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FUNCTIONAL AREAS OF CEREBRAL CORTEX [LOBES] 1. Frontal Lobe:- Makes one third (1/3) of cerebral cortex>>>> Primary Motor Cortex (Area 4): - Is located in the posterior portion of thefrontal lobe. It works in association withpre-motorareas to plan and execute movements. - Lesion will cause result in paralysis/paresis (partial loss of movement, or impaired movement) of contra-lateral body area. Pre-motor Cortex (Area 6)- It is responsible for sensory guidance of movement and control of proximal and trunk muscles of the body. - Lesion will cause result in Apraxia (loss of the ability to execute or carry out learned purposeful movements, despite having thedesire and the physical ability to perform the movements). Frontal Eye Field (Inferior Part of Area 8)- Stimulation produces conjugate eye movement to contralateral side. - Lesion produces transient deviation of eyes to ipsilateral side and paralysis of contralateral gaze. Supplementary Motor Area (Parts of Areas 6 and 8)- Stimulation produces posturing responses such as turning head and eyes toward moving arm & Programming for complexmovements involving several parts of the body. Prefrontal Cortex (Areas 9, 10, 11, 12, 32, 46, and 47)- Nearly 1/4 of all cortex & Orbitofrontal area functions in visceral and emotional activities & Dorsolateral area functions inintellectual activities such as planning, judgment, problem solving and conceptualizing. - Lesion will cause loss of initiative, careless dress, loss of sense of acceptable social behavior. Broca’s Area (Area 44 & 45)- language production and language comprehension (It has direct connections for the muscles responsible for the movements of thetongue, lips, vocal cord, and pharynx). o Lesion will cause motor aphaisa (is alanguage disorderin which there is an impairment (but not loss) of speech and of comprehensionof speech.) but only when the dominant hemisphere is involved. The patient knows what he wants to say but speech is slow, deletingmany prepositions and nouns, certain words are skipped and missed or words are repeated. 2. Parietal Lobe:- Includes over one fifth (1/5) of total cortex>>>> Primary Somatosensory (Area 1,2,3)- Stimulation produces contralateral tingling or numbness but never pain. - Lesion will cause contralateral loss of tactile discrimination and position sense but no relief of pain. Primary Gustatory Cortex (Area 43)- perception of taste - Lesion results in contralateral (mostly) ageusia Parietal Association Cortex (Areas 5, 7 ,39 ,40)- 5 input from S1 & 7 input from visual and motor cortex & (39, 40) input from all association areas & function in hand performance & neglect syndrome & astereognosis (a person fails to successfully identify objects by touch when visual information is not used) Parietal neglect syndrome – failure to recognize side of body contralateral to injury. May not bathe contralateral side of body orshave contralateral side of face. Deny own limbs and objects in contralateral visual field ignored. Lesion on the left would lead to noshaving on the right side. You look at the region, but then you forget it plus there is asterognosis. 3. Temporal Lobe:- One fourth (1/4) of total cortex>>>> rPimary Auditory Cortex (Areas 41, 42)- Responsible for processing of auditory(sound) information. - Lesion causes difficulty in recognizing distance and direction of sound, especially when sound comes from the contralateral side. Auditory Association Cortex (Area 22)- Language understanding and formulation. - Damage can result in aphasia (inability to express in terms of speech). This is receptive aphasia; the person will be unable tocomprehend spoken words; the person will speak fluently but without any meaning. Limbic Temporal Cortex (Areas 20,21, 27,28,29,30, 34,36,38)- They are visceral function, emotions, behavior, and memory. Stimulation can elicit past events. Left posterior area memory of verbal info. Right posterior area memory of visual info. - Bilateral lesion of 20 and 21 causes prosopagnosia, loss of facial recognition. Often damaged in alzheimer’s disease. Lesion to thetemporal lobe will eliminate all past memories. 4. Occipital Lobe: primary visual cortex (Areas 17) - Macular vision (isvisionin which eacheyeis used separately. By using the eyes in this way, as opposed bybinocular vision, the field of viewis increased, whiledepth perceptionis limited. The eyes are usually positioned on opposite sides of the animals head giving them the ability to see two objects at once.) in posterior part - Lesion causes homonymous hemianopsia (partialblindnessresulting in a loss of vision in the samevisual fieldof botheyes.) Parastriate cortex (area 18), Peristriate cortex (area 19)- Receive visual info from 17 bilaterally & Complex processing for color, movement, direction, visual interpretation. - Lesion can cause visual agnosia (is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific senseis not defective nor is there any significant memory loss.)
