Language and Cognition Colombo, June 2011

1. Language and CognitionColombo, June 2011 Day 5 Aphasia Dissociations

2. Defining aphasia Rao 1994

3. Defining language • Speech? • Communication? • Thought? • A separate system of knowledge? • Double dissociations

4. Double dissociations • Cognitive systems dissociate from one another • One can be impaired while another is (relatively) spared • This is taken as evidence that cognitive systems are distinct – the brain / mind is MODULAR in its organization • There are dissociations within language too

5. Localization of function • Phrenology – Gall, Spurzheim, early 1800s • Different cognitive functions can be localized to different parts of the brain • Level of development of a particular function is reflected in skull formation • The sad tale of Phineas Gage • Dissociation of language from other cognitive faculties

6. Paul Broca (1861): patient ‘Tan’ Slow, effortful, nonfluent speech with many omissions; but good comprehension on parle avec l’hemisphere gauche Carl Wernicke: patients with posterior lesions in the left hemisphere comprehension is impaired but speech is fluent Localization of language

7. Predicted two language centers: Broca’s area: speech articulation Wernicke’s area: speech comprehension Predicted a third ‘disconnection’ syndrome – damage to the arcuate fasciculus “Conduction aphasia” Wernicke’s prediction Chris Rorden, University of Nottingham http://www.psychology.nottingham.ac.uk/staff/cr1/c83lnp/c83lnp2.pdf

8. Wernicke-Lichtheim model Concepts (distributed) Wernicke’s aphasia Broca’s aphasia Wernicke’s area Broca’s area arcuate fasciculus conduction aphasia Conduction aphasia: can produce and understand meaningful speech, but cannot repeat words they hear

9. Wernicke-Lichtheim model • Broca’s aphasia • Wernicke’s aphasia • Conduction aphasia • Transcortical motor aphasia • Dyspraxia • Transcortical sensory aphasia • Pure word deafness

10. Boston classification • Nonfluent aphasias • Broca’s aphasia • Transcortical motor aphasia • Global aphasia • Fluent aphasias • Wernicke’s aphasia • Conduction aphasia • Anomic aphasia • Alexia / Agraphia • Some rare syndromes: pure word deafness, optic aphasia • Boston Diagnostic Aphasia Exam (Goodglass, Kaplan & Barresi, 2001)

14. Classifying the aphasias • Advantages of classifying patients into syndromes • increases interscientist communication • groups homogeneous patients for research and for therapy • describes a set of behaviors for diagnostic purposes • can help in determining a prognosis • contribute data toward localization of lesion - advancing our understanding of the relations between brain and mind • Disadvantages of syndrome approaches • limits thought • exceptions may be more interesting and more fruitful for research • may force a label onto a patient who does not really fall into a particular syndrome category • presumes too much about premorbid functioning • localization issues may be vexed by individual differences

16. Cookie theft descriptions • Cookie jar …fall over…chair…water…empty • Well this is … mother is away here working her work out o' here to get her better, butwhen she's looking, the two boys looking in the other part. One their small tile into here time here. She's working another time because she's getting to. So two boys work together and one is sneakin' around here, making his work an' his further funnas his time he had.

17. Dissociations within aphasia