Higher Cortical Functions.pptx
Download as PPTX, PDF4 likes2,189 views
1. The document discusses higher cortical functions including language, vision, object recognition, and awareness, which are carried out by the association cortex. 2. It describes several cortical areas including the primary motor cortex, premotor cortex, motor eye fields, Broca's area, prefrontal cortex, sensory areas, auditory cortex, visual cortex, and language areas. 3. For each area, the location, blood supply, function, and effects of lesions are outlined. The processing of written and spoken language is also summarized.
Higher Cortical Functions.pptx
- 1. Higher Cortical Functions Dr. RUTAYISIRE François Xavier PGY2 Basic Neurosciences module University of Rwanda Supervisor: Dr. MUNYEMANA Paulin
- 3. •The higher cortical functions {COGNITIVE FUNCTIONS} include language, vision, recognizing objects in space (visuospatial recognition), and awareness… •The admittedly vague descriptor for the brain regions that carry out these functions is the association cortex (or cortices)
- 4. Association cortex • Lateral and medial views of the human brain show the association cortices in blue. The primary sensory and motor regions of the neocortex are shown in yellow. • Notice that the primary cortices occupy a relatively small fraction of the total area of the cortical mantle. • The remainder of the neocortex— defined by exclusion as the association cortices—is the seat of human cognitive ability.
- 5. Neocortex • Most of the cortex that covers the cerebral hemispheres is neocortex, defined as cortex that has six cellular layers, or laminae. • Each layer comprises more or less distinctive populations of cells based on their different densities, sizes, shapes, inputs, and outputs.
- 6. Based on variations in the thickness, cell density, and other histological features of the six neocortical laminae, the human brain can be divided into some 50 cytoarchitectonic areas, typically those recognized by the neuroanatomist Korbinian Brodmann in his seminal 1909
- 7. 4 Cortical motor areas • Primary motor area • Premotor area • Motor eye field area • Broca’s area For each cortical area, let’s consider the: • Site • Arterial supply • Function • Effect of a lesion
- 8. Primary motor area • Site: Precentral Gyrus & anterior part of paracentral gyrus • Arterial supply: upper 1/4th and PCL= ACA Lower 3/4th= MCA Representation: Opposite half of the body is upside down 1. Lower third: Head region 2. Leg and foot: Paracentral lobule • Function: 1. Origin to corticospinal and corticobulbar tracts 2. Initiation of fine of the highly skilled fine movements • Lesion: Contralateral hemiplegia with five known signs of UMNLs
- 9. Premotor area • Site: Anterior to area 4 • Arterial supply: upper 1/4th = ACA Lower 3/4th= MCA • Function: 1. Stereotyped movements of muscles through connection with basal ganglia. 2. Planning and execution of learned motor activity by storing the programs of motor activity learned by experience such as walking or dancing • Lesion: Apraxia: difficult performing learned motor activity without paralysis
- 10. Motor eye field area • Site: Posterior part of middle frontal gyrus • Arterial supply: MCA • Function: Horizontal movement of the 2 eyes to the opposite sides • Lesion: Ipsilateral deviation of the 2 eyes due to unopposed action of intact area 8
- 11. Broca’s area #44, 45 • Site: Dominant hemisphere, In the posterior part of IFG 1. Opercular gyrus: area 44 2. Triangular gyrus: area 45 • Arterial supply: MCA • Function: Coordinates the muscles used for speech (Lips, tongue and larynx) for speech production • Lesion : Lesion in Broca's area will cause Motor aphasia; Patients can not form words and is unable to express himself. Th patient can understand and point at object Lesion in the nondominant hemisphere, has no effect
- 12. Prefrontal cortex: Area 9, 10, 11, 12 Personality center • Site: Frontal pole • Arterial supply: ACA, MCA • Function: 1. Make up of the person’s personality 2. Regulations the depth of the person’s feelings and emotional behaviors 3. Higher intellectual function such as production of ideas and judgment. • Lesion: Loss of personality and patient has no appreciation to any social behavior.
- 13. SENSORY areas 1. General sensory area (3, 1, 2) 2. Sensory association area (5, 7, 40) 3. Primary auditory area (41, 42) 4. Auditory association area (22) 5. Primary visual area (17) 6. Visual association area (18, 19) 7. Others: Taste, Olfactory , vestibular
- 14. General sensory area(3,2,1) • Site: Postcentral gyrus & posterior part of paracentral lobule • Arterial supply: Upper 1/4 & PCL: ACA Lower 3/4: MCA • Representation: similar to area 4 Opposite half of the body is upside down 1. Lower third head region 2. Leg and foot paracentral lobule • Function: Receives general sensations from the opposite side of the body & face. • Lesion: Contralateral hemianesthesia
- 15. Somatic sensory association area(5,7,40) • Site: 1. Superior parietal lobule: # 5 & 7 2. Supramarginal gyrus: # 40 • Arterial supply: ACA & MCA • Function: Stereognosis, Interpretation of senses perceived in the general sensory area • Lesion: 1. Astereognosis: inability to recognize objects by the sense of touch with the eyes closed. 2. Unliteral neglect: lesion in area 40 with inability to recognize left from right 40 5&7
- 16. Primary auditory area 41,42 • Site: Middle of the upper surface of the superior temporal gyrus • Arterial supply: MCA • Function: Hearing from the 2 ears. mainly from the opposite ear • Lesion: Bilateral diminution of hearing mainly on the opposite side. Auditory Association Area: Wernicke's Area #22 • Site: posterior part of the superior temporal gyrus • Arterial supply: MCA • Function: recognition of sounds • Lesion: auditory agnosia & sensory aphasia, Inability to understand the spoken languages.
- 17. Primary visual area( Area 17) • Site: Above and below the calcarine sulcus • Arterial supply: PCA • Function: receives optic radiations from LGB for perception of light Representation of the retina: Temporal fibers of the same eye and nasal fibers of the opposite eye 1. Macula: posterior 1/3rd of the calcarine sulcus 2. Upper retinal fibers: Above calcarine sulcus(Cuneus) 3. Lower retinal fibers: Below calcarine sulcus(Lingual Gyrus) • Lesion: Contralateral homonymous hemianopsia with macular sparing.
- 18. Visual association area(18,19,39) • Site: 1. Area 18 and 19: Above and below area 17 2. Area 39: Angular gyrus • Arterial supply: 1. Area 18 and 19: PCA 2. Area 39: MCA • Function: 1. Recognition of what we see 2. Color vision: Inferior association area 3. Angular gyrus: Comprehension of written languages • Lesion: 1. Visual agnosia: Inability to recognize what we see 2. Loss of color vision: Inferior association area 3. Alexia and agraphia: lesion in angular gyrus
- 19. Primary olfactory area(Area 34) • Site: Uncus • Irritative lesion will cause olfactory hallucinations Olfactory association area(Area 28) Site: Anterior part of hippocampal gyrus Function: discrimination of odors Face recognition area(Area 37) Site: posterior part of fusiform gyrus Function: similar to area 19 and 39 1. Face and body recognition 2. Words recognition 3. Numbers recognition Lesion: Prosopagnosia(Face blindness) Inability to recognize familiar faces They can rely on sounds
- 20. Language areas • We have 4 language areas • 1 Motor speech area( Broca's area 44 and 45) Lesion: Expressive(Motor) aphasia • 3 Sensory speech area(22,39,40) • Wernicke's area 22: understand the spoken languages • Lesion: sensory aphasia( Inability to understand the spoken /written languages) • Angular gyrus: Area 39; understand the written languages • Lesion: Agraphia, alexia • Supramarginal gyrus( area 40): Understand shape, size & texture and recognition of the body parts and left side from the right side.
- 21. Processing of written languages E.g: Reading from a book Retina Primary visual area #18,19 for recognition Angular Gyrus to complehent written form Wernickes area to complehent auditory form Brocas area through arcuate fasciculus to formulate words Area 4 Corticobulbar tract VII, X, XII to lips, laryngx and tongue
- 22. Processing of spoken language Muscles of the lips, larynx and tongue VII, X, XII Corticobulbar tracts Area 4 Broca's area through the arcuate fasciculus to formulate words Wernicke's area to comprehend the spoken words Primary auditory area 41,42 Ear Answering a question like: What is your name?
- 23. MMSE
- 24. References • Dale Purves book of neuroscience 6th edition • K.S. Saladin anatomy & physiology: the unity of form and function, 9th edition • JAHANGIR MOINI FUNCTIONAL AND CLINICAL NEUROANATOMY A Guide for Health Care Professionals • Dejong’s The neurologic examination 7th e d i t i o n