Neuroscience: What is Brain Plasticity?

Neuroscience has changed considerably in the past 20 years. An example of change over period is the concept of brain plasticity. Brain plasticity refers to the brain's ability to rewire itself, relocating information processing functions to different brain areas and/or neural networks. Two decades ago, it was believed that brain networks were static after its initial formation period. Now that belief has changed. The study of brain plasticity has profound implications in human learning and behaviour, and as such, for mental health.

To better understand this concept, let's take a quick tour of the human brain, neural networks, and the plastic potential therein.

Brains, Neurons and Networks

The brain is a multilayered parallel structure in which billions of neurons are interconnected and exchange information through neural networks. In the brain, each neuron is connected to thousands of other neurons through synapses (specialised neuronal junctions). A connected neuron receives input from several other neurons, and when the input weight reaches a threshold value, the neuron propagates an electrical signal that stimulates output through the ignition of a neurotransmitter (input to another neuron).

This electrochemical exchange is the basis of brain cell communication. It is also the premise for the formation of neural networks. These networks are formed during early childhood and are responsible for particular brain tasks, such as learning, pattern recognition and problem-solving. It was believed that once neural networks were formed, they would remain 'hard-wired' or inflexible. However, research in the past two decades has indicated that this is not the reality: our neural networks are in fact adaptive, flexible and responsive to change.

Rewiring is the Key

So what does it really mean to have a plastic brain? It has many implications to human behaviour and learning patterns. Primarily, it defies the old adage that "an old dog cannot learn new tricks". It is clear that with age, it becomes increasingly more difficult to learn new things. However, the brain's ability to adapt to change perpetuates throughout an individual's lifetime.

A prominent case of neuroplasticity happened with a patient who spent 19 years in a coma. Terry Wallis, a 19 year old man from Massachusetts (US), woke up after spending 19 years in a minimally conscious state. When scientists scanned his brain combining PET (Positron Emission Tomography) and DTI (Diffusion Tensor Imaging) technologies, they found evidence that Wallis's brain had "developed new pathways and completely novel anatomical structures to re-establish functional connections, compensating for the brain pathways lost in the accident" (New Scientist, 03/07/2006).

Other cases, including stroke victims, people who have lost sensorial abilities (e.g. visually impaired) and individuals who have suffered cortical injuries show similar conclusions after researchers have investigated how they have recovered, or how the brain rewired itself to compensate for the damaged areas and lost functions. The process of rewiring occurs when new connections (synapses) between neurons are formed and, if they prove to be favourable, they are likely to become more permanent and stabilised. This process allows the brain circuitry to be malleable to changes, or in other words, to form 'uncommon' networks under particular conditions.

Learning and Plasticity

Brain plasticity is not restricted to unplanned circumstances, such as accidents, brain traumas and other critical instances that require rewiring to re-establish functional connections. Learning is also a major beneficiary of brain plasticity. Studies with musicians and athletes have shown that particular areas of the brain responsible for 'fine' or 'specific' movements in certain parts of the body (e.g. the hands of a pianist or string musician) are in fact rewired for optimization. Once training becomes a routine, and particular movements are repeated over and over again, the tendency is that neuronal connections will become more permanent.

But there is more to it. Physical contact is not a requirement when it comes to rewiring. Repeated thinking can also trigger a series of reactions which result in brain rewiring. Scientists have investigated the formation of synapses as a result of 'thinking about doing something' and found that, from a neuronal perspective, thinking can be as useful as doing. This evidence led to an interesting fusion of interests between Buddhist meditation (through the Dalai Lama's interest on the influence of the mind over the brain) and the scientific research on brain plasticity and the formation of neural networks. It seems that brain plasticity is a flexible topic as well as a flexible concept.

Mind Your Thoughts

Learning and plasticity took centre stage when collaborative research was conducted with lamas (Buddhist equivalent for priests or spiritual leaders). It seems that, as a result of ongoing meditation through a technique called Mindfulness (which aims to improve the person's control and awareness of thoughts and emotions), the lamas were 'more able' to attain emotional balance and to concentrate.

Some of these studies include experiments performed by Dr. Kabat-Zinn (who taught mindfulness to workers in a high-pressure biotech business and concluded that stress levels were optimized over a short period of time) and Dr. Ekman's tests involving emotional expression detections. "The mindfulness training focuses on learning to monitor the continuing sensations and thoughts more closely, both in sitting meditation and in activities like yoga exercises" (NY Times, 04/02/2003).

The benefits of meditation through brain rewiring, from a non-religious perspective, are becoming clearer and quite appealing. Currently, there are therapeutic techniques that mix mindfulness with other mainstream therapies such as Cognitive Behaviour Therapy. These have proven particularly useful for cases of depression and anxiety, for example.

Stepping Into the Unknown

Brain plasticity has become a major topic of study. As modern scanning technologies enable scientists to observe the formation of synapses under particular stimuli, and experiment with living organisms, the applications of this knowledge are reaching a range of research fields. Some scientists have promoted the idea of using stimulation to improve learning, however, at a neurochemical level. Others like the idea of meditation and 'wishful thinking' to empower the process of learning and to optimize the performance of certain tasks.

This collaborative approach from representatives of a non-dogmatic religion such as Buddhism, cognitive researchers and neuroscientists seems to be opening an attractive scope on the concept of brain plasticity. How far will this go? Hard to say, but nevertheless: very interesting to mind.

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