Download Ch12-Language-Brain-1

Language and the Brain (I)
Chapter 12 (pp. 360-371)
Dr. Morten H. Christiansen
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Previous Class:
Genes and Language
Cognitive deficit manifesting itself as a
• SLI:
developmental language disorder
• FOXP2 = language gene?
• Common allelic variation in FOXP2 is associated with
•
individual differences in language and sequential learning
Same genetic basis for individual differences in both
sequential learning and language
all children bring the same genetic biases to bear
• Do
on language acquisition?
•
Common allelic variation in ASPM may lead to differences
in phonological biases relevant for learning tone languages
Language and the Brain:
Aphasia (I)
• Aphasia: A disturbance or loss of language function
as a result of brain damage.
• Stroke, traumatic head injury, or infection.
• Anomia: Access to word forms impaired while
access to semantic concepts is intact.
• Damage to angular gyrus.
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Language and the Brain:
Aphasia (II)
Aphasia: Labored, ungrammatical speech with
• Broca’s
severe word access problems.
to posterior portion of lower frontal lobe:
• Damage
Broca’s area.
Aphasia: Fluent, grammatical but often
• Wernicke’s
meaningless speech with severe comprehension
problems.
to posterior half of temporal area: Wernicke’s
• Damage
area.
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Language and the Brain:
Aphasia (III)
• Conduction Aphasia: Inability to repeat speech.
• Damage to arcuate fasciculus.
• Global Aphasia: All language skills absent but thought
processes are intact.
• Damage to all language areas.
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Language Areas in the Brain
Arcuate Fasciculus
Angular Gyrus
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The Classical Lichtheim-Geschwind Model of
Language Localization in the Brain
• Wernicke’s Area: Representation of sound.
• Broca’s Area: Planning and organization of speech.
• Parietal Lobe (Angular Gyrus): Representation of
concepts.
• Problem: Patterns of symptoms may be a product of
brain damage and patient’s attempts to compensate.
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Neuroimaging Techniques I
• Neuroimaging techniques are noninvasive.
• The brain can be studied without surgery.
• Structural Techniques
• Computerized Tomography (CT)
•
Computer-enhancement of multiple X-ray scans ! 3D image
of the brain.
• Magnetic Resonance Imaging (MRI):
•
Exposes the brain to powerful magnetic fields, and records
voltage reactions (“resonance”) when the fields are turned off.
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Neuroimaging Techniques II
• Functional Techniques: Time-Course of Processing
• Event-Related Potentials (ERPs): Using EEG technology
to record brain waves temporarily linked to the
processing of stimuli.
•
N400 (400 msec late negative shift) ! semantic incongruity.
Neuroimaging Techniques III
• Functional Techniques: Localization of Processing
• Positron Emission Tomography (PET):
•
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Subjects injected with a glucose solution + radioactive isotope.
•
Scanner detects amount of radioactivity (" glucose
consumption) in different brain areas while subjects are
processing stimuli.
Glucose = brain fuel ! high brain activation " high glucose
consumption.
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Neuroimaging Techniques IV
• Functional Techniques: Localization of Processing (cont.)
• Functional Magnetic Resonance Imaging (fMRI):
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Records MRI scans while subjects process stimuli (fine
resolution).
•
Changes in blood flow within the brain can be detected "
changes in brain activation.
•
BOLD (Blood-Oxygen-Level-Dependent) fMRI measures differences in
oxygenated blood.
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Next Class
The Organization of Language
Processes in the Brain
Chapter 12 (pp. 371-386)
• Is there localization of lexical processing?
• Is there localization of syntactic processing?
• Is there localization of integrative processing?