Human Communicatio

nChapter 13

Learning Objectives

1. Describe the use of subjects with brain damage in the study of language and explain the concept of lateralization.

2. Describe Broca’s aphasia and the three major speech deficits that result from damage to Broca’s area: agrammatism, anomia, and articulation difficulties.

3. Describe the symptoms of Wernicke’s aphasia.

4. Discuss the brain mechanisms that underlie our ability to understand the meaning of words and to express our own thoughts and perceptions in words.

5. Describe the symptoms of conduction aphasia and the brain damage that produces them.

6. Discuss research on the brain mechanisms of prosody-the use of rhythm and emphasis in speech-and stuttering.

7. Describe pure alexia and explain why this disorder is caused by damage to two specific parts of the brain.

8. Describe whole-word and phonetic reading and discuss three acquired dyslexias: surface dyslexia, phonological dyslexia, and direct dyslexia.

9. Describe research on the neurological basis of developmental dyslexias.

Speech Production and Comprehension: Brain Mechanisms

LateralizationSpeech ProductionBroca

Speech ComprehensionWernicke

Prosody: Rhythm, Tone and Emphasis in Speech

Stuttering

Lateralization

Lateralization

Temporal Planum65% of population3 monthsL:R

Lateralization

Left Hemisphere Functions

Language SpeakingUnderstandingReadingWriting

AnalyticalLogic

Right hemisphere Functions

Spatial relationsComplex geometrical

forms Organization of a

narrative Expression and

recognition of emotion in voice

Prosody – normal rhythm of speech

Overview of Brain Areas

Speech Production

Posterior cortical areas involved in perceptions of current

events and memories of past events

Frontal lobes conversion of perception, memories and

thoughts into speech

Aphasias

Aphasiaa primary disturbance in the

comprehension or production of speechnot caused by deafness or a simple

motor deficitcaused by brain damage

Boston Diagnostic Aphasia Test

Broca’s Aphasia

Damage to Broca’s area

Characterized by slow, laborious, and nonfluent speech

SpeechFunction words Content wordsCommon Phrases

Broca’s Aphasia

Broca’s Aphasia

Broca’s Aphasia

Agrammatism

Anomia

Comprehension mostly intact

The horse was kicked by the cow

The horse kicked the cow

Speech Comprehension

Comprehension of speech begins in the

auditory systemdetects and analyzes

sounds

Wernicke’s aphasia

Wernicke’s area middle and posterior potion of the left

superior temporal gyrus

Wernicke’s aphasiaPoor speech comprehension Production of meaningless speechGood fluency

Wernicke’s Aphasia

Wernicke’s Aphasia

Disrupted abilities include recognition of spoken wordscomprehension of the meaning of wordsthe ability to convert thoughts into

words

Conduction Aphasia

Arcuate Fasciculus

Characterized by meaningful, fluent

speechrelatively good

comprehensionvery poor

repetition.

Disorders of Reading and Writing

Towards Understanding ReadingDyslexiaAcquiredDevelopmental

Reading processes

Whole-word readingThe, and, rough,

throughIncreases with

fluency

Phonetic reading Phonemes Unfamiliar words

Dyslexia

Surface Dyslexia Phonological Dyslexia

Dyslexia

Visual Word-form area