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Neural Basis of Language and Set Shifting in Bilinguals Cesar Avila, Gabriele Garbin, Ana Sanjuan, Cristina Forn, Juan-Carlos Bustamante, Aina Rodríguez-

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Presentation on theme: "Neural Basis of Language and Set Shifting in Bilinguals Cesar Avila, Gabriele Garbin, Ana Sanjuan, Cristina Forn, Juan-Carlos Bustamante, Aina Rodríguez-"— Presentation transcript:

1 Neural Basis of Language and Set Shifting in Bilinguals Cesar Avila, Gabriele Garbin, Ana Sanjuan, Cristina Forn, Juan-Carlos Bustamante, Aina Rodríguez- Pujadas, Mireia Hernández & Albert Costa

2 SUMMARY -Some reflections about Spanish-Catalan bilingualism - Language control in bilingualism - Study 1: Language control in Spanish-Catalan bilinguals - Task switching in bilinguals - Study 2: Task switching in Spanish-Catalan bilinguals and monolinguals - Conclusions BrainGlot Barcelona

3 GENERAL PURPOSE At least for some kind of early and high proficient bilinguals, language and cognitive switching would share similar neural mechanisms. BrainGlot Barcelona

4 Spanish-Catalan Bilingualism: Some reflections  Both languages are similar and easy to learn simultaneously.  There are a lot of bilinguals, with a diverse level of proficiency in Catalan.  Bilingualism developed because a person lives in a regional context in which two languages are co-official  There is often a concurrent L1 and L2 development since early infancy  Intense training in both languages BrainGlot Barcelona

5 A good scenario for training executive functions since infancy. For example, one child can speak or hear L1 or L2 as a function of a cue:  Catalan: father, grandparents (father), school, some friends, some relatives....  Spanish: mother, grandparents (mother), at kindergarten, some other friends, some other relatives...  Plus zapping TV, reading, etc.  Involved in continous task switching....Mixing languages becomes effortless. Spanish-Catalan Bilingualism: BrainGlot Barcelona

6  Special case of bilingualism where switching may be trained since early infancy  This implies that the development of some executive functions (response selection, response inhibition, etc.) is intensively trained in parallel to the development of language learning.  Special case for the development of a “passive” bilingualism  A good comprehension but low expression in L2 (See poster) Spanish-Catalan Bilingualism: Some reflections BrainGlot Barcelona

7 Objectives  To study the neural basis of language control in Spanish-Catalan early bilinguals  To study the neural basis of task switching in Spanish-Catalan early bilinguals when compared with monolinguals  To test if both processes share the same neural basis. BrainGlot Barcelona

8 Language control in early bilinguals BrainGlot Barcelona

9 NEURAL BASIS OF LANGUAGE CONTROL Proposed by Abulatebi and Green, 2007 LIFG (Broca’s area) and RIFG: task switching and language control BrainGlot Barcelona

10 Abutalebi (2008) BrainGlot Barcelona

11 Behavioral Studies in language control Picture Naming Task (Costa & Santesteban, 2004) Switching bewteen L1 and L2 L1=Spanish  Red pictures L2=Catalan  Blue pictures Non-Switch Backward Switch Backward Switch Non-Switch Forward-Switch BrainGlot Barcelona

12 PREVIOUS BEHAVIORAL STUDIES Asymmetrical switching costs in low proficient bilinguals: -Switching is slower than non-switching -Naming in L1 from L2 is slower than naming in L2 from L1. -Specific for late bilinguals BrainGlot Barcelona

13 PREVIOUS BEHAVIORAL STUDIES Symmetrical switching costs in early, high proficient bilinguals: -Switching is slower than non-switching -Naming in L1 is slower than naming in L2. -Specific for early bilinguals independently of proficiency (for L3) BrainGlot Barcelona

14 Language control and lexical competition in bilinguals: an event-related fMRI study. Neuroimage Wang et al. (2007) Participants Twelve late bilingual students (6 females) mean age 19.5 (from 18 to 21) L1: Chinese L2: English learnt at 12.67(SD + 1.2) years old (poor proficiency score=3 over 5) BrainGlot Barcelona

15 Wang et al. (2007) “English” (200ms) (2800 ms) BrainGlot Barcelona

16 Wang et al. (2007) Forward switching L1 to L2 Backward switching L2 to L1 BrainGlot Barcelona

17 Neural bases of asymmetric language switching in second-language learners: An ER-fMRI study (Wang et al., 2007) Wang’s conclusion: the neural correlates of language switching differ depending on the direction of the switch and there does not seem to be a specific brain area acting as a “language switch”. But: 3 seconds of ITI is too long to investigate language switching Different types of bilingualism should be considered BrainGlot Barcelona

18 Language control and lexical competition in bilinguals: an event-related fMRI study (Abutalebi et al., 2008) Participants 12 late bilinguals (10 females). L1: German; L2: French; AOA= fMRI tasks Simple Naming (SNc): naming pictures in L1 Task Selection (TSc): naming pictures or generating verbs from pictures as a function of a cue (all in L1) Language Selection(LSc): naming pictures in L1 or L2 as a function of a cue BrainGlot Barcelona

19 Results I (Abutalebi et al., 2008) Abutalebi et al., 2008 Naming L1 in dual vs single task: LIFG, SMA BrainGlot Barcelona

20 Results II (Abutalebi et al., 2008) Abutalebi et al., 2008 Naming L1 in bilingual vs monolingual task: LIFG, RIFG, ACC, bilateral striatum BrainGlot Barcelona

21 Results III (Abutalebi et al., 2008) Abutalebi et al., 2008 Naming L1 in bilingual vs dual task: LIFG, RIFG, ACC and left striatum BrainGlot Barcelona

22 Naming L2 vs L1 in bilingual context: LIFG, RIFG, ACC and bilateral striatum Results IV (Abutalebi et al., 2008) BrainGlot Barcelona

23 Discussion  Results have confirmed Abutalebi and Green’s model involving LIFG, RIFG, ACC and the striatum in language control.  Directional changes from L1 to L2 and vice-versa, were not considered.  Strange results: naming in L1 in bilingual context overactivated the network more than in a monolingual context, but less than naming L2. BrainGlot Barcelona

24 Language control and lexical competition in bilinguals: an event-related fMRI study (Abutalebi et al., 2008) Participants 12 early bilinguals (6 females). L1: Italian; L2: French; AOA= less than 3. More exposed to L2 than to L1 fMRI task Passively listening four types of sentences: 1. Control: L1 2. Control: L2 3. Language switch from L1 to L2. 4. Language switch from L2 to L1.

25  Switch vs non-switching activated the LIFG, RIFG and bilateral superior temporal gyrus. BrainGlot Barcelona Results I (Abutalebi et al., 2007)

26  Forward switching into a less dominant language (L1) activated the left striatum and ventral ACC  Backward switching into a dominant language (L2) did not activate the language control network BrainGlot Barcelona Results II (Abutalebi et al., 2008)

27 Discussion  Switching into a less dominant language activated the language control network, but not switching into a dominant language.  This replicates Wang et al. study BrainGlot Barcelona

28 Study 1: Objective  To replicate Wang et al’s study in early and high proficient bilinguals. Some modifications were made: ITI was 2 sec. Performance was controlled: responses were aloud Cues and pictures were simultaneous- BrainGlot Barcelona

29 Picture Naming Task Participants:19 Spanish/Catalan early bilinguals. - 7 males and 12 females - 11 bilinguals learnt one language at home and the other at the kindergarten, and each father speaks a different language in 8 participants - High proficiency in both Spanish and Catalan. - All subjects were right-handed. - L1 and L2 were determined from infancy data: L1 was Catalan for 11 and Spanish for 8. BrainGlot Barcelona

30 Task Subjects were instructed to name simple pictures in the correct language according to picture colour (red, blue): - Forty-four pictures of common objects with non-cognate names -Interstimuli interval: 2 seconds -Switch and non-switch trials -Responses were aloud. BrainGlot Barcelona

31 Naming sequence BrainGlot Barcelona COMETA / MILOTXA, ESTEL LAVADORA / RENTADORA CERDO / PORC MANZANA / POMA PATO / ÀNEC OJO / ULL

32 Task There were 240 trials: -120 switch trials: 60 Spanish  Catalan 60 Catalan  Spanish -120 non-switch trials: 60 Spanish  Spanish 60 Catalan  Catalan An examiner inside the scanner room registered responses BrainGlot Barcelona

33 Behavioral results. Omissions and commission errors Percentage of errors was low. There were no significant differences between languages in omission errors, but differences in commission errors reached significance (p <.05) BrainGlot Barcelona

34 General Switching Brain regions involved in language switching. The comparison switching (L1  L2, L2  L1) vs. non switching (L1  L1, L2  L2) events result in increased activation in the left striatum (p FWE-cor <.05). BrainGlot Barcelona

35 Forward and Backward Switching Brain regions involved in forward and backward language switching. Activation maps of forward switching (from L1 to L2) relative to L2 non- switching (red cluster) and of backward switching (from L2 to L1) relative to L1 non-switching (blue cluster). BrainGlot Barcelona

36 Discussion  Language swtiching in early and high proficient bilinguals activated the left striatum  This structure have been involved in language selection and switching.  Recent research has specifically involved the left striatum in detecting language changes (Crinion et al., 2006; see Poster Sanjuan et al).  No involvement of ACC and LIFG in language swithing BrainGlot Barcelona

37 Discussion  When directional changes were studied:  Forward switching was associated with the left striatum (as Abutalebi et al., 2007).  Backward switching was associated with the right striatum (see also Wang et al., 2007; Abutalebi et al., 2008). Less is known about the role of this area in language selection. BrainGlot Barcelona

38 Cognitive control in early bilinguals BrainGlot Barcelona

39 PREVIOUS BEHAVIORAL STUDIES  Several studies have evidenced that bilinguals outperform monolinguals in non-linguistic contexts requiring cognitive control, such as Stroop-like tasks (e.g. Bialystok & Martin, 2004; Carlson & Meltzoff, 2008; Costa et al., 2008, 2009; Hernández et al., 2009; Martin-Rhee & Bialystok, 2008).  No previous neuroimaging studies BrainGlot Barcelona

40 PREVIOUS BEHAVIORAL STUDIES. (Costa et al., 2008) Used the ANT task to measure activity in three different attentional networks: alerting, orienting and executive control. Bilingual participants were faster in performing the task Bilinguals were more efficient in the alerting and executive control networks BrainGlot Barcelona

41 PREVIOUS BEHAVIORAL STUDIES. (Costa et al., 2008) They also studied switching costs analyzing the sequence of trials: Switching cost= C-I, I-C > C-C, I-I Monolinguals suffered a greater switching cost than bilinguals This result has been also obtained in children (Bialystok & Viswanathan, 2009) BrainGlot Barcelona

42 Study 2: Objective  To investigate neural basis of task switching in early and high proficient bilinguals and monolinguals.  No previous studies on this topic, but task swithcing has been associated with the RIFG, the striatum and the ACC (Robbins, 2007). BrainGlot Barcelona

43 Participants 19 Spanish/Catalan early bilinguals - 11 bilinguals learnt one language at home and the other in kindergarten, and in 8 each father speaks a different language - High proficiency in both Spanish and Catalan. - All subjects were right-handed. 21 Spanish monolinguals: students from monolingual regions just arrived to Castellon BrainGlot Barcelona Task switching

44 -Scanner: 1.5 T Siemens Task: Subjects were asked to press one of two buttons according to a combination of geometrical pictures CUES: SHAPE OR COLOR. Cues simultaneously presented to pictures. BrainGlot Barcelona Task switching

45 COLOR SHAPE Thumb button Index Button BrainGlot Barcelona

46 Task switching Conditions: -60 Non switch trials: Color-Color or Shape-Shape -60 Switch trials: Color-Shape or Shape-Color BrainGlot Barcelona

47 Behavioral results Switch costs: 32 ms for monolinguals and 4ms for bilinguals (p=0.051) BrainGlot Barcelona

48 Switch costs: 4% for monolinguals and 0% for bilinguals (p <.05) Behavioral results BrainGlot Barcelona

49 fMRI: Monolinguals Increased activity in the left AAC and right IFG

50 fMRI: Bilinguals Increased activity in the LIFG BrainGlot Barcelona

51 fMRI: Bilinguals vs. Monolinguals Bilinguals> Monolinguals: Increased activation in the left inferior frontal gyrus (IFG) (blue cluster). Monolinguals> Bilinguals: Increased activation in the right IFG (red cluster). BrainGlot Barcelona

52 Performance correlates in bilinguals Lower switching costs  Stronger activity in language control areas (striatum and LIFG) BrainGlot Barcelona

53 Performance correlates in bilinguals Higher switching costs  Stronger activity in task switching areas BrainGlot Barcelona

54 Conclusions - Monolinguals have shown significant switching costs and neural activity in brain areas typically related to task switching: RIFG and ACC. -Bilinguals have shown no switching costs and a neural activity in brain areas typically related to language control: LIFG -Bilinguals seem to be an heterogeneous group: those with lower switching costs activate the language control network (LIFG and striatum), whereas those with higher switching costs activate as monolinguals the rIFG. The present results are consistent with the hypothesis that bilinguals' early training in mixing languages leads to the involvement of language control brain areas when performing non-linguistic cognitive tasks. BrainGlot Barcelona

55 General Conclusions  Language swtiching in bilinguals activates brain areas involved in language control: LIFG, RIFG, striatum and ACC. Language control in early bilinguals is more related to the striatum Language control in late bilinguals is more related to ACC. BrainGlot Barcelona

56 General Conclusions  Set-switching in monolinguals is related to rIFG.  Set-switching in early, high proficient bilinguals is related to the language control network: LIFG and the striatum.  Early and high proficient bilinguals may overlap brain areas involved the language and cognitive switching  Future studies should serve to delimitate which factor or factors are responsible for these effects BrainGlot Barcelona

57 Thank You very much.... BrainGlot Barcelona


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