The Cerebral Cortex Is Functionally Compartmentalized

In the human brain, the surface of the cerebral cortex is highly convoluted, with gyri (singular, gyrus) and sulci (singular, sulcus), which are akin to hills and valleys, respectively. Deep sulci are also called fissures. Two deep fissures form prominent landmarks on the surface of the cortex; the central sul-cus divides the frontal lobe from the parietal lobe, and the sylvian fissure divides the parietal lobe from the temporal lobe (Fig. 7.8). The occipital lobe has less prominent sulci separating it from the parietal and temporal lobes.

Topographically, the cerebral cortex is divided into areas of specialized functions, including the primary sensory areas for vision (occipital cortex), hearing (temporal cortex), somatic sensation (postcentral gyrus), and primary

Primary Primary somatic motor cortex sensory cortex

Central sulcus

Premotor cortex

Parietal-temporal-occipital association cortex

Primary Primary somatic motor cortex sensory cortex

Central sulcus

Premotor cortex

Prefrontal association cortex

Primary Somatic Sensory Cortex

Primary visual cortex

Sylvian fissure

Primary auditory cortex

The four lobes of the cerebral cortex, containing primary sensory and motor areas and major association areas. The central sulcus and sylvian fissure are prominent landmarks used in defining the lobes of the cortex. Imaginary lines are drawn in to indicate the boundaries between the occipital, temporal, and parietal lobes. (Modified from Kandel ER, Schwartz JH, Jessel TM. Principles of Neural Science. 3rd Ed. New York: Elsevier, 1991.)

Prefrontal association cortex

Primary visual cortex

Sylvian fissure

Primary auditory cortex

The four lobes of the cerebral cortex, containing primary sensory and motor areas and major association areas. The central sulcus and sylvian fissure are prominent landmarks used in defining the lobes of the cortex. Imaginary lines are drawn in to indicate the boundaries between the occipital, temporal, and parietal lobes. (Modified from Kandel ER, Schwartz JH, Jessel TM. Principles of Neural Science. 3rd Ed. New York: Elsevier, 1991.)

motor area (precentral gyrus) (see Chapters 4 and 5). As shown in Figure 7.8, these well-defined areas comprise only a small fraction of the surface of the cerebral cortex. The majority of the remaining cortical area is known as association cortex, where the processing of neural information is performed at the highest levels of which the organism is capable; among vertebrates, the human cortex contains the most extensive association areas. The association areas are also sites of long-term memory, and they control such human functions as language acquisition, speech, musical ability, mathematical ability, complex motor skills, abstract thought, symbolic thought, and other cognitive functions.

Association areas interconnect and integrate information from the primary sensory and motor areas via intra-hemispheric connections. The parietal-temporal-occipital association cortex integrates neural information contributed by visual, auditory, and somatic sensory experiences. The prefrontal association cortex is extremely important as the coordinator of emotionally motivated behaviors, by virtue of its connections with the limbic system. In addition, the prefrontal cortex receives neural input from the other association areas and regulates motivated behaviors by direct input to the premotor area, which serves as the association area of the motor cortex.

Sensory and motor functions are controlled by cortical structures in the contralateral hemisphere (see Chapters 4 and 5). Particular cognitive functions or components of these functions may be lateralized to one side of the brain (see Clinical Focus Box 7.1).

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Responses

  • melanie
    Does the prefrontal cortex integrate skeletal muscle?
    4 months ago

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