Chapter 13: Human Communication

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Chapter 13 Human Communication
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Lecture Outline

• Speech Production and Comprehension
• Brocas aphasia production difficulties
• Wernickes aphasia comprehension issues
• Disorders of Reading and Writing
• Pure alexia
• Dyslexias

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Speech Disorders

• Aphasia
• Disturbance in speech
• Production
• Comprehension
• Aphasia is not the result of
• Lack of motivation
• Sensory/motor deficit (e.g paralysis)
• Left hemispheric damage

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Brocas Aphasia

• Damage to inferior left frontal lobe
• Evidence for hemispheric lateralization
• Characteristics of Brocas aphasia
• Slow, laborious speech (but can comprehend
  speech)
• Difficulty with function words (a, the, in,
  about)
• Three major difficulties in Brocas aphasia
• Agrammatism difficulty in using grammar rules
  (e.g. -ed)
• Anomia difficulty in finding appropriate words
• Difficulty with articulation

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Wernickes Aphasia

• Word recognition is disrupted by damage to
  superior left temporal gyrus (Wernickes area)
• Poor speech comprehension
• Evident in non-verbal tasks (point to object)
• Cannot repeat statements made by others
• Fluent but meaningless speech
• Patients can use content words, appropriate
  grammar
• Patients are unaware of comprehension deficit

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Speech Comprehension Deficits

• Recognition of spoken words
• Pure word deafness disruption of inputs to
  Wernickes area
• Comprehension of word meaning
• Transcortical sensory aphasia damage to
  posterior language area
• Can repeat statements, but does not comprehend
  the statements
• Suggests distinction between speech
  recognition/comprehension
• Conversion of thoughts into words

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Conduction Aphasia

• Information about word sounds is carried via the
  arcuate fasciculus
• Connects Wernickes area with Brocas area
• Damage to the fasciculus produces conduction
  aphasia
• Fluent, meaningful speech
• Good word comprehension
• Difficulty in repeating words

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Prosody

• Prosody variations in rhythm, pitch, and cadence
  that communicate information
• Distinguish questions from statements
• Communicates our emotional states
• Prosody is not disrupted in Wernickes aphasia
• but is severely disrupted by damage to the right
  hemisphere (musical aspect of prosody)
• and by damage to Brocas area

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Reading Disorders

• Pure alexia inability to read
• Damage to left visual cortex and posterior end of
  the corpus callosum
• Flow of information during reading
• retina --gt striate cortex --gt extrastriate --gt CC
• contralateral extrastriate --gt Wernickes A. --gt
  Brocas A.
• Pure alexia word recognition carried out by
  right extrastriate cortex cannot reach left hemi.
  speech regions

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