The brain is not only an extraordinary system, but also immensely flexible and adaptable.  The way in which cells in the brain and other parts of the nervous system can adapt to change serves important functions in the brain, such as learning, the forming and retrieving of memory, or responding to brain damage.  The amazing ability of the brain to change and adapt to new experiences – by creating new connections between brain cells (neurons) – is referred to as brain plasticity, also known as neuroplasticity.  In neuroscience, plasticity refers to adaptability.

Electrochemical activity in the brain:

neurons firing

The brain is thought to contain more than 100 billion nerve cells (neurons), interconnected by over a trillion synapses. which is the point of contact, or connection, between neurons.  Sensory input (from our environment) to the brain is sent via electrochemical signals between neurons to different parts of the brain.  These complex electrochemical signals form the basis of the brain’s essential functions, such as forming memories and thoughts, initiating actions, as well as assisting to interpret the world around us.  Neurons are the basic building blocks of the body’s nervous system.

Neurons communicate with each other via electrochemical signals.  The electric events that take place across the synapses (connections) between neurons are called action potentials.The chemical part of this communication process starts when an action potential reaches the synaptic cleft (“gap”) between neurons and causes neurotransmitters (” chemical substances”) to be released from the neuron’s axon into the cleft.  After crossing the cleft, the neurotransmitters attach to receptors on the dendrites of the receiving neuron.   The synapse can be seen as the junction between the message-sending axon of one neuron and the message-receiving dendrite of another neuron, where the electrochemical communication processes take place and signals are transmitted.

At birth, each neuron in the baby’s brain has about 2 500 synapses, which increase by the age of three to about 15 000 synapses (connections) per neuron as infants explore the world around them, obtaining knowledge and learning new skills.

http://epilepsyu.com/wp-content/uploads/2015/10/synapses.jpg

What is brain plasticity?

Brain plasticity, in a nutshell, means the ability of the brain to modify its connections.  In the field of neuroscience, brain plasticity (neuroplasticity) refers to the ability of the brain to re-wire itself and create new connections between neurons.  The plasticity of the brain enables us to learn new things and new skills, as well as changing and adapting to stimuli from the environment.  It also allows the brain to recover from strokes and other brain injuries.  Learning new things and new experiences cause neural pathways to make new connections and to strengthen existing pathways.  Neural plasticity occurs in the nervous systems of species ranging from insects to humans.

The more than 100 billion neurons in the brain, each with thousands of ever-changing synapses (connections), have been compared to a massive school of fish that can suddenly change direction as a single unit.

Whatever you remember from reading this article, results from the storing of new information by the formation of new connections between specific subsets of neurons.

Some characteristics of brain plasticity:

Brain plasticity explains much about the structure and functions of the brain:

  • Brain plasticity starts with the development of a new neuron, and then individual neurons develop new connections with other neurons.  This results in growing clusters of nerve cells.
  • Neurons that are frequently used tend to develop strong connections, while those that are rarely or never used eventually die – a process that is known as synaptic pruning. 
  • Brain plasticity is ongoing throughout life and can also occur because of damage to the brain, such as a stroke, where new pathways are formed to partly of fully compensate for brain damage. 
  • Functional plasticity refers to the ability of the brain to move functions from a damaged area of the brain to other undamaged areas.
  • Brain plasticity enables the brain to regrow nerve bundles that are broken through injury or surgery – much like a plant that regrows around lost parts.
  • Structural plasticity refers to the ability of the brain to change its actual structure because of learning, or new experiences, which involves the reshaping of individual neurons through new connections.
  • Genetics play an important role in the functioning of brain cells, as certain nerve cells in certain areas in the brain are genetically programmed for specific functionality, for example some nerve cells are programmed to become grammar modules that enables the brain to process language.
  • Genetics also result in the basic structure of the brain being established before birth and development of the brain after birth relies on a process called developmental plasticity – where processes involved in the developing brain lead to changes in neurons and synaptic connections, such as the migration of neurons through the developing brain or by making or losing synapses.
  • As certain areas of the brain are genetically responsible for certain actions, for example movement, language, or speech, such an area may not fully recover from damage, as other areas in the brain cannot fully take over the functions that were affected by damage.
  • The electrochemical activity taking place in the synapses that connect brain cells can become more efficient if it fires often along the same pathways.  This characteristic is described in the field of neuroscience as “cells that fire together wire together”.
  • Brain plasticity decreases with age, along with normal age-related cognitive decline.  However, even into old age, brain plasticity continues to play a role in the ability to learn new skills, or new activities, or even new languages.
  • The decline in brain plasticity in older people can be seen in the way they become more fixed in their ways, while younger people can adapt and learn more rapidly.
  • In the mature brain new neurons are formed in two areas only – the dentate gyrus of the hippocampus, which is involved with memory formation and emotions, – and the sub-ventricular zone of the lateral ventricle, where new neurons migrate to the olfactory bulb, which is involved in the processing of the sense of smell.  While the forming of new neurons is not regarded as brain plasticity, it may play a role, along with brain plasticity, in the way the brain recovers from injury and damage.
  • Brain plasticity provides the brain with one of its many unique features, namely that the brain never ceases to develop.
  • Brain plasticity unfortunately cannot help the brain to recover from devastating late stage brain diseases such as dementia, Alzheimer’s, or Parkinsons, due to the toxicity of these diseases that can overpower the brain’s capacity for self-repair.
  • Deep sleep helps to maintain brain plasticity.  During the day, synapses switch on in response to stimuli from the environment and stay excited at their peak activity, but during sleep the activities of synapses goes back to normal and relax for this restorative period.
  • Brain changes due to psychoactive substances such as drugs, or pathological conditions, can have detrimental effects on brain plasticity.
  • Brain plasticity has its limitations, for example not everyone fully recovers from a stroke, as younger people have a better chance of recovery, and the size of the damaged area also plays a role.
  • A study amongst several London taxi drivers (who have greater demands on memory) found an increase in the volume of an area in the brain that is involved in short-term memory and spatial navigation.

Conclusions

Brain plasticity can be defined as the ability of the Nervous System to change its activity in response to intrinsic or extrinsic stimuli by reorganizing its structure, functions or connections (P Mateos-Aparacio and A Rodriquez-Moreno 2019). 

The brain is not infinitely adaptable, as certain areas of the brain play specific critical roles, for example in movement, speech, cognition, and language.  Due to the genetic predisposition and specific functionality of brain cells in certain areas in the brain, other areas in the brain cannot fully take over the functions that were for instance affected by brain damage.

It is possible to improve brain plasticity by enriching your environment for example by learning a new language or learning to play a new musical instrument.  Creating art or travelling and exploring new places, even reading, offers opportunities for focussed attention and stimulating positive changes in the brain. 

Regular physical exercise is thought to increase neuroplasticity through the regulation of growth factors and glial activation in the brain.

Despite modern brain imaging equipment such as MRI scans, much is still unknown about the mechanisms underlying brain plasticity.  Scientists still only know some of the brain regions in which plasticity occurs and only some of the mechanisms that are involved in this process.  Much more research is needed if we wish to fully understand how the human brain works

References:

The impact of studying brain plasticity. P Mateos-Aparacio and A Rodriquez-Moreno; Front. Cell. Neurosci 2019

 How experience change brain plasticity.  Published online and updated 3 February 2021.  Verywell Mind.  (A resource for mental health topics.)  (www.verywellmind.com)

What is brain plasticity?  Published 23 March 2021.  Simply Psychology.  (www.simplypsychology.org)

MIT scientists discover fundamental role of brain plasticity.  Published 22 June 2018.  MIT News.  Massachusetts Institute of Technology.  (www.news.mit.edu)

The impact of studying brain plasticity.  Published 27 February 2019.  Frontiers in Cellular Neuroscience.  (www.frontiersin.org)

What is brain plasticity and why is it so important?  Published 4 April 2016.  The Conversation.  (www.theconversation.com)

Explainer: nature, nurture, and neuroplasticity.  Published 26 February 2013.  The Conversation.  (www.theconversation.com)

What happens in the brain when we sleep?  Published 6 August 2020.  Medical News Today.  (www.medicalnewstoday.com)

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