How Does the Brain Repair Itself?
Plasticity refers to the capacity of the nervous system, particularly the brain, to modify and change. Whether or not a person can recover from brain damage depends on two factors - the age of the individual, and the extent of damage in the brain. For instance, damage to the left hemisphere of the cerebral cortex after 5 years of age leads to permanent disruption of language ability. This means that damage to certain parts of the brain can only be recovered at certain periods in an individual's life.
The Natural Way of Recovering from Brain Damage
The brain repairs itself naturally in three ways - collateral sprouting, substitution of function, and neurogenesis.
- Collateral Sprouting happens when axons grow new branches to compensate with adjacent damaged and non-functioning neurons. Picture a spider fixing a hole in its web.
- Substitution of Function happens when the function of the damaged area is taken over by another area in the brain. Brandi Binder's right hemisphere was removed when she was 6 years old to prevent epileptic seizures from occurring. Although she was not able to regain the use of her left arm, her left hemisphere gradually took over the functions of the right hemisphere in controlling the left side of her body. (Note: The right side of the brain controls the left side of the body, and vice versa. In Brandi Binder's case, the left side of her brain almost completely took over the control of both sides of her body.
- Neurogenesis happens when new neurons are generated in the brain. Although it is widely believed among neuroscientists that the brain already contains all the potential neurons at birth, Gould and others (1999) documented thousands of new growing neurons in monkeys. As more research about this phenomenon is being conducted, hastening neurogenesis in humans might as well be the cure for degenerative brain disorders such as Parkinson's and Alzheimer's Diseases.
The Artificial Way of Repairing Brain Damage
Brain Damage may be repaired artificially by means of Brain Grafts. Brain tissues, especially those coming from fetuses, are implanted to damaged areas for fresh neurons to connect with neighboring functioning neurons. On patients with Parkinson's Disease, brain grafts decrease the negative symptoms of involuntary tremors for those 60 years old and below. Motor and cognitive skills improve on stroke patients. Renowned actress Patricia Neal, for example, got stroke when she was 39 years old. Her leg was paralyzed and she was unable to read, write and speak. Yet after 4 years of intensive rehabilitation program, she was able to resume her acting career. Brain grafts also pose potential treatment for Alzheimer's Disease. For instance, it was observed that neuronal degeneration among rats with this disease reverse as a result of brain tissue implants. However, this phenomenon has not yet been observed among humans.