1. ADULT LANGUAGE DISORDERS Week 1 Jan 13, 2011

2. Text Book LaPointe, L. L. (2005). Aphasia and Related Neurogenic Language Disorders. 3rd edition, Thieme, New York. ISBN: 1-58890-226-9

3. Outline Brain and behavior relationships, specific to language processing Review neural structures implied in language processing Levelt model of lexical access in speech production

4. Language Processing Understanding language processing in normal adults can help us understand the compromised language system following brain damage. – Functional neuroanatomy (parts of the brain and what they do) – Computational structure of language processing(how does it work, how is it responsible?)

5. Language Processing Our understanding of functional neuroanatomy for language originally came to us through lesion studies – Broca, Wernicke, Charcot, Litchtheim and other scientists laid foundation for relating language processing to the brain.

6. Language Processing Findings of lesion studies – 1. Language processing is subserved by neural structures in left hemisphere – 2. Highly articulated functional organization within the hemisphere (i.e., different parts assuming different roles)

7. Perisylvian region Caramazza, 1988, pg.398

8. Language Processing Components of language processing – Syntactic – Morphological – Lexical-semantic – Phonological – All the above processes are served by the perisylvian region of the left hemisphere

9. Language processing Right hemisphere – Supportive role in language processing – Appreciation of irony, metaphor, and humor – Emotional content of linguistic act Caramazza, 1988, pg.398

10. Language Processing Some thoughts about lesion studies: – Large lesions involving both cortical and subcortical areas – Complex language deficits (naming, sentence production, etc.) – Compensatory strategies to overcome functional deficits – Therefore, correlating lesion site with behavioral performance may mask the language problem. – Also, lesioned area of the brain can be part of complex distributed language network

11. Language processing Cortical stimulation mapping/WADA techniques – Performed during neurosurgical procedures – Subjects are typically neurologically compromised – It may not provide information how language operates in normal brain.

12. Language Processing Neuroimaging studeies Understand the language in non-damaged brain individuals Can examine distributed language networks and their processing of language information Researchers can precisely identify areas associated with lexical-semantic processes and syntactic processing

13. Neuroimgaing Techniques http://psychology.uwo.ca/fmri4newbies/

14. PBS video http://www.pbs.org/wnet/humanspark/episodes/pr ogram-three-brain-matters/video-full-episode/418/ http://www.pbs.org/wnet/humanspark/episodes/pr ogram-three-brain-matters/video-full-episode/418/

15. Language Processing Price et al., 1997 – Series of fMRI experiments – Isolate brain mechanisms involved in various components of naming process – Naming pictures Vs viewing nonsense figures and saying “okay” – Reading words silently Vs viewing consonant letter strings http://www.psych.upenn.edu/stslab/assets/images/picagree.jpg

16. Language Processing Price et al., 1997 – Results showed activation of frontal opercular area for both reading and naming. – This area may be involved in the stage of lexical access in which phonological form of a word is constructed (prior to ariculatory processes) – These findings confirm lesion studies: Patients with lesions to this area show naming deficits http://www.psych.upenn.edu/stslab/assets/images/picagree.jpg

17. Language Processing Along with frontal areas, word production also activated the left posterior ventral temporal lobe (BA 37) It is also crucial for lexical retrieval Temporal lobe has been implicated in several word production studies investigating categories of objects i.e., tool naming Vs animal naming Naming “photographs of persons” produced bilateral temporal lobe activation Manmade objects Vs natural objects (bilateral) Findings indicate that regions within temporal lobe, beyond Wernicke’s and surrounding areas are involved in naming. http://upload.wikimedia.org/wikipedia/commons/7/71/Brodmann_area_37. png

18. Language Processing Language processing at sentence level Bilateral recruitment of both anterior (Broca’s and surrounding) and posterior (Wernicke’s and surrounding) brain sites. Friederici (2000) found bilateral recruitment of the superior temporal regions in the processing of “syntactic prose” http://williamcalvin.com/bk7/img/bk7p245.jpg

19. Language Processing Language processing at sentence level Studies have also shown Broca’s area activation in left hemisphere is associated with processing complex syntactic constructions and right with simpler (Caplan et al., 1998, 199) Just et al 1996 found both left Broca and Wernicke area activation under complex sentence processing conditions. Activation is also noticed in right hemisphere but with lesser extent. These difference could be due to variation in task demands

20. Speech Perception Salmelin, R. (2006). The clinical neurophysiology of language: The MEG approach. Neurophysiology

21. Speech Production

22. Summary- Take home More brain sites from LH have been implicated in language processing in normal individuals Recruitment of right hemisphere sites for language processing Extra perisylvian mechanisms are involved in language processing

23. Lateral view of LH

24. Medial view of RH

25. Language Processing A THEORY OF LEXICAL ACCESS IN SPEECH PRODUCTION (Levelt, 1993) Preparing a word proceeds through stages of 1. conceptual preparation 2. lexical selection, 3. morphological and phonological encoding 4. phonetic encoding 5. articulation. In parallel there is output monitoring involving the speaker's normal speech comprehension mechanism.

26. LH vs RH Left Hemisphere – 1. LH has very fine resolution for both verbal and nonverbal information – 2. Strength of LH is way in which it attacks information – 3. LH is better at learning routines – 4. LH appears to process information sequentially, analytically, and rationally.

27. LH vs RH Right Hemisphere – 1. RH is better at integrating information across modalities – 2. RH is better at handling novel information – 3. RH processes information holistically, simultaneously, and intuitively

28. LH and RH Anatomical Differences Between Two Hemispheres A. Planum Temporale – Upper posterior surface of temporal lobe is usually larger on left than right hemisphere – Region forms part of Wernicke’s language comprehension area – This asymmetry is associated with a longer Sylvian fissure on the left side. – Anomalous patterns of asymmetry have been reported in the brains of dyslexics and people who stutter. – The MRI findings have confirmed the concept of relation between anatomical asymmetry and functional laterality in both Wernicke’s area and Broca’s area. – B. Angular gyrus: appears to be larger in RH than LH