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
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
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.
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.
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.
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 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
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.
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.
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.