Whaaat? It was largely accepted until fairly recently that the human adult brain, was essentially fixed. This was illustrated in full color diagrams confidently mapping the regions and structures responsible for say moving the left pinkie or for processing the feelings of biting the tongue. Ouch! It was believed that every bit of neural real estate was zoned and assigned a specific function. So, it had to be true, right?
Wrong! Much research in recent decades has proven this to just not be the case. Many scientific studies have confirmed that the brain is plastic meaning it is not fixed, not static, and not hard wired. It is malleable, dynamic and capable of physical change all throughout adulthood.
I like to think of our brain like play dough. We are holding this blob in our hands and can shape it however we choose. We sculpt our brain with our environment, our experiences, the demands we place on it repeatedly, and, basically, the lives we lead every day. Works both ways - good and bad.
Plasticity was demonstrated early on in an experiment with ferrets, who have identical wiring to the auditory cortex and visual cortex as humans except for one important factor, the timing. Human basic wiring exists at birth. Ferrets grow this circuit after birth. Scientist interrupted this pathway in the ferrets with some very careful brain surgery so that nerves from the eye grew into the auditory cortex. The ferrets were then trained to respond to sounds and lights. The ferrets "heard" the lights with parts of the brain that would normally process sound.
In a later experiment, sighted adults were blindfolded all day, every day for 5 days. They spent their time learning Braille and performing various tactile and auditory activities. Their brains were scanned before and at the end of the experiment. Beforehand, their auditory cortex showed normal activity upon hearing sound. Their visual cortex lit up when seeing as expected, and their somatosensory cortex buzzed appropriately when fingering Braille symbols.
After just 5 days of being blind folded, their "visual" cortex became active when doing all these things. The "seeing" brain was now hearing and feeling. Even though it had spent all its years up until that point handling visual input, with no signals coming from the eyes at all, the brain reorganized itself to utilize the newly dormant areas for other functions - sort of like an industrious developer seizing some prime vacant piece of land and capitalizing on it.
This same amazing ability is the cause of phantom limb. People who have lost a limb experience a brain reorganization. The part of the brain that formerly received input from the missing limb is taken over by neighbors on the homunculus. Because the face and the hand are side by side, it has been documented that someone missing a hand actually learned where to scratch on their face to satisfy an itch on the missing hand.
Phantom pain has been shown to be caused in most cases by that being the last signal the brain received from the lost limb. In a confused loop, the brain processes this sensation endlessly. This phenomenon has miraculously been alleviated by utilizing neuroplasticity and tricking the brain and interrupting this cycle with mirrors which visually replace the lost limb and change the signals to the brain.
There is a catch to neuroplasticity. It only occurs when a person is paying attention and focusing on the input whether it be intentional or not. Hence with directed consciousness, a person has the ability to change their brain. Unfortunately, this is more often done unconsciously by most people.
The science of neuroplasticity is very new. It's limits are unknown. It opens up a world of possibilities. In a very personal sense, each individual has the power to change their life. On a broader scale, the same brains that now practice prejudice, hatred and warfare have the potential to be kinder, more compassionate and less aggressive. It can happen one brain at a time.