Brain HemisphereOrganization

The Thinking Part of the Brain: Components of the Cerebrum

• Cerebral Hemispheres– left and right halves of cerebrum

• Corpus Callosum– connects the two hemispheres

• Cerebral Cortex– thin outer covering of cerebrum– responsible for higher mental processes

of language, memory, and thinking

The Thinking Part of the Brain: Components of the Cerebrum

• The cerebral cortex contains 3 types of areas. – Sensory Input Areas

• vision, hearing, touch, pressure, and temperature register

– Motor Areas• control voluntary movement

– Association Areas • Higher mental functions such as memory,

thought, learning, perception, and language

The Thinking Part of the Brain: Components of the Cerebrum

• Lateralization – the specialization of one of the cerebral

hemispheres to handle a particular function

• Left Hemisphere– controls the right side of the body– handles most language functions– specialized for mathematics and logic

The Thinking Part of the Brain: Components of the Cerebrum

• Right Hemisphere– controls left side of body– Excels in making inferences

• foot, cry, glass = • Boot, summer, ground =

– interprets emotional messages conveyed by tone of voice and gestures

• What’s in the road ahead?

– is specialized for visual-spatial relations

The Thinking Part of the Brain: Components of the Cerebrum

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Lateralized Functions of the BrainAssigning functions to one hemisphere or the other

allows the brain to function more efficiently.

When the Brain is Split

• Corpus callosum is absent or has been surgically modified.

• Only the verbal left hemisphere can report what it sees.

• The left hemisphere does not see what is flashed to the right hemisphere; the right hemisphere is unable to report verbally what it has viewed.

In an experiment, a visual image (an orange) is flashed on the right side of the screen, it is transmitted to the left (talking) hemisphere. When asked what he sees, the split-brain patient replies, “I see an orange.”

Testing a Split-Brain Person

When an image (an apple) is flashed on the left side of the screen, it is transmitted only to the right (nonverbal) hemisphere. Because the split-brain patient’s left (language) hemisphere did not receive the image, he replies, “I see nothing.”

But he can pick out the apple by touch if he uses his left hand, proving that the right hemisphere “saw” the apple.

Testing a Split-Brain Person

Split Brain Experiments

The Divided Brain

Right-Left Differences in the Intact Brain

• Hemispheric Specialization–Perceptual tasks–Language–Sense of self

• Handedness

Pat Venditte