Question: How do the cells in different parts of the brain change as you grow up and how do cells in the brain fix themselves?

Dawn Lau answered on 20 Jun 2016:

Neurons (nerve cells in your brain) undergo a lot of changes during brain development, before you’re born. Neurons start off as stem cells, which receive special signals from certain parts of the brain that tell the stem cells to develop into a different type of cell. These signals are different according to different regions of the brain, which is why you end up with specialised cells in different regions and layers and a very complex brain.

Once you’re born, the brain continues to develop for about two years, but the number of neurons is mostly fixed by that time! The other cells in your brain, the non-neuronal cells called glia, continue to grow. Throughout your life, though neurons communicate with each other via regions called synapses on their processes. These synapses are continuously removed, and added, or their shape might change, throughout your entire life. For example, if you learn to play the piano, you will form new synapses as you learn this new skill. If you stop playing for a long time, these synapses will disappear eventually. This process called synaptic plasticity happens throughout life.

Cells in the central nervous system, including brain cells, can’t repair themselves as easily as the peripheral nervous system. When you get an injury to your brain, the glial (non-neuronal) cells come swarming to the rescue to stop the injury from spreading, but this forms a glial scar and actually prevents further repair from happening. It’s a very strange phenomenon, and neuronal repair is a hot topic in neuroscience at the moment so watch this space, maybe there will be an update in the future!