FUNCTIONAL ORGANIZATION OF THE CEREBRAL CORTEX BY: SHAIKH ASMA AFREEN

FUNCTIONAL ORGANIZATION OF THE CEREBRAL CORTEX Specialized areas of the cerebrum Primary somatic sensory area Receives impulses from the body’s sensory receptors Located in parietal lobe Primary motor area Sends impulses to skeletal muscles Located in frontal lobe Association Areas deal with more complex integrative functions such as memory, emotions, reasoning, will, judgment, personality traits, and intelligence

Interpretation areas of the cerebrum Speech/language region Language comprehension region General interpretation area

Sensory Areas (posterior half behind the central sulci. ) Numbers referenced below are the Brodmann numbers discussed in Figure Primary sensory areas Receive input from lower regions of the brain from peripheral sensory receptors. Secondary sensory areas and sensory association primary areas and from other brain regions.

A person with damage in the primary visual area would be blind in at least part of his visual field, but a person with damage to a visual association area might see normally yet be unable to recognize a friend. • The primary somatosensory area (areas 1, 2, and 3) is located directly posterior to the central sulcus nerve impulses for touch, proprioception (joint and muscle position), pain, itch, tickle, and thermal sensations pinpoint the areas where sensations originate, so that you know exactly where on your body to swat at that mosquito.

• The primary visual area (area 17), located at the posterior tip of the occipital lobe receives visual information and is involved in visual perception. • The primary auditory area (areas 41 and 42), located in the superior part of the temporal lobe near the lateral cerebral sulcus,. • The primary gustatory area (area 43), located at the base of the post central gyrus superior to the lateral cerebral sulcus receives impulses for taste and is involved in gustatory perception. The primary olfactory area (area 28), located on the medial aspect of the temporal lobe and thus not visible in receives impulses for smell

Motor Areas (anterior part) The primary motor area (area 4) is located in the precentral gyrus of the frontal lobe. voluntary contractions of specific muscles or groups of muscles Electrical stimulation of any point in the primary motor area causes contraction of specific skeletal muscle fibers on the opposite side of the body. More cortical area is devoted to those muscles involved in skilled, complex, or delicate movements. For instance, the cortical region devoted to muscles that move the fingers is much larger than the region for muscles that move the toes.

Motor Areas Broca’s speech area (areas 44 and 45) is located in the frontal lobe close to the lateral cerebral sulcus. Speaking and understanding language are complex activities that involve several sensory, association, and motor areas of the cortex. In about 97 percent of the population, these language areas are localized in the left hemisphere. The planning and production of speech occur in the left frontal lobe in most people.

From Broca’s speech area, nerve impulses pass to the premotor regions that control the muscles of the larynx, pharynx, and mouth. The impulses from the premotor area result in specific,coordinated muscle contractions. Simultaneously, impulses propagate from Broca’s speech area to the primary motor area. From here, impulses also control the breathing muscles to regulate the proper flow of air past the vocal cords. The coordinated contractions of your speech and breathing muscles enable you to speak your thoughts

Association Areas (motor and sensory areas) The somatosensory association area (areas 5 and 7) is just posterior to and receives input from the primary somatosensory area, as well as from the thalamus and other parts of the brain. This area permits you to determine the exact shape and texture of an object without looking at it to determine the orientation of one object with respect to another as they are felt, and to sense the relationship of one body part to another. Another role of the somatosensory association area is the storage of memories of past sensory experiences, enabling you to compare current sensations with previous experiences. For example, the somatosensory association area allows you to recognize objects such as a pencil and a paperclip simply by touching them.

The prefrontal cortex (frontal association area) (areas 9, 10, 11, and12). The prefrontal cortex is concerned with the makeup of a person’s personality, intellect, complex learning abilities, recall of information, initiative, judgment, foresight, reasoning, conscience, intuition, mood, planning for the future, and development of abstract ideas. A person with bilateral damage to the prefrontal cortices typically becomes rude, inconsiderate, incapable of accepting advice, moody, inattentive, less creative, unable to plan for the future, and incapable of anticipating the consequences of rash or reckless words or behavior

The visual association area (areas 18 and 19), It relates present and past visual experiences and is essential for recognizing and evaluating what is seen. For example, the visual association area allows you to recognize an object such as a spoon simply by looking at it. The auditory association area (area 22) located inferior and posterior to the primary auditory area in the temporal cortex, allows you to recognize a particular sound as speech, music, or noise.

Wernicke’s (posterior language) area (area 22, and possibly areas 39 and 40), a broad region in the left temporal and parietal lobes, interprets the meaning of speech by recognizing spoken words. It is active as you translate words into thoughts. The regions in the right hemisphere that correspond to Broca’s and Wernicke’s areas also contribute to verbal communication by adding emotional content, such as anger or joy, to spoken words. Unlike those who have CVAs in Broca’s area, people who suffer strokes in Wernicke’s area can still speak, but cannot arrange words in a coherent fashion.