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Volume 26, Issue 2 (summer 2024)
Advances in Cognitive Sciences 2024, 26(2): 31-46 |
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Research code: 1401
Ethics code: IR.IUMS.REC.1398.465
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Meykadeh S, Sommer W. The auditory sentence processing and the planum temporale: Evidence from functional magnetic resonance mapping in bilinguals. Advances in Cognitive Sciences 2024; 26 (2) :31-46
URL: http://icssjournal.ir/article-1-1641-en.html
URL: http://icssjournal.ir/article-1-1641-en.html
1- PhD, Linguistics Department, Tarbiat Modares University, Tehran, Iran
2- Professor, Psychology Department, Humboldt University of Berlin, Berlin, Germany
2- Professor, Psychology Department, Humboldt University of Berlin, Berlin, Germany
Abstract: (854 Views)
Introduction
To our knowledge, no study has yet used the auditory paradigm to investigate PT activation during L1-L2 sentence processing. Employing this experimental design is critical to our understanding of target/non-target language activation. Moreover, research in this area has mainly been limited to the neuroanatomical or pathological studies with little attention to bilinguals. Consequently, the extent to which the bilateral PTs are activated during simultaneous L1-L2 processing needs to be clarified. The present study aims to explore these critical issues.
To address this study’s goal, the discussion critical revolve around the following questions:
Q1. Do the left and right PT act differently for the auditory sentence processing?
Q2. Are L1 and L2 processed differently in the PL?
Methods
This study recruited healthy and young bilingual adults through social media via advertisements on top universities in Tehran, Iran. In total, forty-one subjects participated in the experiment. Five subjects were excluded due to technical problems. The final sample consisted of thirty-six (21 female, all right-handed). All participants were native speakers of Turkish who had learned Persian as L2 at the age of seven when entering school. Participants underwent an fMRI scan and completed an auditory grammaticality judgment task in the scanner. During the 21.5-min fMRI scan, participants were required to judge each sentence for grammatical correctness by pressing the button of a left (ungrammatical) or right (grammatical) response grip with the thumb while minimizing head movements. The task included four alternating rest and auditory sentence blocks. Each auditory sentence block had 32 runs and was bookended by 30-second rest periods where no stimuli were presented, allowing for hemodynamic baseline data collection. Correct and violated sentences were randomly intermixed within each block, but language blocks alternated in a fixed sequence. In total, 128 spoken sentences (50% in L1 and 50% in L2, with 50% violation per language) were used to assess syntactic processing in bilinguals. Images were acquired with a Siemens Prisma 3-Tesla scanner at NBML. The fMRI images were collected using an echo-planar imaging (EPI) sequence with a 20-channel head coil consisting of 430 volumes and 45 axial slices per volume (repetition time (TR)=3000 ms, echo time (TE)=30 ms, flip angle=90◦, matrix size=64×64, slice thickness=3 mm, field of view (FOV)=192 mm2, voxel size=3×3×3 mm3). Moreover, the high-resolution T1-weighted structural images were collected through a magnetization-prepared rapid gradient-echo (MPRAGE) sequence (TR=1800 ms, TE=3.53 ms, flip angle=7◦, matrix size=256×256, slice thickness=1 mm, FOV=256 mm2, voxel size=1×1×1 mm3, duration=5-min). The anatomical MPRAGE volumes were pre-processed following the brain extraction and used as anatomical references in the functional image processing co-registration steps using FEAT in FSL. The fMRI analyses were performed according to a standard pipeline comprising the following steps: motion correction and realignment, slice-timing correction, segmentation and normalization to the standard MNI template and spatial smoothing (6 mm full-width at half-maximum isotropic Gaussian), temporal filtering (with sigma=50.0 s), and exploratory ICA-based data analysis. The general linear model (GLM) was used to construct the statistical model on the BOLD response to perform the first-level analysis. Z (Gaussianised T/F) statistic images were thresholded using clusters determined by Z>3.1 and a (corrected) cluster significance threshold of P<0.05. A whole-brain analysis was performed to detect the mechanisms underlying syntactic processing in the bilateral PT. Then, PSC was extracted as an intensity measure in this region per participant according to the Harvard-Oxford Atlas implemented in FSL. All statistical analyses were conducted in IBM SPSS Statistics V26.
Results
Whole-Brain Results of Brain Activation
Figure 1A visualizes the location of the PT. Figure 1B exhibits the patterns of whole-brain activation during the presentation of corrected and violated stimuli in L1 and L2 for each hemisphere. Greater left-hemispheric activation is detectable for the region of the PT (white circles) when comparing the left and right columns.
ROI-based Results
The results are depicted in Figure 2. The main factor of Grammaticality yielded a significant effect (F (1, 35)=53.296, P<0.001,
Finally, the Grammaticality×Language×Hemisphere interaction (F (1, 35)=7.961, P=0.008,
Conclusion
The current findings are essential in several ways. First, the present findings indicate a substantial overlap of the neuronal correlates for L1 and L2 in the PT, confirming our participants’ L2 high-proficiency. Second, our results support the contribution of the left PT as a computational interface in sentence processing. Third, the sensitivity of the right PT to the present auditory stimuli confirms its role in stimulus-driven auditory attention. Fourth, the higher activity of L1-ungrammatical stimuli as compared to L2-ungrammatical stimuli in the left hemisphere indicates that current bilinguals have chosen L1 (Turkish) as their base language, leading to more RT switch cost for L1 than L2, as well as increased cognitive control to reactivate L1 after L2 production. Fifth, L1-L2 similarities at the sentence level can facilitate the L2 processing.
Ethical Considerations
Compliance with ethical guidelines
The Ethics Committee of Iran University of Medical Sciences has approved the current research under the code IR.IUMS.REC.1398.465. We strictly adhered to all ethical guidelines, including clearly explaining the research objectives to participants, ensuring their freedom to join or withdraw from the study at any time, obtaining written consent, maintaining the confidentiality of participants’ information, and compensating them for their time.
Authors’ contributions
This article is part of the first author’s PhD dissertation at Tarbiat Modares University of Tehran. The first author conceptualized the study, collected and analyzed the data, designed the task, wrote the manuscript, and provided valuable laboratory resources. The second author contributed to the planning of the work, designed the task, and supervised data analysis. Both authors approved the submitted version.
Funding
The Cognitive Sciences and Technologies Council supported this study under Grant [number 7401] awarded to the first author. This research was also made possible by a doctoral dissertation grant from the Department of Linguistics, Tarbiat Modares University, a scholarship fund (PhD Visiting Scholar Program) from the Iranian Ministry of Science, Research and Technology, and a research grant from Iran High-tech Laboratory Network.
Acknowledgments
The authors wish to express their appreciation to the participants.
Conflict of interest
Authors have no conflict of interest to declare.
To our knowledge, no study has yet used the auditory paradigm to investigate PT activation during L1-L2 sentence processing. Employing this experimental design is critical to our understanding of target/non-target language activation. Moreover, research in this area has mainly been limited to the neuroanatomical or pathological studies with little attention to bilinguals. Consequently, the extent to which the bilateral PTs are activated during simultaneous L1-L2 processing needs to be clarified. The present study aims to explore these critical issues.
To address this study’s goal, the discussion critical revolve around the following questions:
Q1. Do the left and right PT act differently for the auditory sentence processing?
Q2. Are L1 and L2 processed differently in the PL?
Methods
This study recruited healthy and young bilingual adults through social media via advertisements on top universities in Tehran, Iran. In total, forty-one subjects participated in the experiment. Five subjects were excluded due to technical problems. The final sample consisted of thirty-six (21 female, all right-handed). All participants were native speakers of Turkish who had learned Persian as L2 at the age of seven when entering school. Participants underwent an fMRI scan and completed an auditory grammaticality judgment task in the scanner. During the 21.5-min fMRI scan, participants were required to judge each sentence for grammatical correctness by pressing the button of a left (ungrammatical) or right (grammatical) response grip with the thumb while minimizing head movements. The task included four alternating rest and auditory sentence blocks. Each auditory sentence block had 32 runs and was bookended by 30-second rest periods where no stimuli were presented, allowing for hemodynamic baseline data collection. Correct and violated sentences were randomly intermixed within each block, but language blocks alternated in a fixed sequence. In total, 128 spoken sentences (50% in L1 and 50% in L2, with 50% violation per language) were used to assess syntactic processing in bilinguals. Images were acquired with a Siemens Prisma 3-Tesla scanner at NBML. The fMRI images were collected using an echo-planar imaging (EPI) sequence with a 20-channel head coil consisting of 430 volumes and 45 axial slices per volume (repetition time (TR)=3000 ms, echo time (TE)=30 ms, flip angle=90◦, matrix size=64×64, slice thickness=3 mm, field of view (FOV)=192 mm2, voxel size=3×3×3 mm3). Moreover, the high-resolution T1-weighted structural images were collected through a magnetization-prepared rapid gradient-echo (MPRAGE) sequence (TR=1800 ms, TE=3.53 ms, flip angle=7◦, matrix size=256×256, slice thickness=1 mm, FOV=256 mm2, voxel size=1×1×1 mm3, duration=5-min). The anatomical MPRAGE volumes were pre-processed following the brain extraction and used as anatomical references in the functional image processing co-registration steps using FEAT in FSL. The fMRI analyses were performed according to a standard pipeline comprising the following steps: motion correction and realignment, slice-timing correction, segmentation and normalization to the standard MNI template and spatial smoothing (6 mm full-width at half-maximum isotropic Gaussian), temporal filtering (with sigma=50.0 s), and exploratory ICA-based data analysis. The general linear model (GLM) was used to construct the statistical model on the BOLD response to perform the first-level analysis. Z (Gaussianised T/F) statistic images were thresholded using clusters determined by Z>3.1 and a (corrected) cluster significance threshold of P<0.05. A whole-brain analysis was performed to detect the mechanisms underlying syntactic processing in the bilateral PT. Then, PSC was extracted as an intensity measure in this region per participant according to the Harvard-Oxford Atlas implemented in FSL. All statistical analyses were conducted in IBM SPSS Statistics V26.
Results
Whole-Brain Results of Brain Activation
Figure 1A visualizes the location of the PT. Figure 1B exhibits the patterns of whole-brain activation during the presentation of corrected and violated stimuli in L1 and L2 for each hemisphere. Greater left-hemispheric activation is detectable for the region of the PT (white circles) when comparing the left and right columns.
ROI-based Results
The results are depicted in Figure 2. The main factor of Grammaticality yielded a significant effect (F (1, 35)=53.296, P<0.001,
Finally, the Grammaticality×Language×Hemisphere interaction (F (1, 35)=7.961, P=0.008,
Conclusion
The current findings are essential in several ways. First, the present findings indicate a substantial overlap of the neuronal correlates for L1 and L2 in the PT, confirming our participants’ L2 high-proficiency. Second, our results support the contribution of the left PT as a computational interface in sentence processing. Third, the sensitivity of the right PT to the present auditory stimuli confirms its role in stimulus-driven auditory attention. Fourth, the higher activity of L1-ungrammatical stimuli as compared to L2-ungrammatical stimuli in the left hemisphere indicates that current bilinguals have chosen L1 (Turkish) as their base language, leading to more RT switch cost for L1 than L2, as well as increased cognitive control to reactivate L1 after L2 production. Fifth, L1-L2 similarities at the sentence level can facilitate the L2 processing.
Ethical Considerations
Compliance with ethical guidelines
The Ethics Committee of Iran University of Medical Sciences has approved the current research under the code IR.IUMS.REC.1398.465. We strictly adhered to all ethical guidelines, including clearly explaining the research objectives to participants, ensuring their freedom to join or withdraw from the study at any time, obtaining written consent, maintaining the confidentiality of participants’ information, and compensating them for their time.
Authors’ contributions
This article is part of the first author’s PhD dissertation at Tarbiat Modares University of Tehran. The first author conceptualized the study, collected and analyzed the data, designed the task, wrote the manuscript, and provided valuable laboratory resources. The second author contributed to the planning of the work, designed the task, and supervised data analysis. Both authors approved the submitted version.
Funding
The Cognitive Sciences and Technologies Council supported this study under Grant [number 7401] awarded to the first author. This research was also made possible by a doctoral dissertation grant from the Department of Linguistics, Tarbiat Modares University, a scholarship fund (PhD Visiting Scholar Program) from the Iranian Ministry of Science, Research and Technology, and a research grant from Iran High-tech Laboratory Network.
Acknowledgments
The authors wish to express their appreciation to the participants.
Conflict of interest
Authors have no conflict of interest to declare.
Keywords: Balanced bilinguals, Auditory sentence processing, Planum temporale, Functional magnetic resonance imaging
Type of Study: Research |
Received: 2023/12/2 | Accepted: 2024/08/18 | Published: 2024/11/3
Received: 2023/12/2 | Accepted: 2024/08/18 | Published: 2024/11/3
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