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Language and the Brain

Language and the Brain. Study of the neural bases of language development and use. Neuro and Psycholinguistics. Neurolinguistics: the study of the neural and electrochemical bases of language development and use.

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Language and the Brain

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  1. Language and the Brain Study of the neural bases of language development and use

  2. Neuro and Psycholinguistics • Neurolinguistics: the study of the neural and electrochemical bases of language development and use. • Psycholinguistics: the study of the acquisition, storage, comprehension and production of language.

  3. The Brain: Children vs. Adults • Child’s brain trauma and brain Plasticity • http://www.dnatube.com/video/1302/Brain-Plasticity • Adult’s brain trauma and irreversible damage • C.f. Critical Period Hypothesis (CPH)

  4. The Brain: Basics The Hemispheres • Left Hemisphere • Right Hemisphere • Connected by corpus collosum –a bundle of 200 million nerve fibers

  5. The Brain: Basics The Cortex • 1/4” thick layer covering the brain • Makes human capable of higher cognitive functions • Gyri (bumps) • Fissures (depressions)

  6. The Brain: Basics • Sub-cortex • White matter –nerve cell fibers • Reflex actions –breathing, heartbeat, etc.

  7. The Brain: Basics • The Lobes • Frontal Lobe • Parietal Lobe • Temporal Lobe • Occipital Lobe

  8. The Brain: Basics Frontal Lobe • Concerned with reasoning, planning, parts of speech and movement (motor cortex), emotions, and problem-solving.

  9. Dr. Walter Freeman, the Lobotomist Beulah Jones:http://www.pbs.org/wgbh/amex/lobotomist/stories/jones_wm_hi.html Howard Dully: http://www.pbs.org/wgbh/amex/lobotomist/program/lobotomist_11.html

  10. The Brain: Basics Parietal Lobe • Concerned with perception of stimuli related to touch, pressure, temperature and pain.

  11. The Brain: Basics Temporal Lobe • Concerned with perception and recognition of auditory stimuli (hearing) and memory (hippocampus).

  12. The Brain: Basics Occipital Lobe • Concerned with many aspects of vision.

  13. Lateralization and Contralateralizationspecialization of the hemispheres corpus callosum Left hemisphere • Control RIGHTside of body • Language • Analytic reasoning • Time • Arithmetic Right hemisphere • Control LEFT side of body • Music • Non–linguistic sounds • Patterns recognition • Visual and spatial skills

  14. Lateralization and Contralateralization Split Brain Patient with Commissurotomy

  15. Evidences of contralateralization 1. Split–brain patients Corpus callosum is surgically severed, i.e., no communication between left and right Hemispheres. Blindfolded patient cannot say the name of the object put in his/her left hand.

  16. Evidences of contralateralization 2. Dichotic listening test Non-linguistic sounds are processed quickly when heard by the left ear, while linguistic sounds are processed quickly when heard by the right hear

  17. Evidences of contralateralization 3.Hemispherectomy Hemispherectomy involving the left hemisphere results in Aphasia To minimize the damage, brain mapping will precede the operation

  18. Brain Mapping

  19. Left hemisphere of human brain Language Center (on the left hemisphere) • Broca’s area: organizes the sound patterns of language • Wernicke’s area: comprehends words • Arcuate fasciculus: nerve fibers connecting Broca and Wernicke’s area to allow information sharing • Angular gyrus: converts visual stimuli into auditory stimuli

  20. Aphasia • Aphasia is an impairment of language. An acquired communication disorder that impairs a person’s ability to process language, but does not affect intelligence. • Possible causes: • Stroke • TBI (Traumatic Brain Injury) • Aneurism

  21. Aphasia • Broca’s Aphasia • Wernike’s Aphasia • Conduction Aphasia • Global Aphasia • Alexia, • Agraphia

  22. Broca’s Aphasia • Identified by Paul Broca, Neurologist, 1861 • Patient "Tan": intelligent, good language comprehension, severe deficit in speech production • Postmortem: brain showed selective damage at junction of frontal, parietal, temporal lobes, left hemisphere

  23. Broca’s Aphasia: Lesion Site

  24. Broca’s Aphasia • Caused by damage to Broca’s area • An expressive disorder (telegraphic speech, difficulty forming complete words)

  25. Wernike’s Aphasia • Identified 1873 by Carl Wernicke • Patient with reasonably good speech, very poor language comprehension • Autopsy showed selective damage in rear parietal/temporal region, left hemisphere

  26. Wernicke’s Aphasia: Lesion site

  27. Wernicke’s Aphasia • Caused by damage to Wernicke’s area • Comprehension disorder (trouble understanding and interpreting lexicon, incoherent speech)

  28. Conduction Aphasia • The arcuate fasciculus: a bundle of nerve fibers connecting Wernicke’s area to Broca’s, is essential for normal language function. Damage to it causes conduction aphasia. • Speech is“fluent”, auditory comprehension relatively good, but repetition of heard words is impaired.

  29. Global Aphasia • Produce few recognizable words • Understands little or no spoken speech • Can neither read or write Usually seen after patient has suffered a stroke and may rapidly improve if the damage has not been too extensive. Greater brain damage, more severe and lasting disability.

  30. Aphasia • Alexia: an inability to read and comprehend written words • Agraphia: an inability to write words

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