The short answer is Neuroplasticity (commonly called 'brain plasticity') is a term referring to all sorts of neural changes, for example the production of new neurons, reshaping neurons, and changing the way they communicate with each other. It is very important because without it we cannot learn new things, we cannot grow new neurons, and we cannot regain lost functions (for example due to stroke) and many other ‘cannots'.
The longer answer requires an understanding of the concept of Neurogenesis - the production of new neurons - changes in a single neuron, and changes in networks of neurons.
https://www.youtube.com/embed/9D1AwQ0lTsg?wmode=opaque
Neurogenesis - the brain repairing itself
Before we dive into the brain though, let me begin with a question. Imagine you are riding a bike, you fall off and you scratch your skin. What happens to the skin afterwards? It repairs itself by growing new skin, right? So, skin has the capacity to regrow. The same applies to neurons.
You can increase neurogenesis to help the brain to repair itself, just like your skin. You can do so by regular physical exercise. It doesn’t need to be rigorous – walking is often sufficient.
A few years ago scientists thought that brain grows new neurons only until a certain age and it begins losing them after that. Recent discoveries, however, have proven that the earlier thinking was wrong: the brain keeps on generating new neurons, but with different rates throughout life and in some brain areas more than others. For example, a part of the hippocampus (called dentate gyrus) keeps on producing new neurons all the time and at all ages. This area is thought to have a critical role in the formation of new episodic memories (memories of past personal experiences) and some other functions. Considering that neurons die continuously, losing the ability of producing new neurons to replace them leads to all sorts of memory difficulties. You can increase neurogenesis to help the brain to repair itself, just like your skin. You can do so by regular physical exercise. It doesn’t need to be rigorous – walking is often sufficient.
To understand how changes in a single neuron work, let's consider how neuroplasticity contributes to the formation of new memories. Amongst many ways that memories are stored in the brain, neuroplasticity and synaptic plasticity are two of the most important mechanisms. Both refer to the way that neurons excite or inhibit each other. Neurons are not physically touching each other, but they communicate via electrical or chemical signals through a structure that is called the synapse. Synaptic plasticity refers to changes in this structure that leads to the way that two neurons communicate with each other, for example one can excite the other neuron more or less strongly. In synaptic plasticity the actual structure of the neuron is fixed, but the communicating channels, axons (transmitting terminals) and dendrites (receiving terminals), change. In addition to these changes, neurons can grow new communication channels (axons or dendrites) - another facet of neuroplasticity.
https://www.youtube.com/embed/2MKNsI5CWoU?wmode=opaque
Changes in a network of neurons
On a larger scale, neuroplasticity refers to changes in the function of neurons within a network of neurons. Let me ask you another question. What is the difference between people who are extremely good in maths and those who are extremely good in languages? Part of the difference lies in the way their brain allocates brain areas to different tasks – those with better maths abilities devote a larger brain area to the maths process, and those with language abilities devote a larger brain to language processes. These people are not necessarily born with a larger brain area for this or that task. It's a scientific fact that you can restructure your brain by training it. It is a slow process, and requires a lot of training, but you can do it.
Let me ask you another question. What happens to the brain areas responsible for vision in blind people? Basically the brain uses those areas for other tasks, for example they are better with other senses such as their sense of touch. Similar thing happens with a stroke. When the patient loses some part of their brain, other parts of their brain restructure to compensate for the functionality of the lost parts.
So, there are many ways that neuroplasticity contributes in everyday life, which makes it an extremely important property of neurons and the nervous system in general.
Learn more about Dr Javadi's work in Neuroscience at his website here.