1. Aphasia
“Impairment of central language abilities in the speech modality following brain damage.“
In contrast to:
peripheral speech problems (dysarthria)
non-linguistic cognitive impairments
impairments of writing and reading
loss of language due to psychotic states, congenital or developmental structural abnormalities
problems of language acquisition

2. Language Impairments COMPREHENSION Auditory Single words Phrases
Commands (Token Test)
Syntax
Visual (Reading - alexia)
PRODUCTION
Spontaneous Speech
Fluent versus nonfluent
Unintended or “off” words (paraphasias)
Word finding difficulties (anomia)
Poor articulation
Prosody (aprosodia)
Repetition
Single words
Phrases
Writing (agraphia)

3. Broca’s Aphasia
Bouillaud (1825): large series of speech loss with frontal lesions
Marc Dax (1836): LH damage, right hemiplegia, & aphasia linked
Paul Broca (1861) convincing evidence of speech laterality; Tan “Nous parlons avez l’hemispheregauche”
Paul Broca ( )

4. Broca’s aphasia Damage to Broca’s area results in: slow labored speech
little grammatical fluency
omission of function words
omission of inflections
word finding difficulty
comprehension may be impaired

5. Wernicke’s aphasia Damage to Wernicke’s area results in:
Loss of meaningful messages
But fluent and grammatical
paraphasias or inappropriate words
neologisms - invented words
language comprehension difficulty, especially with complex sentences

7. Carl Wernicke (1874) reports that temporal lobe lesion disturbs comprehension.
Developed connectionism model of language and predicated conduction aphasia

8. Wernicke-Geschwind Model (1965)
Auditory
cortex
Visual
cortex
Angular
gyrus
Wernicke’s
area
Wernicke’s area translates verbal information into thought, and vice versa
Broca’s area translates verbal information into vocal, and vice versa (i.e., articulation)
Pathway between areas: arcuate fasciculus
Broca’s
area
Motor
cortex

10. Aphasias Wernicke’s Broca’s Fluent speech Non-fluent speech
Poor comprehension
Poor repetition
Poor naming
Posterior superior temporal lobe lesion (first temporal gyrus)
Global
Non-fluent speech
Lesion involves frontal, temporal and parietal lobes, Including Broca’s and Wernicke’s area
Broca’s
Non-fluent speech
Good comprehension
Poor repetition
Poor naming
Posterior inferior frontal lesion
Conduction
Fluent speech
Lesion in arcuate fasciculus or its connections in inferior parietal lobule

11. Aphasias Anomia Fluent speech Good comprehension Good repetition
Poor naming
Temporal or temporo-parietal lesion
Mixed Transcortical
Non-fluent speech
Poor comprehension
Anterior and posterior association cortex lesions while sparing perisylvian language region
Transcortical Motor
Non-fluent speech
Good comprehension
Good repetition
Poor naming
Lesion involves frontal lobe but spares Broca’s area
Transcortical Sensory
Fluent speech
Poor comprehension
Lesion in posterior temporo-parietooccipital junction while sparing Wernicke’s area

12. Anomia and categorical label storage in temporal lobe

14. Lateralization from Functional Neuroimaging

15. Individual Differences in Language localization
Wilder Penfield, 1930s: Electrical stimulation leading to language disruption, others produce episodic memories

16. Language of Split Brain Patients

17. Chronic Callosal Disconnection Syndromes
Social ordinariness
Lack of interhemispheric transfer (undetectable by normal means)
Inappropriate politeness
Alexithymia – inability to discuss emotions
Self-focus
Joe Bogen
performed 1st series of surgeries

18. Mystery of Right Hemisphere Language
Focal damage in left hemisphere produces aphasias (Broca, Wernicke, etc), but removal of entire left hemisphere allows right hemisphere verbal functioning
Why?
Roger Sperry, Nobel Laureate, 1981

19. Spreading Activation
butter
gate
bread
castle
cheese
path

20. Spreading Activation
Collins & Loftus (1975) rejected the notion of a strict hierarchical
structure

21. Errors can revealed type of dysfunction

22. Deep Dyslexia