Plasticity is quite simply described as the brain's ability to adapt. Plasticity is integral in learning and memory, but more interestingly can be used to recover from severe injuries to the brain. I did some research into the recovery of Gabriel Giffords. For those who don't know, Gabriel Giffords is a US Representative from the state of Arizona. On January 8th 2011 Giffords was the victim of an assassination attempt. She was shot in the back of the head, the bullet passed all the way through her skull from back to front, but only in her left hemisphere. As we learned in class the left hemisphere controls the right half of the body. It is also responsible for things like logical thinking and speech.
Immediately after the shooting, Giffords was unable to speak, but could still respond to simple questions with hand gestures. She also was completely unable to walk or use the right side of her body at all. Over time though, and with great effort, her brain began to rewire itself. Through intense physical therapy she has relearned to walk and can now speak, though often not in complete sentences.
This is a true testament to the power of the brain. We learned in class that the brain truly is wired in a certain way from birth. Brain scans can show the exact location being used by our brains for particular functions like speech. However as we can see in examples like this one, that the brain can adapt from even serious injuries to these sections.