The Brain: Damage Response and Brain Hemispheres 1.4c

Responses to Damage:

• Brain functions are assigned to specific areas and functions

  • one who suffered damage to the temporal lobe area (responsible for facial recognition) was never able to recognize faces

• some neural tissue can reorganize in response to damage

• after serious damage, an undamaged hemisphere will create extra connections to substitute

• neuroplasticity works well for people with blindness or deafness

  • it makes unused brain areas available for other uses

• similarly, reassignment may occur when disease frees up other brain areas normally dedicated to specific functions

  • if a slow growing left hemisphere tumor disrupts language, the right hemisphere will compensate

• Neurogenesis: producing new neurons

• Stem Cells: can develop into any type of brain cell

The Divided Brain

• Lateralization becomes apparent after brain damage

• left-hemisphere accidents can impair reading, writing, speaking, arithmetic reasoning, and understanding

• Corpus Callosum: the wide band of axon fibers connecting the 2 hemispheres and carrying messages between them

  • researchers speculated seizures were caused by abnormal brain activity bouncing back and forth in the 2 cerebral hemispheres. So they severed patients’ corpus callosum (split-brain surgery), and the results were that their seizures stopped

• Each eye receives sensory info from the entire visual field. But in each eye, info from the left hemisphere (controls speech) of your field of vision goes to your right hemisphere and vice versa

• Split-brain surgery leaves people with 2 separate minds

  • the left hemisphere tries to rationalize reactions it does not understand

• with split-brain surgery, both hemispheres can comprehend and follow instructions to copy simultaneously different figures with the left and right hand

Right-Left Differences in the Intact Brain

• when a person performs an interpretive task, there is increased activity in the right hemisphere

• when a person speaks or does math, activity is increased in the left hemisphere

• the right hemisphere excels at making inferences, helps us modulate speech (instead of “Let’s eat Grandpa!” it’s “Let’s eat, Grandpa!”), helps orchestrate our self awareness