1. Multilingual Brain By : Prakhar Asthana Entry No.-2011CS1027 Indian Institute of Technology Ropar, India

2. What is Multilingualism There is no one definition. People who speak or have been spoken in two or more languages since birth. Or People who have been speaking one language since birth and later learned other languages. Multilingual Brain2

3. Types of Bilinguals Compound Bilinguals: Has one semantic system but two linguistic codes. Usually refers to someone whose two languages are learnt at same time, often in same context. Coordinate Bilinguals: Has two semantic systems and two linguistic codes. Usually refers to someone whose two languages are learnt in two in distinctively separate contexts Subordinate bilingual: The weaker language is represented to the stronger language. Multilingual Brain3

4. Mental lexicon of bilinguals Multilingual Brain4

5. Hemispherical Lateralization of Language Involvement of one hemisphere of brain to a particular activity makes it dominant Language is believed to be heavily lateralized function, with left hemisphere dominating the right one in handling language related tasks Multilingual Brain5

6. Left hemisphere controls lexical and syntactic language, writing and speech, phonetics and semantics. It does not mean that right hemisphere serves no purpose. Patients which get their right hemisphere surgically removed show no aphasia, but do show deficiencies in verbal selection and metaphor understanding. Multilingual Brain6

7. How multilinguals switch between languages Researchers have used brain imaging techniques like functional magnetic resonance imaging (fMRI) to investigate which brain regions are active when bilingual people perform tasks in which they are forced to alternate between their two languages. Multilingual Brain7

8. When bilinguals have to switch between naming pictures in Spanish and naming them in English, they show increased activation in the : – dorsolateral prefrontal cortex (DLPFC ) – anterior cingulate cortex (ACC) – bilateral supermarginal gyri – left inferior frontal gyrus (left-IFG) Multilingual Brain8

9. Patients with damage or lesion in these parts of brain undergo involuntary change in language while speaking Multilingual Brain9

10. How multilingual’s brain is different? Are areas associated with L1 and L2 same or different? Is Multilingual’s brain structurally different? What about brain activation? Multilingual Brain10

11. A major hypothesis: Different languages, different brain regions. Studies conducted on bilingual aphasiac patients show that in most of the cases only one of the mastered language is affected. This gives an indirect proof to the above mentioned hypothesis. Multilingual Brain11

12. Eye tracking studies show that at early stages of language acquisition both the languages are parallely activated and have shared cortical structures. Multilingual Brain12

13. fMRI scans show that for the late acquitted languages, language sensitive regions in the frontal lobe of brain (Broca’s Area) are spatially separated from that of language sensitive regions of native language But when second language is acquired early, native and second language sensitive areas tend to overlap. Multilingual Brain13

14. But in both late and early bilingual subjects, the temporal-lobe language-sensitive regions (Wernicke's area) also show effectively little or no separation of activity based on the age of language acquisition. Multilingual Brain14

15. fMRI scans show that there are also language specific zones in brain with L2-specific sites located exclusively in the posterior temporal and parietal lobes. Bilinguals possessed seven perisylvian language zones, which are L2 restricted. Multilingual Brain15

16. Structural Changes in Bilingual’s Brain Learning a second language increases the density of grey matter in the left anterior parietal cortex Age of second language acquisition and proficiency in that language affects its extent. Multilingual Brain16

17. Structural Changes in Bilingual’s Brain Multilingual Brain17

18. More brain activation in bilingual brain Cerebral Blood Flow(CBF) measuring techniques show that in word repeating tasks, there is more blood flow in left putamen of brain for second language Multilingual Brain18

19. Word generation has also led to larger foci of brain activation for the second language within multilinguals. Activation is principally found in the left prefrontal cortex (inferior frontal, middle frontal, and precentral gyri). Multilingual Brain19

20. Effect of Age of Acquisition The subcortical organization of languages in bilingual brain can change according to the age of acquisition of second language. Multilingual Brain20

21. Studies done on trilinguals show that more neural substrates of Broca’s Area are engaged in performing same language tasks for later acquired languages. Language Activation follows order L3>L2>L1. Later acquired languages require more activation. Multilingual Brain21

22. Effect of Proficiency in Language Researches show that very early bilinguals display no difference in brain activation for L1 and L2 — which is assumed to be due to high proficiency in both languages. Larger cerebral activation is measured when a language is spoken less fluently than when languages are spoken more fluently. Multilingual Brain22

23. Effect of Proficiency in Language Multilingual Brain23

24. Proficiency V Age of acquisition Generally these go parallelly. But what happens in contradictory case e.g. late proficient bilinguals. Multilingual Brain24

25. Proficiency V Age of acquisition Researches show that proficiency outweighs age of acquisition. Cerebral representation is going to be same for two languages if one is equally proficient in both of them. It doesn’t matter when they were acquired. Multilingual Brain25

26. Bimodal Individuals Bimodal individuals are those who are fluent in both sign language and oral language. PET scans show that there is separate region in the brain related to sign language production and use. Bimodal individuals use different areas of the right hemisphere depending on whether if they are speaking using verbal language or sign-language. Multilingual Brain26

27. fMRI scans show that bimodal bilinguals show greater signal intensity in Wernicke’s area while using both languages in rapid alternation as compared to the oral and sign language monolinguals. Multilingual Brain27

28. Advantages of being Multilingual Bilinguals are more adept than monolinguals at solving certain kinds of mental puzzles. Bilingual people are better than monolingual people at switching between two tasks. Multilingual Brain28

29. For e.g. when bilinguals have to switch from categorizing objects by color (red or green) to categorizing them by shape (circle or triangle), they do so more rapidly than monolingual people. Multilingual Brain29

30. Multilingual Brain30

31. Bilingualism also help adults Bilingualism’s effects also extend into the twilight years. Bilingual adults show delay in onset on alzeihmer’s disease by 4 years. Multilingual Brain31

32. Multilingual Brain32

33. If brain is an engine, bilingualism improves its mileage Actually brains of the bilingual people appeared to be in worse physical condition. This suggest that despite of more brain damage, bilinguals were able to resist more. Multilingual Brain33

34. Bilingualism- always a boon? Researches gives evidence that bilingual children have less vocabulary in one language as compared to monolinguals. They take longer time and make more errors in naming tasks. Multilingual Brain34

35. Multilingual Brain35

36. Questions Still Unanswered Which proficiency level to be declared as bilingual/multilingual? What is the best age at which one should start learning second language? Whether the two languages should be similar or different to get more advantage? Whether there is a limit to no. of languages upto which a person will always be in gain? Whether there are any “better” languages that should be learnt? Multilingual Brain36

37. Reference: Fabbro, Franco. The neurolinguistics of bilingualism: An introduction. Psychology Pr, 1999. Paradis, Michel. A neurolinguistic theory of bilingualism. Vol. 18. John Benjamins Publishing Company, 2004. PERANI, D. (2001). The bilingual brain as revealed by functional neuroimaging.Bilingualism: Language and cognition, 4(2), 179-190. Tierney, Michael C., et al. "PET evaluation of bilingual language compensation following early childhood brain damage." Neuropsychologia 39.2 (2001): 114-121. Kim, K. H., Relkin, N. R., Lee, K. -M., & Hirsch, J. (1997). Distinct cortical areas associated with native and second languages. Nature,388, 171–174. Bialystok, E., Craik, F. I., & Luk, G. (2012). Bilingualism: Consequences for mind and brain. Trends in Cognitive Sciences, 16(4), 240–250 Rönnberg, Jerker, Mary Rudner, and Martin Ingvar. "Neural correlates of working memory for sign language." Cognitive Brain Research 20.2 (2004): 165-182. Multilingual Brain37

38. Thank You