Areas of brain

Functional Areas of Brain

1. AREAS OF BRAIN PRESENTED BY Dr. NERUSU SAI PRIYANKA (PT)

2. OBJECTIVES Areas in Frontal lobe Areas in Parietal lobe Areas in Occipital lobe Areas in Temporal lobe Clinical Implications

3. INTRODUCTION Cerebral cortex is folded into gyri which are separated from each other by sulci. This pattern increases the surface area of the cortex.

4. GYRI AND SULCI Central sulcus separates frontal lobe and parietal lobe Lateral sulcus separates frontal lobe from temporal lobe

5. AREAS OF BRAIN The cortex can be divided into three functionally distinct areas: S ensory M otor and A ssociative. The motor cortex is divided into three areas: Primary motor cortex : Main contributor to the generation of neural impulses that control the execution of movement. Premotor cortex : Located anterior to the primary motor cortex and responsible for some aspects of motor control. Supplementary motor area (SMA ): Functions include internally generated planning of movement, planning of sequences of movement, and the coordination of the two sides of the body. It is located on the midline surface of the hemisphere anterior to the primary motor cortex.

6. AREAS OF BRAIN The main sensory areas of the brain include the primary auditory cortex, primary somatosensory cortex, and primary visual cortex. primary somatosensory cortex : The main sensory receptive area for the sense of touch. primary auditory cortex : A region of the brain that processes sound and thereby contributes to our ability to hear. primary visual cortex : Located in the posterior pole of the occipital cortex, the simplest, earliest cortical visual area. It is highly specialized for processing information about static and moving objects and is excellent in pattern recognition. Associative areas of the cortex integrate current states with past states to predict proper responses based on sets of stimuli.

7. AREAS IN FRONTAL LOBE

8. Primary Motor Cortex (M1, Brodmann area 4) The primary motor cortex is located on the precentral gyrus just rostral to the central sulcus. It is the source of cortical neurons that will project to the brainstem and spinal cord to activate neurons involved in the control of voluntary movements. It receives input from the neighboring primary somatosensory area (S1, on the postcentral gyrus) and premotor cortex, as well as from the ventral lateral nucleus of the thalamus (a relay nucleus with projections from the cerebellum)

9. Premotor Cortex (BA6) The premotor cortex is located immediately rostral to M1. Its primary function is to assist in integration of sensory and motor information for the performance of an action (praxis). Thus it receives input from secondary somatosensory area (immediately caudal to S1 in the parietal cortex) and the ventral anterior thalamic nucleus

10. Broca's area Motor speech area 44, 45 located in Pars triangularis and and pars opercularis Controls the spoken speech

11. Frontal eye fields (BA8) The frontal eye fields are located rostral to premotor cortex. Their primary function is associated with control of voluntary eye movements in the contralateral visual field for processes such as active visual search.

12. Cingulate Cortex/Supplementary motor area (BAs 24, 32) The cingulate cortex is located in the medial portion of the cortex just superior to the corpus callosum. The supplementary motor area is located medial to the premotor cortex just anterior to M1. These regions of the brain have functions that are involved with drive and motivation along with environmental exploration

13. AREAS IN PARIETAL LOBE

14. P rimary somatosensory cortex   The  primary somatosensory cortex  is located in the  postcentral gyrus , and is part of the  somatosensory system At the primary somatosensory cortex, tactile representation is orderly arranged (in an inverted fashion) from the toe (at the top of the cerebral hemisphere) to mouth (at the bottom). However, some body parts may be controlled by partially overlapping regions of cortex. Each cerebral hemisphere of the primary somatosensory cortex only contains a tactile representation of the opposite (contralateral) side of the body.

15. Brodmann area 5,7 BA5 is part of the  superior parietal lobule  and part of the  postcentral gyrus . It is situated immediately posterior to the  primary somatosensory cortex . It is involved in  somatosensory  processing, movement [1] [2]  and  association , and is part of the  posterior parietal cortex BA 7 Situated posterior to the  primary somatosensory cortex  ( Brodmann areas 3, 1 and 2 ), and superior to the  occipital lobe , this region is believed to play a role in  visuo-motor coordination  

16. Wernicke's area BA 22  is located in the  superior temporal gyrus  in the dominant cerebral hemisphere, which is the left hemisphere in about 95% of  right-handed  individuals and 70% of left-handed individuals

17. AREAS IN OCCIPITAL LOBE

18. OCCIPITAL LOBE AREAS Brodmann area 17 : Known as V1, this region is located in the occipital lobe's calcarine sulcus, and serves as the brain's primary visual cortex. It aids the brain to determine location, spatial information, and color data. Visuopsychic Visual area parastriate and peristriate areas 18, 19 Surround the striate area .it aids in Correlation of visual impulses with past memory and recognition of objects seen, and also the depth

19. AREAS IN TEMPORAL LOBE

20. TEMPORAL LOBE Auditosensory 41,42 lobe area : lies at Posterior part of superior temporal gyrus and anterior transverse temporal gyrus Function : Reception and perception of isolated auditory impressions of loudness, quality and pitch Auditopsychic area 22 : lies at Rest of the superior temporal gyrus Function : Correlation of auditory impressions with past memory and identification (interpretation) of the sounds heard

21. CLINICAL IMPLICATIONS

22. MOTOR AREAS Speech area: Lesion of Broca's area on the dominant side of hemisphere causes expressive aphasia. It is characterised by hesitant and distorted speech with relatively good comprehension. A lesion involving language areas that is Wernicke's area and Broca's area both leads to receptive aphasia. In this condition, auditory and visual comprehension of language that is naming of objects and repetition of a sentence spoken by the examiner are all defective. A lesion involving Wernicke's area and superior longitudinal fasciculus or arcuate fasciculus results in jargon aphasia in which speech is fluent but unintelligible jargon.

23. Sensory Areas First somesthetic or general sensory area (areas 3, 1 and 2 of Brodmann). When this part of cortex is the site of destructive lesion, a crude form of awareness persists for the sensation of pain, heat and cold on the opposite side of lesion. There is poor localization of stimulus. There is loss of discriminative sensations of fine touch, movements and position of part of the body. Somesthetic association cortex (superior parietal lobule) areas 5 and 7 of Brodmann: A lesion in this area leads to defect in understanding the significance of sensory information, which is called agnosia. A lesion that destroys a large portion of this association cortex causes tactile agnosia and astereognosis which are closely related.

24. SPECIAL SENSORY AREAS Primary visual area 17 lesion of this area, leads to loss of vision in the visual field of the opposite side-homonymous hemianopia. Auditory area: Primary auditory areas 41 and 42: A unilateral lesion involving the auditory area causes diminution in the acuity of hearing in both ears and the loss is greater in the opposite ear. However, the impairment is slight because of the bilateral projection to the cortex and the deficit is difficult to detect by clinical tests. Auditory association cortex or secondary area22. In lesions of this area, interpretation of the sounds is lost.

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