Functions of Specific Cortical Areas

Studies in human beings by neurosurgeons, neurologists, and neuropathologists have shown that different cerebral cortical areas have separate functions. Figure 57-3 is a map of some of these functions as determined by Penfield and Rasmussen from electrical stimulation of the cortex in awake patients or during neurological examination of patients after portions of the cortex had been removed. The electrically stimulated patients told their thoughts evoked by the stimulation, and sometimes they experienced movements. Occasionally they spontaneously emitted a sound or even a word or gave some other evidence of the stimulation.

Supplemental and premotor

Primary somatic Primary motor

Secondary somatic

Supplemental and premotor

Primary somatic Primary motor

Parieto-occipito-temporal Association Area

Limbic Association Area

Primary Secondary auditory auditory

Figure 57-4

Secondary visual

Limbic Association Area

Parieto-occipito-temporal Association Area w

Primary visual

Primary Secondary auditory auditory

Figure 57-4

Locations of major association areas of the cerebral cortex, as well as primary and secondary motor and sensory areas.

Putting large amounts of information together from many different sources gives a more general map, as shown in Figure 57-4. This figure shows the major primary and secondary premotor and supplementary motor areas of the cortex as well as the major primary and secondary sensory areas for somatic sensation, vision, and hearing, all of which are discussed in earlier chapters. The primary motor areas have direct connections with specific muscles for causing discrete muscle movements. The primary sensory areas detect specific sensations—visual, auditory, or somatic— transmitted directly to the brain from peripheral sensory organs.

The secondary areas make sense out of the signals in the primary areas. For instance, the supplementary and premotor areas function along with the primary motor cortex and basal ganglia to provide "patterns" of motor activity. On the sensory side, the secondary sensory areas, located within a few centimeters of the primary areas, begin to analyze the meanings of the specific sensory signals, such as (1) interpretation of the shape or texture of an object in one's hand; (2) interpretation of color, light intensity, directions of lines and angles, and other aspects of vision; and (3) interpretations of the meanings of sound tones and sequence of tones in the auditory signals.

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Essentials of Human Physiology

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  • KERSTIN
    Which are the specific cortical areas?
    2 years ago

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