1.1. Defining Human Language
1.2. Context of the Longitudinal Study
1.3. Fundamentals of the Common European Framework Proficiency Scale and Specifics of LfMRI SLAM
- A: Basic User
- A1 Breakthrough or beginner; A2 Waystage or elementary
- B: Independent User
- B1 Threshold or intermediate; B2 Vantage or upper intermediate
- C: Proficient User
- C1 Effective Operational Proficiency or advanced; C2 Mastery or proficiency
- L2/L3 proficiency of five subjects:
- French/C1, AP 5, SAT II-800, Italian/B1
- German/B2/C1, AP 5, IB HL-6, Arabic/B1
- French/A1, Italian/A1
- Spanish/SAT II, AP 5
2. Background and Significance
2.1. Results from Previous Studies
2.2. Methodological Considerations
2.2.1. Research Questions: Hypotheses and Rationale
- Is there a significant neurological variation in the organization of language-related areas in the brains of multilingual subjects who are equivalent in language facility and age of acquisition (pre-adolescent)? Previous research has suggested that “early” bilingual or multilingual acquisition is represented differently in the brain than “late” second or third language acquisition ([31,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,69]). These studies have produced results that are not consistent and inconclusive. The data collected from longitudinal studies of multilingualism will be an important contribution to solving this controversy and providing a more dynamic and empirically-valid view of neurological representations of language(s) in the human brain.
- What types of changes will occur within a single subject during periods of language acquisition and maintenance over a period of one, two or more years?
- How can fMRI facilitate an understanding of how (not merely where) language is acquired and maintained neurologically?
- How well do the behavioral and imaging data map onto each other?
- Some research has suggested that there is a difference in language-related areas in the brains of multilinguals depending on age of acquisition ([69,70]). We will address the definition of age as a variable using de Bot ([1,20]) and will compare subjects in our study who have used two or more languages across different age spans and in different contexts to test for support or lack therein for such a claim. We hypothesize that proficiency may be a more important variable than biological age.
2.2.2. Method, Design and Procedures
184.108.40.206. Imaging Parameters
220.127.116.11. Stimuli and Presentation Parameters
- Digitized auditory segments: Four languages (Russian, English, Spanish, and Georgian) played through headphones in 30-s blocks with two alternating languages in each run. (Students wear headphones in the scanner. The sound quality is good enough to be heard over the scanner noise. We ensure that this is the case with testing of the stimuli before scanning and through post-scan interviews with subjects). In the scanning sessions with the reading task included, the auditory segments included three languages (Russian, English, Spanish).
- The subjects are told in advance only that they will be hearing samples of different languages. The voices for each language will be different (including male and female voices at an indeterminable age [i.e., no child or elderly voices will be used]) but with native pronunciation.
- The speakers recorded in the digital sound files were unknown to the subjects participating in the study. In the longitudinal study, subjects hear the same protocol across scans. However, any habituation effects are unlikely, given the large time frames between sessions. Using the same stimulus files at each visit is important for the purposes of this study so that we can be certain none of the activations observed are due to differences in the content of the stimulus.
- Participants were not excluded based on handedness, although all subjects in the longitudinal study were right-handed.
- This section of the functional scan involved only auditory comprehension. Reading comprehension, which was added during the first year to the protocol, was given at the end of the scan.
- Each 30-s audio stimulus consists of unique utterances—no repetitions of content between or among languages.
- There is a 10 s rest period following each audio segment.
- A series of questions was administered immediately after the fMRI session, including the following list:
- Did you understand all of the utterances in the languages in which you are proficient?
- Did you understand any of the utterances in the 3rd and/or 4th languages? If so, approximate how often—less than 50%, more than 50%, etc.
- Is there anything that occurred during the imaging session that may have interfered with the listening comprehension process?
- All subjects answer a set of written questions for the auditory comprehension section and for the reading section. The experimental protocol is still in use and we do not want to bias future responses. Some samples, however, are given below.
- Do the students get help with reading? With speaking?
- Does the family like animals? What kind of apartment did they live in?
- What helps children deal with their emotions?
- What was the dog’s name?
- Finally, as part of the debriefing, the participants will be interviewed on the general content of what they heard and read and asked to provide information on their thoughts and sensations during the scanning process.
2.2.3. Language Proficiency Testing
2.3. Subject Information
|Course Work||Intensive First Year||Intensive Second Year|
|Scan||Scan 1||Scan 2||Scan 3|
|Test||A2||B1 (a)||B1 (b)|
- Sept–Dec, 2011: Six contact hours per week for 13 weeks (at Duke); 20 contact hours per week for three weeks (at SPSU)
- Jan–April, 2012: 16 weeks: six contact hours per week (at Duke)
- May–June, 2012: Seven weeks, 120 contact hours total (at SPSU)
3. Analysis of fMRI Data
- English-rest: Drop in number of regions of activation and mean level of activations across regions from first through third scan.
- Russian-rest: Increase in number of regions of activation and mean level of activations from first through third scan; in some cases, individual regions of interest show a steady increase across scans, while in others, there is a slight drop between scans 2 and 3.
3.1. Regions of Interest
- Left and right Medial Temporal Gyrus (MTG) BA 21
- l/r Superior Temporal Gyrus (STG) BA 22
- l/r Middle Frontal Gyrus (MFG) BA 46
- l/r Inferior Frontal Gyrus (IFG) BA 44, 45, 47
- l/r Postcentral Gyrus (PoG) BA 3, 1, 2
- l/r Precentral Gyrus (PrG) BA four posteriorly, six anteriorly
3.2. Longitudinal Comparisons across English and Russian Conditions across Subjects
3.3. MANCOVA Analysis
3.3.1. Primary Results of the Analysis
3.3.2. Secondary Results of the Analysis
- The time effect is significant for Russian-rest; average activation levels change across the different sets of measurements.
- The time effect is not significant for English-rest; average activation levels do not change across the different sets.
- There is a significant hemisphere effect.
- The Middle Occipital Gyrus, used as an internal statistical standard, shows a lack of effect as expected.
- Different regions show variation in activation patterns.
4. Towards an Explanation of Bilaterality of Language
6. Conclusions and Future Directions
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