1. Language, innateness and the brain
LING 200
Spring 2006
Prof. Sharon Hargus

2. Organization Innateness hypothesis Neurolinguistics Lateralization
Localization

3. Innateness hypothesis
Humans are genetically programmed for language.
Humans are equipped with Universal Grammar (UG)
= universal properties of language; structure or phenomena found in all languages
UG severely constrains the possible form that a human language may take.
The actual form of language is determined by environment/language experience.

4. Noam Chomsky
...language appears to be a true species property, unique to the human species in its essentials and a common part of our shared biological endowment, with little variation among humans apart from rather serious pathology. (p. 2)
from (1988) Language and Problems of Knowledge

5. Evidence for innateness hypothesis
lg has characteristics of innate behavior
no other species has a communication system like human lg
brain (and vocal tract) show evidence of specialization for lg

6. Some innate human behaviors
not innate
walking
skating, playing football
speaking or signing a language
reading or writing a language

7. Some characteristics of innate behaviors
language as an innate behavior
Emerges before needed.
Speed of learning L1 (age 5)
Not the result of a conscious decision.
All needed for L1: immersion in lgc environ.
Not triggered by (extraordinary) external events.
‘Poverty of stimulus’: Children exposed to motherese, adult performance

8. Results of chimp studies
Chimps are capable of learning some aspects of human language
Show some spontaneity, creativity
Skills comparable to 1-2 year old child
But chimps lack latent capacity for human language
don't get past 2-3 word stage
limited syntax

9. Neurolinguistics

10. Brain hemispheres
right hemisphere
left hemisphere

11. Lateralization Contra-lateral control
a given hemisphere controls opposite side of body
Left hemisphere controls right side of body
Right hemisphere controls left side of body
Other hemispheric specializations:

12. Right hemisphere specialties
Holistic, spatial processing
pattern-matching (e.g. recognizing faces)
spatial relations
emotional reactions
music (processing by musically naive individuals)

13. Left hemisphere specialties
Sequential processing
rhythm
temporal relations
analytical thinking
music (as processed by musically sophisticated individuals)
mathematics
intellectual reasoning
language, speech sounds
especially so for adult, male, right-handed, literate, monolingual subjects

14. Language processing as a left hemisphere task
Aphasia
Dichotic listening experiments
Split-brain patients

15. Aphasia
Brain injury locations resulting in speech deficits are almost always in left hemisphere
more on some of these locations below

16. Dichotic listening experiments
I.e. stimuli presented to different ears
linguistic sounds: right ear (left brain) advantage
environmental sounds: left ear (right brain) advantage
advantage = correctly identified more often, identified more quickly, etc.

17. Tone in dichotic listening experiments
Tonal contrasts in Thai
[ná:] ‘aunt’ (high) [nâ:] ‘face’ (falling)
[nā:] ‘field’ (mid) [na:] ‘thick’ (rising)
[nà:] (nickname) (low)
Thai speakers process tone with left hemisphere
English speakers presented with tonal contrasts process tone with right hemisphere

18. Split-brain patients
Severe cases of epilepsy treated by severing corpus callosum
corpus callosum (connects hemispheres)

19. Split-brain patients
Task of naming object held in left hand (right brain)
left eye open (right brain), right eye covered
much harder than
right eye open (left brain), left eye covered

20. Effects on lateralization
Lesser left hemisphere specialization for language if:
left-handed
female
illiterate
multilingual

21. Lateralization and handedness
General population
90% predominantly right-handed
10% strongly left-handed or ambidextrous
Lateralization in right-handed individuals
90% left hemisphere specialization for language
10% right hemisphere specialization
75% of general population strongly right-handed

22. Lateralization and handedness
Lateralization in left-handed individuals
most (65-70%) have left hemisphere specialization for language, like right-handed
a larger percentage (30-35%) have right hemisphere specialization or apparently bilateral
Aphasia in left handed individuals
8x more likely to get aphasia if right hemisphere is damaged than right handed individual

23. Lateralization and gender
In women, language may be bilateral more often
if left hemisphere damage, milder aphasia or less likely to result in aphasia
dichotic listening tests don't show right ear advantage as often as for men

24. Lateralization and literacy
Language more symmetrically located in illiterate speakers
Aphasia just as likely with right-hemisphere injury

25. Lateralization and multilingualism
More right hemisphere language dominance than in monolinguals
If right hemisphere damage, multilingual individuals 5x more likely to develop aphasia than monolinguals
Recovery from aphasia
50% recover both languages to same extent
25% do not regain 1 or more languages

26. An aphasic French-Arabic bilingual
French-Arabic bilingual nun in Morocco became severely aphasic after moped accident
initially lost speech altogether
4 days after accident, could speak a few words of Arabic, no French
14 days after accident, could speak French fluently
15 days after accident, could speak only Arabic fluently

27. Lateralization and modality
Sign languages use visual-spatial mode of transmission
How is lateralization for language affected by modality?
Results of a study of aphasia and other problems in 6 ASL signers
3 left brain damage, 3 right brain damage
No effect of language modality on lateralization for language; left hemisphere specialization for language even for signed languages

28. If left hemisphere was damaged
Sign language aphasia resulted
GD: ‘halting and effortful signing,’ reduced to single sign utterances
KL: ‘selection errors’ in formation of ASL signs, ‘sign comprehension loss’
PD: fluent signing but impairment in sentence structure

29. If right hemisphere was damaged
Non-aphasic problems resulted
Right-hemisphere damaged signer
avoided left side of signing space
describing furniture in a room: ‘furniture piled in helter-skelter fashion on the right, and the entire left side of signing space left bare...’
but used left side of signing space better when such uses were linguistically required

30. Localization for language
I.e. localization within hemisphere
Hypothesis: specific parts of brain control specific parts of body or bodily functions, including language

31. Some language centers (left hemisphere)
Broca’s
Wernicke’s
Arcuate fasciculus

32. Broca’s area
Lesions to Broca’s area result in Broca's aphasia (a.k.a. expressive aphasia, motor aphasia)
Characteristics of Broca’s aphasia
basic message of meaning clear, but
speech is not fluent
phrases are telegraphic (absence of function words)
incorrect production of sounds
Cinderella, as told by a Broca’s aphasic
Cinderella...poor...um ‘dopted her...scrubbed floor, um, tidy...poor, um...’dopted...si-sisters and mother...ball. Ball, prince um...shoe.

33. Wernicke’s area
Lesions to Wernicke’s area result in Wernicke’s aphasia
Characteristics of Wernicke’s aphasia
speech is fluent, but
often nonsensical or circuitous
Description of a knife by a Wernicke’s aphasic
‘That’s a resh. Sometimes I get one around here that I can cut a couple regs. There’s no rugs around here and nothing cut right. But that’s a rug and I had some nice rekebz. I wish I had one now. Say how Wishi idaw, uh windy, look how windy. It’s really window isn’t it?’

34. Arcuate fasciculus
Subcortex nerve fibers connecting Broca’s, Wernicke’s areas
Lesions at this area result in:
Conductive/conduction aphasia
Characteristics
usually good comprehension, fluent speech but
difficulty repeating
difficulty reading out loud
difficulty writing

35. Angular gyrus Lesions at angular gyrus Anomia Reading difficulties
difficulty finding words, especially names
Reading difficulties

36. Other evidence for localization
Electrical stimulation of brain
Normal reaction: numbness, twitching, movement of contralateral body part
Electrical stimulation at ‘language centers’
Results in
difficulty talking
some kind of vocalization

37. Further complexities in localization
Factors: spoken vs. written language, parts of speech
Johns Hopkins study of 2 female aphasics
both found it easy to read, speak and write nouns
one could speak verbs but not write them
one could write verbs but not speak them

38. More than language centers in the brain
Broca's aphasics
damage to Broca’s area results in
language deficits
motor control problems
problems with cognitive and perceptual tasks
Alzheimer’s disease
non-localized neurological problems result in language deficits (among other problems)
i.e. ‘lg centers’ control more than lg
i.e. damage to parts other than lg centers can have consequences for lg

39. Neurolinguistics summary
Hemispheres of brain have different specialties, including language (most clearly for right-handed (etc.) individuals)
Lateralization is not affected by language modality
Language centers within the brain: Broca's, Wernicke's areas especially important
Neurolinguistics provides evidence for human specialization for language

40. Next time
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