PSY 369: Psycholinguistics

1. PSY 369: Psycholinguistics Language and the brain

2. Localization of function • Josef Gall’s phrenology • Mental functions (e.g., intellect, morals, etc.) are supported by specific regions of the brain • You can feel the skull to assess people’s mental abilities

3. Localization of function • Modern Neuropsychology • Psychological functions are localized in particular regions of the brain

4. Location of ‘Language Organ’ • Language facilities seem to be primarily located in the left hemisphere (97% of right handers, 81% lefties) • Much of the evidence for the localization of language facilities comes from patients with language disorders • Other evidence from: • “Split-brain” patients • Dichotic listening exps (words presented to the right ear better) • Modern Imaging techniques

5. The “language organ”

6. Language Disorders • Egyptians reported speech loss after blow to head 3000 years ago • Broca (1861) finds damage to left inferior frontal region (Broca’s area) of a language impaired patient, in postmortem analysis

7. Lateralization of the Brain • Human body is asymmetrical: heart, liver, use of limbs, etc. • Functions of the brain become lateralized • Each hemisphere specialized for particular ways of working

8. Left-hemisphere: Sequential analysis Analytical Problem solving Language Right-hemisphere: Simultaneous analysis Synthetic Visual-Spatial skills Cognitive maps Personal space Facial recognition Drawing Emotional functions Recognizing emotions Expressing emotions Music Lateralization of functions

9. Language Disorders • Lateralization In language disorders • 90-95% of cases, damage is to the left hemisphere • 5-10% of cases, to the right hemisphere

10. Language Disorders • Wada test is used to determine the hemispheric dominance • Sodium amydal is injected to the carotid artery • First to the left and then to the right

11. Split-brain • Epileptic activity spread from one hemisphere to the other thru corpus callosum • Since 1930, such epileptic treated by severing the interhemispheric pathways • At first no detectible changes (e.g. IQ) • Animal research revealed deficits: • Cat with both corpus callosum and optic chiasm severed • Left-hemisphere could be trained for symbol:reward • Right-hemisphere could be trained for inverted symbol:reward

12. Motor Cortex Motor Cortex Normal Cortical Connections Language Dominant Side Broca’s Area What changes if the corpus callosum is damaged? Callosal Connections

13. Motor Cortex Motor Cortex The Split Brain Studies Language Dominant Side Broca’s Area Can identify the cat

14. Motor Cortex Motor Cortex The Split Brain Studies Language Dominant Side Broca’s Area The left hand can point to it, but you can’t describe it!

15. Left vs. Right Brain • Pre and post operation studies showed that: • Selective stimulation of the right and left hemisphere was possible by stimulating different parts of the body (e.g. right/left hand): • Thus can test the capabilities of each hemisphere • Left hemisphere could read and verbally communicate • Right hemisphere had small linguistic capacity: recognize single words • Vocabulary and grammar capabilities of right is far less than left • Only the processes taking place in the left hemisphere could be described verbally

16. Other studies • Right ear advantage in dicothic listening: • Due to interhemispheric crossing • Words in left-hemisphere, Music in right • Supported by damage and imaging studies • But perfect-pitch is still on the left

17. Language Disorders • Aphasia – more to follow • Other disorders include • Paraphasia: • Substitution of a word by a sound, an incorrect word, or an unintended word • Neologism: • Paraphasia with a completely novel word • Nonfluent speech: • Talking with considerable effort • Agraphia: • Impairment in writing • Alexia: • Disturbances in reading

18. Broca’s (cortical motor) - slow, effortful halting speech, lacking grammatical words Clinical Aphasia Classifications • Me … build-ing … chairs, no, no cab-in-nets. One, saw … then, cutting wood … working … • Cookie jar … fall over … chair … water … empty … ov … ov … (Examiner: “overflow”] Yeah.

19. Broca’s (cortical motor) - slow, effortful halting speech, lacking grammatical words Clinical Aphasia Classifications • Most also lost the ability to name persons or subjects (anomia) • Can utter automatic speech (“hello”) • Comprehension relatively intact • Most also have partial paralysis of one side of the body (hemiplegia) • If extensive, not much recovery over time

20. Wernicke’s (cortical sensory) - fluent prosodic speech with little or no real content Clinical Aphasia Classifications • [Examiner: “What kind of work have you done?”] We, the kids, all of us, and I, we were working for a long time in the … you know … it’s the kind of space, I mean place rear to the spedwan … [Examiner: “Excuse me, but I wanted to know what work you have been doing”] If you had said that, we had said that, poomer, near the fortunate, forpunate, tampoo, all around the fourth of martz. Oh, I get all confused. • Well, this is … mother is away here working, out o’here to get her better, but when she’s working, the two boys looking in the other part. One their small tile into her time here. She’s working another time because she’s getting, too.

21. Wernicke’s (cortical sensory) - fluent prosodic speech with little or no real content Clinical Aphasia Classifications • Fluent but “empty” speech • But contains many paraphasias • “girl”-“curl”, “bread”-“cake” • Grammatical inflections • Normal prosody • Syntactical but empty sentences • Cannot repeat words or sentences • Unable to understand what they read or hear • Usually no partial paralysis

22. Conduction - fluent speech with good comprehension but impaired repetition and many phonological errors; subcortical pathway between Broca’s and Wernicke’s areas disrupted Clinical Aphasia Classifications

23. Global - broad language impairment across all facets of language; associated with broad lessions Anomic -word finding difficulties; lesions often localized between temporal and parietal lobes Others: Transcortical motor, Transcortical sensory, Mixed transcortical Clinical Aphasia Classifications • Broca’s (cortical motor) - slow, effortful halting speech, lacking grammatical words • Wernicke’s (cortical sensory) - fluent prosodic speech with little or no real content • Conduction - fluent speech with good comprehension but impaired repetition and many phonological errors; subcortical pathway between Broca’s and Wernicke’s areas disrupted

24. Wernicke’s aphasia Broca’s aphasia Vocal tract instructions Phonological structure Syntactic structure Thought Auditory patterns LANGUAGE Linguistic Theory and Aphasia

25. Wernicke-Geschwind Model1. Repeating a spoken word • Arcuate fasciculus is the bridge from the Wernicke’s area to the Broca’s area

26. Wernicke-Geschwind Model2. Repeating a written word • Angular gyrus is the gateway from visual cortex to Wernicke’s area • This is an oversimplification of the issue: • not all patients show such predicted behavior (Howard, 1997)

27. Some problems with the classifications • Under careful study many of the deficits aren’t quite so clear cut: • Broca’s aphasics have comprehension difficulties that are similar to their production problems (but can often compensate for grammatical deficits in comprehension using semantic context) • ~10% of Broca’s aphasics demonstrate Wernicke-like deficits • The classifications typically don’t take linguistic (and psycholinguistic) theories into account

28. Methodologies • Autopsy • Wait until an aphasic died, then examine their brain • fMRI (functional Magnetic Resonance Imaging)

29. fMRI

30. Methodologies • Autopsy • fMRI (functional Magnetic Resonance Imaging) • PET (Positron Emission Tomolgraphy)

31. PET reading hearing speaking thinking and speaking

32. PET by Posner and Raichle • Passive hearing of words activates: • Temporal lobes • Repeating words activates: • Both motor cortices, the supplemental motor cortex, portion of cerebellum, insular cortex • While reading and repeating: • No activation in Broca’s area • But if semantic association: • All language areas including Broca’s area • Native speaker of Italian and English: • Slightly different regions • Due to phonetic alphabet of Italian… (“ghotia”)

33. PET by Damasio’s • Different areas of left hemisphere (other than Broca’s and Wernicke’s regions) are used to name (1) tools, (2) animals, and (3) persons • Stroke studies support this claim • Three different regions in temporal lobe are used • ERP studies support that word meaning are on temporal lobe (may originate from Wernicke’s area): • “the man started the car engine and stepped on the pancake” • Takes longer to process if grammar is involved

36. Methodologies • Autopsy • fMRI (functional Magnetic Resonance Imaging) • PET (Positron Emission Tomolgraphy) • ERP (Evoked Response Potential)

37. ERPs

38. Methodologies • Autopsy • fMRI (functional Magnetic Resonance Imaging) • PET (Positron Emission Tomolgraphy) • ERP (Evoked Response Potential) • Direct stimulation (Penfield technique)

39. Direct Stimulation Gee, this feels kinda’ …….

40. Electrical Stimulation • Penfield and Roberts (1959): During epilepsy surgery under local anesthesia to locate cortical language areas, stimulation of: • Large anterior zone: • stops speech • Both anterior and posterior temporoparietal cortex: • misnaming, impaired imitation of words • Broca’s area: • unable comprehend auditory and visual semantic material, • inability to follow oral commands, point to objects, and understand written questions

41. Studies by Ojemann et al. • Stimulation of the brain of an English-Spanish bilingual shows different areas for each language • Stim of inferior premotor frontal cortex: • Arrests speech, impairs all facial movements • Stim of areas in inferior, frontal, temporal, parietal cortex: • Impairs sequential facial movements, phoneme identification • Stim of other areas: • lead to memory errors and reading errors • Stim of thalamus during verbal input: • increased accuracy of subsequent recall