easily the most complex living structure known, controlling the body like a puppetmaster, tracking your heart rate and breathing to your emotions, libido, learning, and memory.
Neurons, or brain cells, start growing at a phenomenal speed of quarter-million per minute when the foetus is just about four weeks old in the womb. By the time we are born, billions of neurons have interacted to form trillions of connections with each other to regulate how you think and function.
And the brain keeps evolving throughout life. At birth, the brain contains 100 billion - roughly the number of stars in the Milky Way - cells, with the number remaining fixed for the rest of life. Despite that, you can teach an old brain new tricks.
The brain has a quicksilver ability to reorganise itself by forming new connections between neurons. It undergoes its biggest overhaul when you are a toddler starting out to perceive the world, followed by when you're a teenager. In the teens, the brain development is concentrated on the prefrontal cortex, the part of the brain responsible for planning and emotional control, which explains why teenage is a notoriously emotionally unstable period.
Changes in brain structures continue through life and are influenced by how you use it. Perhaps this is best illustrated by the Nature Neuroscience study that found the region of the brain associated with navigational ability and spatial memory (located in the back of the hippocampus, just above the brain stem) becomes enlarged in London cabbies. The longer they had been driving, the bigger was the change.
Plasticity can also be observed in the brains of bilinguals, with more than one study showing that learning a second language makes the left inferior parietal cortex larger in bilingual brains than in monolingual brains. This functional change in bilinguals offers protection against degenerative diseases, such as dementia, as you age.
Then, in case of brain injury, there is the brain's superhero-like ability to compensate for lost functions or optimise supportive functions. The textbook example is that of Michelle Mack, 41, who has lived her entire life with half a brain after a pre-birth stroke destroyed the left hemisphere of her brain that controls movement, language, logical thinking, analysis and accuracy.
Mack, however, led a near-normal life graduated from high school and got a job, much before her problem was diagnosed when she was 27. She speaks normally, has an uncanny knack for dates because the right side of her brain rewired itself to make up for the function that was likely lost during a pre-birth stroke. Experts believe that during her development, the right hemisphere either took over or developed some of the language abilities that it cost her in some of the skills that are normally mediated by the right side of the brain.
Extensive learning of abstract information can also trigger neural changes, showed images of the brains of German medical students three months before their medical exam and right after the exam, as compared to the brains of those who were not studying for the exam. Scans of the brains of these medical students showed changes in regions of the brain (parietal cortex and posterior hippocampus) involved in memory retrieval and learning.
Deciphering the working of the brain not only makes scientists understand what makes us tick, but also provides ways to prevent and cure degenerative brain diseases such as dementia and Alzheimer's. The message is pretty clear: how your brain controls vision, language, memory and function is progressively refined by how you much you use it, so keep it whirring the best you can.