07b posterior association cortex


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07b posterior association cortex

  1. 1. Association cortices
  2. 2. Motor Sensory Association
  3. 3. Somato Sensory Pathway
  4. 4. Sensory Cortex Receptive Field
  5. 5. Two Point Discrimination
  6. 6. Columnar organization of somatosensory cortex
  7. 7. Sensory Cortex Area 5 integrates tactile information from mechanoreceptors in the skin with proprioceptive inputs from the underlying muscles and joints. This region also integrates information from the two hands. Area 7 receives visual as well as tactile and proprioceptive inputs, allowing integration of stereognostic and visual information. The posterior parietal cortex projects to the motor areas of the somatic frontal lobe and plays an important Proprioceptiv role in sensory initiation and e guidance of movement.
  8. 8. Association Cortex Information Flow
  9. 9. Pattern of Vibration of the Basilar Membrane
  10. 10. The Auditory Cortex
  11. 11. Discrimination of Sound “Patterns” by the Auditory Cortex
  12. 12. Pathways to the somatosensory, visual, and auditory association areas
  13. 13. Visual Pathway
  14. 14. AIT = anterior inferior temporal area; CIT = central inferior temporal area; LIP = lateral intraparietal area; Magno = magnocellular layers of the lateral geniculate nucleus; MST = medial superior temporal area; MT = middle temporal area; Parvo = parvocellular layers of the lateral geniculate nucleus; PIT = posterior inferior temporal area; VIP = ventral intraparietal area.) (Based on Merigan and Maunsell 1993.)
  15. 15. Pathways to the somatosensory, visual, and auditory association areas
  16. 16. Unimodal sensory inputs converge on multimodal association areas
  17. 17. Interaction Among Association Areas Leads to Comprehension, Cognition, and Consciousness
  18. 18. Emotion Localization
  19. 19. Parietal Lobe
  20. 20. Left Hemisphere Cortical Sensory Loss Disorder of language Fluent aphasia, alexia Gerstman’s syndrome (Angular gyrus) acalculia, finger agnosia, left/right disorientation, agraphia Tactile agnosia (bimanual asteriognosis) Bilateral Ideomotor & ideational apraxia
  21. 21. Right hemisphere Cortical Sensory Loss Topographic disorientation Topographic memory loss Anosognosia /dressing apraxia Constructional apraxia Hemi-inattention Apraxia of eye opening Confusion
  22. 22. “Attention Neurons” in the Monkey Parietal Cortex
  23. 23. Attention activity of Right Parietal Cortex in Normal
  24. 24. Contralateral Neglenct Syndrome
  25. 25. Temporal Lobe
  26. 26. Either Temporal dysfunction Auditory – Threshold of brief auditory stimuli elevated – Spoken words less clear – Distorted words are less clear – Difficulty in equalizing sound presented to both ear – Rapidly presented words and number in both ear difficult to perceiving Hallucination – Auditory, – visual, – olfactory and – gustatory Emotional and behavioral changes Delirium
  27. 27. Left temporal dysfunction Auditory deficits (right ear) – Intracranial localization of sound is impaired. – Increased threshold for perception of short bursts of sound. – Increased threshold for some frequencies. – Failure to perceive brief simultaneous auditory stimulation. Visual deficit (both eyes) – Upper right quadrantanopsia. Other complex sensory deficits – Right hand tactile performance difficulty. – Right hand finger agnosia.
  28. 28. Left temporal dysfunction Language deficits – Decoding of speech sounds (phonemes) is impaired. – Problems with verbal repetition. – Problems with auditory comprehension of speech. – Receptive aphasia (deficits in all language qualities). – Impairment of dichotic listening to verbal material. – Intellectual impairment on verbally mediated intellectual processes. Memory impaired for verbal material. Emotional disturbances – Perceptual distortions, alterations of mood, obsessional thinking, psychosis, temper outbursts, hypo and hypersexuality
  29. 29. Right Temporal dysfunction Right temporal lesion effects tend to be 3. Auditory analysis (nonverbal) notable statistically but of less – Impairment of short-term auditory clinical significance. memory. 1.Visual analysis (nonverbal primarily) – Perception of short sounds – Impairment of simple and complex impaired. visual analysis, but some negative – Impaired recognition of familiar findings. sounds. – Impairment of short-term – Impaired tonal discriminations, nonverbal memory. timbre discriminations, and – Impaired perception of amplitude discriminations. tachistoscopically-presented letters. – Amusia. – Prosopoagnosia (especially with – Impairment of contralateral ear anterior lesions). input in dichotic listening. – Impaired recognition of objects seen from unusual angles
  30. 30. Right Temporal dysfunction 4. Constructional tasks 6. Psychometric findings – Visual construction impairment – Temporary decline in proportional to tissue loss. Performance IQ following – Impairment in maze learning lobectomy. (visual and proprioceptive – Impairment on WAIS Picture feedback). Arrangement. – Enlarged left-hand margin in – Impairment on Binet Memory dictation. for Designs 5. Psychiatric personality – Possible impairment of WAIS phenomena with right temporal Block Design?. epilepsy 7. Persistence in maintaining a – Personality changes. hypothesis even after being – Psychiatric symptoms. informed it was not correct. – Deja vue. – Metamorphopasias.
  31. 31. Bitemporal dysfunction Human bitemporal lesion – Kluver bucy like + aphasia, amnesia and bulimia Bilateral inferior and medial temporal lesion – Sham rage like – React to every stimuli with extreme belligerence, screaming, cursing , biting and spiting Bilateral post cortical lesion – Cortical deafness – unaware of deafness Korsakoff amnesic defect
  32. 32. Selective activation of face cells in the inferior temporal cortex of a rhesus monkey
  33. 33. Prosopognosia
  34. 34. Occipital Lobe
  35. 35. Unilateral occipital lesion Contralateral (congruent) homonymous hemianopia, may be central (spitting the macula or peripheral Homonymous hemiachromatopsia Elementry unformed hallucination – irritative lesions
  36. 36. Left occipital lesion Right homonymous hemianopia Alexia and color naming defect with deep white matter or splenium of corpus callosum involved Visual object agnosia
  37. 37. Right occipital lesion Left homonymous hemianopia Visual illusion, (metamorphopsias), and hallucinations Loss of topographic memory and visual orientation
  38. 38. Bilateral occipital lesions Cortical blindness Anton syndrome Loss of perception of color Prosopognosia and simultagnosia Balint syndrome
  39. 39. Balint Syndrome (Bilateral parietooccipital region) An inability to look voluntarily into the peripheral field, with normal eye movements (psychic paralysis of fixation gaze) A failure to precisely grasp or touch an object under visual guidance, hand and eyes in- coordinated (optic ataxia) Visual inattention affecting mainly the periphery of the visual field, attention to other sensory stimuli being intact Failure to properly direct occulomotor function in the exploration of space (amorphosynthesis)
  40. 40. Thank You