LANGUAGE, READING, & GENES

1. LANGUAGE, READING, & GENES Timothy C. Bates tim.bates@ed.ac.uk http://www.psy.ed.ac.uk/people/tbates/courses/y2

2. Three lectures: two main parts • Patient Case Studies and Language • Box and arrow models of cognition • Genetics and cognition: • Testing cognitive models using genetics • Genes involved in reading: biological and psychological explanations

3. Outline of part 1 • How should we make models of the mind? • How can we test those models? • How do we get new data to test those models?

4. Where is the mind? • Where is your thinking happening? • It is not obvious that your brain is important • Forward step • Egyptians knew that head injury affected the mind • Backward step • Aristotle (350BC) • Had a lot of the theory right, but the location… • Thought mind was in the heart • Head just a heat radiator

5. The Brain in 1836 • 1836: George Combe (1788-1858) • 1 of 13 children to an Edinburgh Brewer. • His trust founded the Edinburgh Psychology Department with a private grant in 1906 • Reported that if an injury exposed the brain, physically touching the exposed area could cause rather precise alterations in mental function • Anticipates intracranial stimulation and EEG in the 1940s • Also, reported a visible swelling (increase in blood flow) during mental activity • Anticipates the basis of fMRI by 150 years!

6. How shall we represent what is happening in the brain?

7. Richard Feynman:The power of a diagram (c) J. Eric Slone www.FeynmanOnline.com

8. How shall we represent what is happening in the brain? • Brain as informationprocessor

9. Patients, boxes, and arrows Paul Broca (1861) Patient with Brain damage: “Tan” Dysfluent, severe problems with repetition and naming, less severe problems with auditory comprehension Preserved memory, attention and object recognition. Ergo: Language is localized within the brain Cognition is not unitary, but has separable parts

10. Paul Broca Fractionates Cognition X Cognition OtherCognition Language

11. Carl Wernicke (1874) Broca's patient had poor language output Mildly impaired comprehension Severe fluency deficit. By contrast, Wernicke reported a patient with comprehension difficulties: “jargon aphasia” Preserved fluency Very poor comprehension

12. From Broca to Wernicke X X Cognition OtherCognition Language OtherCognition Language Comprehension Language Production

13. Carl Wernicke’s Model: Arrows “Schema of the Psychic Reflex” (1874) a: Acoustic Centre: storage of “auditory word images” b: Motor Speech Imagery a b

14. Cognitive Boxes & Arrows Lichtheim (1885) German-Jewish Physician "The reflex arc consists in an afferent branch aA, which transmits the acoustic impressions to A; and an efferent branch Mm, which conducts the impulses from M to the organs of speech; and is completed by the commissure binding together A and M. When intelligence of the imitated sounds is superimposed, a connection is established between the auditory centre A, and the part where concepts are elaborated, B." B M A m a

15. Bastien 1888: More fractionation Bastien (UK) reported brain damage data with preserved writing, spoken input and output, and poor reading. X OtherCognition SpokenComprehension WrittenComprehension SpokenProduction WrittenProduction

16. Bramwell’s Patient (1897) • 26yr old Scottish woman. • Shortly after giving birth, she had a stroke. • She was left “deaf” to speech. But said… • "Is it not strange that I can hear the clock ticking and cannot hear you speak? Now let me think what that means".

17. Bramwell: Auditory Agnosia“word meaning deafness” • Relevant facts • She can understand print, so … • She retains knowledge of word meanings. • She can hear and understand environmental sounds, so … • She is not deaf. • Why then can't she understand speech?

18. What we know • She can understand print: • Must not have lost all knowledge of word meanings. • She can understand environmental sounds • So she is not deaf • So why can't she understand speech? Non-speech sound Spoken word Printed words Semantics

19. The diagrammatic notation • Boxes • A system of knowledge • System for processing perceptual or cognitive information • Arrows • A pathway of communication between two systems Non-speech sound Spoken word Printed words Semantics

20. Claims of this diagram: 1 • Single system of semantic knowledge • Not one system for each input modality • Auditory stimuli have different pathways to the semantic system • spoken words • non-speech sounds Non-speech sound Spoken word Printed words Semantics

21. Claims of this diagram: 2 • Words use different pathways to the semantic system • spoken words • written words • Interaction is at the semantic level, not before • non-speech sounds, spoken words and written words cannot interact until they have reached the semantic level. Non-speech sound Spoken word Printed words Semantics

22. Building out: Auditory analysis • Both speech and non-speech sounds share early mechanisms of hearing. • How can we add a shared component for speech and non-speech sound? Non-speech sound Spoken word Printed words Auditory processing? Semantics

23. Rules for Arrows • We will need two arrows from auditory processing… • 1 for speech • 1 for non-speech • Is that OK? All sounds Printed words Auditory processing Semantics

24. The diagrammatic notation • Boxes • A system of knowledge • system for processing perceptual or cognitive information • Arrows • A pathway of communication between two systems All sounds Printed words Auditory processing For speech For non-speech Semantics

25. One box per process • If we want to be able to dissociate non-speech from speech, we will need more boxes: More separate processes: All sounds Printed words Early Auditory processing For speech For non-speech ? ? Semantics

26. Three things, then, might explain Bramwell’s patient • We need to: • Eliminate meaning for spoken words • But… • Preserve meaning and hearing for environmental sounds & printed words • Preserve speech All sounds Printed words Early Auditory processing x x Non-speech Speech sounds x Semantics

27. “turbid”Bramwell’s patient & the lexicon • There are spoken words you can recognize as being “real” though you cannot define them. • So… • A store of spoken-forms (words we can recognize) must be separate from a store of word meanings (semantics) for non-speech sound

28. Bramwell’s patient & the lexicon • Path from Auditory Processing to Input Lexicon? • Phonological Input Lexicon itself? • Path from Input Lexicon to Semantic System? ? ? non-speech sound ?

29. A new fact from Bramwell "I asked her … the question: `Do you like to come to Edinburgh?' She did not understand it. I then communicated that I wished her to repeat what I had said: She did so without hesitation. I then asked her to write down the words she had just said. She did so without the words having to be repeated a second time, and she then undoubtedly understood the question.”

30. Which of three lesions preserves spelling? How can she write down “You” and “Edinburgh”? not “Yoo” or“Edinburra” How does she know how these are spelled?

31. Bramwell’s patient & the lexicon • Path from Auditory Processing to Input Lexicon? • Phonological Input Lexicon itself? • Path from Input Lexicon to Semantic System? ? ? non-speech sound ?

32. The necessary lesion for non-speech sounds

33. Non-verbal acoustic Lexicon? • Is there a complementary non-verbal acoustic lexicon? • We need another patient… • Wait 100 years. Lexicon

34. Albert et al (1972) Comprehension of spoken words tested “Point to the X” (shown a range of pictures) 100%correct. Comprehension of sounds Played a tape recording of sounds made objects “Point to object whose sound you are hearing” 10% correct.

35. Final Model here, here or here Lexicon

36. Revision What do boxes do? When do we know we need a new black box? What can arrows do? List the tests given by Bramwell Build the diagram from the tests Next: Association, Dissociation, Double dissociation

37. A case of associated deficits • A patient comes in who cannot: • Tell left-right from right • “Show me your left hand” (cannot do correctly) • Calculate (dyscalculia) • “What is 100 - 7?” (cannot answer accurately) • Express thoughts in writing (dysgraphia) • “Write a sentence” (cannot write) • Distinguish Fingers (finger agnosia) • “Touch your nose with your index finger”

38. Is this association evidence for a left-right-writing-number-finger module? Printed and spoken, and pictorial information Telling left from right, and writing, and calculating and telling one finger from another Moving and talking and writing and moving fingers and hands

39. Gerstmann’s Syndrome (1924) • Spatial location, finger knowledge, calculation, and writing are associated. • Association is evidence for shared processes or shared anatomy • It does not, however, support the hypothesis that the processes are the same: it merely does not rule it out. Tim Shallice (1988) From Neuropsychology to Mental Structure

40. What can we tell if one task is OK, and one is imperfect? • This is called Dissociation • Prima-facie evidence that two tasks differ… • But… what if one task is just harder than another? % correct Amount of Damage

41. Double Dissociation • Subject A: • Significantly better at task 1 than task 2 • Subject B: • Significantly better at task 2 than task 1 • Plausible inference: there are two modules: • One is important for task 1 (but not task 2) • One is important for task 2 (but not task 1).

42. Summary • Association: • Compatible with shared function but also with shared location, blood supply, biochemistry. • Not much help for finding new boxes and arrows • Dissociation: • Compatible with separate functions • Also with compatible differential dependency on a single function (differential task difficulty) • Double Dissociation: • Supports modeling tasks as functionally distinct: two boxes

43. III: Genetic Neuropsychology • Building on Cognitive neuropsychology by incorporating genetics • Examine genetic & environmental influences on cognition • Model separate paths to cognition in genetic and environmental terms. • Test & build new models using genetics • Bates (2008a)

44. Purpose of Genetic Neuropsychology • Describe the functional architecture of the mind using genetic dissociations • Deduce information about how these processes are implemented neurally • Do the genes that build phoneme extractors also build speech processing systems? • How do neurons extract phonemes?

45. Dyslexia • Dyslexia = “difficulty with words” (Berlin, 1884) • Prevalence • Affect up to 17.5% of children despite adequate intelligence, education, and social environment (Shaywitz & Shaywitz, 2005). • Onset • The disorder begins in childhood, continuing into adulthood • (Bates, Castles, Coltheart, Gillespie et al., 2004) • Important negative social impact (Maughan, etal, 1996).

46. Dyslexia is familial • Hallgren, 1950 • Thomas, 1905 • Qu: What does familial mean? • Qu: Why might reading look familial? • Genes, shared environments • Twins allow us to compare these two • MZ twins = Identical genes and Identical family • DZ twins = 50% genes and Identical family • Different families = random genes, random families

47. Heritability: Twins Reared Together • Components of Individual Differences • Random or Unique Environment effect • E = 1 - rmz • Heritable effect(Additive genetic effect) • A = 2 * (rmz - rdz) • Shared or Common Environment • C = (rmz - A)

48. Concepts of Genetic Modeling Reading as the sum of genes, family, and unique effects A = Additive genetic = 2* (rMZ-rDZ) C = Common (family) environment = A- rMZ E = Unique effects and noise = 1-rMZ A C E “Reading”

49. Basic Behavior Genetics • Most of the familial similarity is due to shared genes • Heritability of around 0.7 • DeFries, Fulker, & LaBuda, 1987; Bates et al., 2006; Gayan & Olson, 2003. • Family environment effects prior to school starting • Baker et al, 1997 • Few family effects after school begins • Olson etal (2002); Bates et al 2006

50. Abstract letter units Orthographic lexicon Letter-sound conversion Phonological lexicon Phoneme units Dual Route Cascaded Model (DRC) (Coltheart et al. 2003) • Two tasks in reading aloud: • Access to your store of words • Activate known words from a store “lexicon” • What happens if you look up “GOP” ? • Decoding new words • What sounds (phonemes) correspond to the letters? • How do you say: GOP ? • How do you say: YACHT ?