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The Human Brain
Welcome to your super fast introduction to functions of the brain! Eh, Wait a Minute - Take Me Back to the Previous Page!
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The brain is made up of two hemispheres - you can see one hemisphere in the picture above.
Each hemisphere of the brain has dominant control over the opposite side of the body, e.g.
the right hemisphere is usually responsible for movement of the left arm. Information from
the eyes is also crossed over - each eye has access to a left and a right visual field
(left and right sides of the retinas at the back of the eyes);
information from the left visual fields is sent to the right visual cortex, information from the
right visual fields to the left visual cortex. The visual cortex is the area at the back of the
brain which interprets the pattern of electrical activity from the nerves attached to the retina, the optic nerves.
To some extent then, there is a symmetry between
the two hemispheres, i.e. they perform the same functions, albeit for opposite sides of the body,
but each hemispheres also specialises
in certain tasks. In most people, the
left hemisphere dominates in speaking and writing skills, while the right hemisphere has
superior spatial skills, for example, map reading. We can deduce these facts through the study of patients who have undergone brain injury; people with left hemisphere damage often suffer from speech difficulties, those with right hemisphere damage may find that they are unable to find their way around as easily as before due to a loss of spatial skills. The speaking hemisphere is regarded as the
dominant hemisphere,
the non-speaking as the minor hemisphere.