adapt to the new signals. Given that the brain was able to adapt, meant that it did indeed possess plasticity.
Other neuroplasticity studies
A neuroscientist by the name of Michael Merzenich also performed some experiments that proved plasticity is real. One of his most bold claims was that brain exercises can be as powerful as drugs when it came to treating severe neurological illnesses like schizophrenia. He believed that plasticity existed “from the cradle to the grave” and that enhancements when it comes to cognitive functioning – the way we learn, think, and perceive – are possible even in old age. His studies were inspired by the work performed by David Hubel and Torsten Wiesel on kittens.
In their experiment, Hubel and Torsten sewed one of the eyes of the kitten shut and proceeded to record cortical brain maps. What they found was that the portion of the brain associated with the shut eye did not stop functioning. In fact, it processed visual information from the open eye. This simply implied that neuroplasticity existed during the critical period.
In his own study, Merzenich argued that neuroplasticity can extend beyond the critical period. In his postdoctoral study with Clinton Woosley, they observed what happened in the brain when one peripheral nerve was cut and subsequently regenerated. The two of them micromapped the hand maps of the monkey brains before and after cutting a peripheral nerve and sewing the ends together. They expected one hand map to be jumbled, but instead, it was nearly normal. This simply meant that we are not born with a hardwired system and that the brain is capable of plasticity.
Facts about neuroplasticity
Our brain is comprised of about 100 billion neurons. Early scientists believed that neurogenesis – which is the creation of new neurons – stopped just right after birth. However, thanks to new explorations into the topic, the brain has shown to possess a remarkable capacity to reorganize pathways, crate new connections, and yes, create new neurons.
With that said, here are the key facts about neuroplasticity:
1. It varies with age. Although plasticity occurs throughout life, there are certain types of changes that are more predominant during a specific time in our lives.
2. It involves a range of processes. Neuroplasticity is an ongoing event throughout life, and it involves more than just neurons. In fact, glial and vascular cells are also take part in the process.
3. It happens for two different reasons. One of the reasons is through learning, experience, and memory formation. The other is a result of damage to the brain. The first reason pertains to the development of the brain in the early stages of life when we start to process sensory information and carries on until adulthood. The second reason is more of an adaptive mechanism to compensate for a lost function, or is a way for the brain to maximize any remaining functions in the event an injury occurs.
4. The environment plays an essential role in the process. The brain is shaped by characteristics that surround us in the environment we live in. Not only that, it is also shaped by the actions we take in this environment.
Types of neuroplasticity
- Functional plasticity
This refers to the ability of the brain to move functions from a damaged area to an undamaged one. This type of brain reorganization takes place by mechanisms like “axonal sprouting,” which is when undamaged axoms grow nerve endings to reconnect the neurons whose links were injured or severed. Undamaged axoms can also grow nerve endings and connect with other nerve cells that weren’t damaged to form a new neural pathway to accomplish a needed function.
For example, if one hemisphere of the brain gets damaged, the intact portion can take over the functions of the damaged area. The brain can compensate for the injury by reorganizing itself and making new connections between neurons that are intact. In order for reconnection to occur, the neurons need to be stimulated through activity.
- Structural plasticity
This refers to the ability of the brain to change its physical structure due to the effects of learning. In the past, it was believed that as a person aged, their brain networks became fixed. However, studies in the field of neuroscience have proven that not to be true.
According to Durbach, there are two types of modifications that occur in the brain when it comes to learning:
1. There is a change in the internal structure of the neurons. The most notable is in the area of synapses.
2. There is an increase in the number of synapses between neurons.
Applications of neuroplasticity
Treatment for brain damage
One of the most recent applications of neuroplasticity was the work done by the team of doctors and researchers at Emory University. The work they did was the first treatment that showed significant results in treating traumatic brain injuries in decades. They noticed that female mice recovered better after brain injuries, especially during the estrus cycle. So, the researchers injected progesterone to brain injured patients, and the shots actually reduced mortality by 60%.
Treatment of learning difficulties
A series of “plasticity-based computer programs” was developed by Michael Merzenich to treat dyslexia. The programs involved seven brain exercises designed to reverse the dysfunctions caused by age-related cognitive decline (ARCD) in cognition, memory, and motor control – just to name a few. After about 8-10 weeks of using the program, those in the study showed a significant increase in task-specific performance. It just goes to show that a neuroplasticity-based program can help in improving cognitive function and memory in adults with ARCD.
Human echolocation
Human echolocation refers to the learned ability of humans to sense their environment from echoes. This particular ability is used by blind people to navigate their environment and sense their surroundings in detail. Functional MRI techniques of studies conducted in 2010 and 2011 show that parts of the brain linked to visual processing adapts for echolocation. Basically, the click-echoes heard by blind patients were processed by the region of their brain devoted to vision rather than audition.
Conclusion
Neuroplasticity puts a new spin to the saying “You can’t teach an old dog new tricks.” Thanks to studies conducted and still being performed in the field, it’s confident to say that the adult brain is very much capable of learning new things even in the very later stages of life. This has also been evidenced by quite a number of people who have learned a new language even in old age. Even though it may take a while longer to learn new things, it’s comforting to know that plasticity can in fact come into play even as we mature.
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