The Structure and Function of the Cerebrum - Each half of the cerebrum consists of an internal mass of white matter and a thin, outer covering of grey matter, called the cerebral cortex. Compared to a falcon with its keen eyesight or a dog with its sense of smell, humans lack many sensory capabilities. Due to the evolution of the cerebral cortex, however, humans are considered to have the most sophisticated intellect and behaviour of all animals.
The cerebral cortex is responsible for language, memory, personality, vision, conscious thought, and other activities that are associated with thinking and feeling. The cerebral cortex is about 5 mm thick and, as shown in Figure 11.27, is highly convoluted. This allows it to fi t a high concentration of grey matter within the confi nes of the skull. Relative to a smooth surface, the convolutions and fi ssures greatly increase the surface area, so that the cerebral cortex covers about 0.5 m2, or about the area of an open newspaper.
The right and left halves of the cerebrum are called the cerebral hemispheres. They are linked by a bundle of white matter called the corpus callosum. The corpus callosum sends messages from one cerebral hemisphere to the other, telling each half of the brain what the other half is doing. Surgical isolation of the hemispheres is sometimes used to treat epilepsy, a condition that causes uncontrollable seizures. Scientists think that epilepsy can be caused by an overload of neurological electrical activities, so the corpus callosum is cut to prevent the spread of the epileptic seizures from one hemisphere to the other.
Research indicates that, while every cognitive function contains right-brain and left-brain components, some functions seem to have a dominant hemisphere. In general, the right-brain, or right cerebral hemisphere, is associated with holistic and intuitive thinking, visual-spatial skills, and artistic abilities. The left-brain, or left cerebral hemisphere, is linked to segmental, sequential, and logical ways of thinking, and to linguistic and mathematical skills. This is why people who are right-brain dominant process and learn information differently from people who are left-brain dominant. One way to illustrate the difference between right-brain and left-brain processing is the Stroop effect. rather than the words themselves. This is diffi cult because, as one theory suggests, one side of the brain may dominate in word recognition, while the other side may dominate in colour recognition. In other words, this leads to a right-left brain confl ict!
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