1. Brain Plasticity

2. To what extent can a damaged brain reorganize itself?
Brain plasticity: brain’s ability to change, esp. during childhood, by reorganizing after damage or by building new pathways based on experience.
*i.e.: constraint induced therapy: aims to rewire brains by restraining a fully functioning limb & forcing use of the “bad hand”…gradually reprograms the brain, improving the use of a brain-damaged child or adult stroke victim. {The damaged brain functions migrate to other brain regions.} –stroke victim cleaning tables w/ good arm & hand restrained…bad arm recovers its normal skills.

3. Other examples of plasticity:
*Blind person uses one finger to read Braille, brain area dedicated to that finger expands as the sense of touch invades the visual cortex
* Deaf person who use sign language, the temporal lobe area dedicated to hearing waits eagerly for stimulation…it then looks for other signals to process, such as those from the visual Sx…enhanced peripheral vision.
*Lose a finger & the sensory cortex that received its input will begin to receive input from adjacent fingers, which then become more sensitive
*Phantom Limb Phenomenon: hand amputated, but stroking the arm of the person, they report feeling sensations not only on arm but also on the “phantom limb” b/c sensory fibers that terminate on adjacent areas had invaded the brain area vacated by the hand.

4. Neurogenesis Humans are able to generate new brain cells.
“baby” neurons originate deep in the brain & may then migrate & form connections with neighboring neurons.
Implications for stem cells & stem cell research
Natural promoters of neurogenesis: exercise, sleep & nonstressful but stimulating environments.

5. Hemispherectomy
An entire hemisphere is removed (seizures) but the remaining hemisphere can take over the functions of the one removed.
The younger the patient, the better the recovery in terms of plasticity & neurogenesis.
Able to retain memory, personality, intelligence & humor.