The Cerebral Cortex

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The Cerebral Cortex

  1. 1. The cerebral cortex is the part of the brain that  is visible from the outside. The cerebral cortex is the outermost layer of the brain and consists of a collection of nerve cell bodies made up of gray matter. The axons of these neurons extend in toward the center of the brain and into the white matter.
  2. 2. The brain is divided into two hemispheres,  each of which has slightly different functions. The neurons in one hemisphere communicate with neurons in the other hemisphere primarily across a bundle of nerves uniting the two hemispheres and known as the corpus callosum.
  3. 3. In humans, the cerebral cortex is larger than in other animals and has more folds than the cerebral cortexes of other animals. Comparison of the cerebral cortexes of different mammals.
  4. 4. The cerebral cortex is made up of layers (called  laminae) and columns of cells that are perpendicular to the laminae. The laminae vary in thickness from one area of the cortex to another, and specific columns are involved in very precise activities (for example, responding to a specific pattern of light or a specific kind of touch). For example, when you pick up a pencil to write something, the touch sensation of the pencil on the palm of your hand is in response to a specific column in the cerebral cortex.
  5. 5. The cerebral cortex is also divided into five  distinct areas called lobes. Each lobe has a specific set of responsibilities. The occipital lobe is at the very back of the  brain. It is most important for seeing, and contains an area called the primary visual cortex. People can become blind because of damage to the occipital lobe of the brain, even if there is nothing wrong with their eyes.
  6. 6. The parietal lobe is located right above the  occipital lobe of the brain. The parietal lobe has to do with touch sensations and other body sensations including location of the body in space. For example, if you are looking at something (and this would involve the occipital lobe), the parietal lobe would give you information about which direction your eyes are pointing, the position of your head, and the tilt of your body as you viewed the object.
  7. 7. The temporal lobe is on each side of your brain (in  the areas near your temples). The temporal lobe of the left side of the brain is important for understanding spoken language for most people. The temporal lobe also has some jobs related to vision, such as being aware of movement and recognizing faces. One of the main jobs of the temporal lobe is hearing in general, and it also plays a role in certain emotions and enthusiasm for certain activities.
  8. 8. The frontal lobe is in the front part of the brain. The  frontal lobe is important for planning movements and also contains the primary motor cortex, responsible for control of certain movements, such as moving one finger at a time. The frontal lobe helps with certain kinds of decision making that may have to do with control of behaviors in certain situations. For example, if a phone rings, you would answer it in your own home but probably not in a friend’s home. If you saw a friend at a distance, you would probably call their name to get their attention if you were in a mall but not if you were in the library. So the frontal lobe helps control our impulses so we don’t behave in inappropriate ways.
  9. 9. The four lobes of the human brain.
  10. 10. While the four lobes of the brain all have different jobs  to do, they also all have to work together. For example, if you bite into an apple, you see it’s color, its shape, experience how it smells, and know whether it tastes sweet or tart. How all areas of the brain provide this information is called the binding problem. There is no location in the brain where all of the various lobes send their information so they can be combined.
  11. 11. How you experience all these different ways of  knowing about the apple at the same time is still somewhat of a mystery, but most researchers think various brain areas that give us different information about the apple (the way it looks, how it smells, and how it tastes) have neurons that are all firing at the same time. Even though neurons are firing in different parts of the brain, because they are all doing so at the same time, our impression is of a single object or event, and not multiple parts of an object or event that are separate from each other.

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