• Speech Production and Comprehension
• Broca’s aphasia: production difficulties
• Wernicke’s aphasia: comprehension issues
• Disorders of Reading and Writing
• Pure alexia
• Dyslexias

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

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

Brain Regions Involved in Speech Production/Comprehension

• Word recognition is disrupted by damage to superior left temporal gyrus (Wernicke’s 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

• Recognition of spoken words
• Pure word deafness: disruption of inputs to Wernicke’s 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

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

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

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