The human brain is so extraordinary. At one time it was thought that after a certain age, our brains developed no more; brain cells died off and were not replaced. This was the conclusion reached by the 1906 Nobel Prize winner Santiago Ramón y Cajal and published in his 1913 book, Degeneration and Regeneration of the Nervous System. Fortunately in 1998 a new type of cell was discovered by Frederick Gage and Peter Eriksson – a neuronal stem cell. These divide and differentiate to become neurons or glial cells which support neurons in the brain. Stem cells in this case are baby brain cells and it is these that keep the brain rejuvenating – and this process goes on until the day we die.
The video above of the blind man seeing is as a result of the work of the polymath scientist Paul Bach-y-Rita. This discovery of the plasticity of the brain, of its ability to change according to need was inspired by the massive stroke his father suffered at the age of 65. The stroke paralysed his face, half his body and left him unable to speak. Officially there was no hope of recovery and it was recommended he be put into an institute. Instead Paul’s brother, George, took it on himself to rehabilitate his father by first teaching him to crawl, to catch marbles, to pick up coins from the floor with his paralysed hand, to do the washing up and slowly, over the course of a year, the father, Pedro Bach-y-Rita, made a full enough recovery to return to work full time, teaching at City College in New York. When Pedro finally died, a full autopsy was performed and it was found that his stroke had caused a massive lesion mainly in the brain stem. 97% of the nerves that run from the cerebral cortex to the spine were destroyed and this had caused his paralysis. It wasn’t that the lesion healed – it was his brain that changed to overcome the lesion and enabled Pedro to resume normal life.
And so Paul started working with stroke patients and in the course of this found that tactile images that enter the brain through the tongue are processed by the visual cortex1. Now there is a whole science of sensory substitution enabling the blind to see, those with severe balance problems to regain normality to their lives, those who have lost the sense of touch can have it restored – all this using the ability of our brain to adapt and change.
So the message for us fortunate to have all our senses is the familiar use it or lose it. If we stop doing something, then that part of the brain will be used to do something else instead. And if we reduce our lives on the feeble excuse of getting older, then we reduce the capacity of our brain. Pablo Casals, the great cellist, was asked by a student, ‘Master, why do you continue to practice?’ – Casals was 91 at the time – and he replied ‘Because I am making progress’.
For more information I refer you to the book The Brain that Changes Itself by Norman Doidge.
- Bach-y-Rita P, Kercel SW. Sensory substitution and the human-machine interface. Trends in Cognitive Sciences Vol 7 No 12 Dec 2003 [↩]