Aphasias: Language Disturbances Associated with Brain Injury

The Classic View:based on symptoms and associated with particular brain areas

The Major Syndromes:Broca’s aphasia Wernicke’s aphasia Conduction aphasia

Broca’s Aphasia

Sparse halting speechUnderstanding relatively intact

BUT cannot understand sentences like“The cow that was eating the apple was red”

Most function words and inflections omitted

Lesion Site: Posterior portion of left frontal lobe

Cognitive Deficit: speech planning and production ANDparsing

Sample of Speech for Broca’s AphasiaAttempting to describe when he had his stroke, which occurred when he was in a hot tub

Alright…uh…stroke and un…I…h…hot tub and…And the…Two days when uh…Hos…uh…hospital and uh.. am…ambulance

Wernicke’s Aphasia

Poor auditory comprehensionFluent speech but morphological and semantic errors

Lesion Site: Posterior half of temporal cortex

Cognitive DeficitAccessing lexemes for comprehension and production

Sample: Wernicke’s aphasia

Conduction Aphasia

Relatively rare

Disturbance of repetition (with awareness)

Mild disturbance of spontaneous speech

Lesion area: Arcuate fasciculus but more recent analysis questions this

Cognitive deficit:Disconnection of lexemes from speech production mechanisms

Cognitive Model Analysis of Speech ProcessingPure word deafnessPure word meaning deafnessAuditory phonological agnosiaDeep dysphasis

Cognitive Model Analysis of Written Word Processing (Reading)Surface dyslexiaPhonological dyslexiaDeep dyslexia

Cognitive Model Analysis of Auditory Speech Processing

Pure word deafness can talk & read fluently can’t repeat words they can’t understand can’t understand speech addressed to them

Impairment = phonemic processing in the auditory analysis system

Pure Word Meaning Deafness

Can’t understand what words mean when spokenCan repeat wordsCan write words from dictationCan decide what is really a word

Impairment = connection between the auditory lexicon & semantic system

Auditory Phonological Agnosia

Can read aloud & write wellCan’t repeat non-words or words not heard before

Impairment = direct route for repetition via auditory analysis system

Deep DysphasiaCan’t repeat non-wordsMakes semantic errors when repeating back real words

Impairment = access to semantics from auditory input lexicon & direct route from auditory analysis system

Cognitive Model Analysis of Processing Written SpeechSurface Dyslexia

Able to read words if they are regular in their spellingCan read non-words

Impairment = Visual input lexicon

Case: William

Phonological Dyslexia

Can read familiar wordsHas difficulty with non-words & novel words

Impairment = grapheme-phoneme conversion

Case: Ann

Deep Dyslexia

Semantic errors