Converging Evidence for Differential Specialization and Plasticity of Language Systems

First published November 9, 2020.Functional specialization and plasticity are fundamental organizing principles of the brain. Since the mid-1800s, certain cognitive functions have been known to be lateralized, but the provenance and flexibility of hemispheric specialization remain open questions. Language is a uniquely human phenomenon that requires a delicate balance between neural specialization and plasticity, and language learning offers the perfect window to study these principles in the human brain. In the current study, we conducted two separate functional MRI experiments with language learners (male and female), one cross-sectional and one longitudinal, involving distinct populations and languages, and examined hemispheric lateralization and learning-dependent plasticity of the following three language systems: reading, speech comprehension, and verbal production. A multipronged analytic approach revealed a highly consistent pattern of results across the two experiments, showing (1) that in both native and non-native languages, while language production was left lateralized, lateralization for language comprehension was highly variable across individuals; and (2) that with increasing non-native language proficiency, reading and speech comprehension displayed substantial changes in hemispheric dominance, with languages tending to lateralize to opposite hemispheres, while production showed negligible change and remained left lateralized. These convergent results shed light on the long-standing debate of neural organization of language by establishing robust principles of lateralization and plasticity of the main language systems. Findings further suggest involvement of the sensorimotor systems in language lateralization and its plasticity.K.G. eceived support from “la Caixa” Foundation (ID 100010434) through the fellowship LCF/BQ/DI17/11620005 and from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant 713673. J.A.-T. was supported by Basque Government predoctoral Grant PRE_2015_1_028. M.C. was supported by project APCIN-2015-061-MultiLateral, which is funded by the Spanish Ministry of Economy and Competitiveness (MINECO; Grant FLAG-ERA JTC 2015). P.M.P.-A. was supported by MINECO Grants RYC-2014-15440 and PGC2018-093408-B-I00, and the Neuroscience Research Projects program from the Fundacion Tatiana Perez de Guzman el Bueno. The research was also supported by the Basque Government (Grant BERC 2018–2021) and the Spanish State Research Agency through the Basque Center on Cognition, Brain and Language Severo Ochoa excellence accreditation (Grant SEV-2015-0490)

What Can Glioma Patients Teach Us about Language (Re)Organization in the Bilingual Brain: Evidence from fMRI and MEG

Published: 25 May 2021Recent evidence suggests that the presence of brain tumors (e.g., low-grade gliomas) triggers language reorganization. Neuroplasticity mechanisms called into play can transfer linguistic functions from damaged to healthy areas unaffected by the tumor. This phenomenon has been reported in monolingual patients, but much less is known about the neuroplasticity of language in the bilingual brain. A central question is whether processing a first or second language involves the same or different cortical territories and whether damage results in diverse recovery patterns depending on the language involved. This question becomes critical for preserving language areas in bilingual brain-tumor patients to prevent involuntary pathological symptoms following resection. While most studies have focused on intraoperative mapping, here, we go further, reporting clinical cases for five bilingual patients tested before and after tumor resection, using a novel multimethod approach merging neuroimaging information from fMRI and MEG to map the longitudinal reshaping of the language system. Here, we present four main findings. First, all patients preserved linguistic function in both languages after surgery, suggesting that the surgical intervention with intraoperative language mapping was successful in preserving cortical and subcortical structures necessary for brain plasticity at the functional level. Second, we found reorganization of the language network after tumor resection in both languages, mainly reflected by a shift of activity to right hemisphere nodes and the recruitment of ipsilesional left nodes. Third, we found that this reorganization varied according to the language involved, indicating that L1 and L2 follow different reshaping patterns after surgery. Fourth, oscillatory longitudinal effects were correlated with BOLD laterality changes in superior parietal and middle frontal areas. These findings may reflect that neuroplasticity impacts on the compensatory involvement of executive control regions, supporting the allocation of cognitive resources as a consequence of increased attentional demands. Furthermore, these results hint at the complementary role of this neuroimaging approach in language mapping, with fMRI offering excellent spatial localization and MEG providing optimal spectrotemporal resolutionThis research was supported by the Ikerbasque Foundation; by the Basque Government through the BERC 2018 2021 program; by the Spanish State Research Agency through BCBL Severo Ochoa excellence accreditation SEV 2015 0490; by the Fundación Científica AECC (FCAECC) through the project PROYE20005CARR; by a Juan de la Cierva Fellowship to LA (IJCI 2017 31373); and by the Spanish Ministry of Economy and Competitiveness through the Plan Nacional RTI2018 096216 A I00 (MEGLIOMA) to LA and RTI2018 093547 B I00 (LANGCONN) to MC and IQ

Neural Plasticity of Language Systems: evidence from fMRI experiments with adult language learners

216 p.Functional specialisation and plasticity are fundamental organising principles of the brain. Language is a uniquely human phenomenon that requires a delicate balance between neural specialisation and plasticity, and language learning offers the perfect window to study these principles in the human brain. Though the human brain exhibits a remarkable ability to support a variety of languages that may be acquired at different points in the life span, the capacity for neural reorganisation decreases with age. Further, language is a complex construct involving linguistic as well as visual, auditory, and motor processes. The current doctoral thesis asked two main questions: (1) Do large-scale functional changes accompany language learning in adulthood? and (2) Are these neural changes similar across different language systems such as reading, speech comprehension, and verbal production? These questions were investigated in three fMRI experiments with adult language learners. In Experiments I and II, comprehension and production were examined in 30-to-60-year-old intermediate and advanced language learners and functional learning-related changes in each modality were comprehensively characterised. In Experiment III, hemispheric lateralisation of reading, speech comprehension, and verbal production were compared and contrasted, and the analyses were extended to a second longitudinal study with a contrasting participant sample. Robust evidence was found for significant functional plasticity well into adulthood, and results showed that different language systems exhibited different patterns of hemispheric specialisation and plasticity. The results have theoretical and practical implications for our understanding of fundamental principles of neural organisation of language, language learning in healthy populations, and language testing and recovery in patients

The Adult Learner: Nature or Nurture?: A Case study of Teacher Educators and Teacher Learners

Adult learning is very broadly viewed in the literature. The wide-ranging gamut of views, include those that interpret adult learning not dissimilarly to child learning, all the way through to theorists that propose a separate set of considerations for adult learners. When it comes to learning, pedagogy was traditionally associated with child learners and andragogy was born from the need to find a separate niche for the adult learner. As such, pedagogy and andragogy may be positioned opposite to one another—as one pertains to the needs; characteristics; and, behaviours of the child, and the other of the adult learner. These chronological apportionments of pedagogy and andragogy do not properly address the influence of context on the learner. Context is multifaceted, and includes internal elements such as feelings; thoughts; and, behaviours—which are, the learner’s very nature. Further to this, context for the adult learner is external, and encompasses elements such as the learning environment; educators; and, work-place pressures and requirements. Understanding the contextual forces on adult learning, calls into question whether all adult learners function within an andragogical framework. A qualitative case study approach was used in the setting of teacher professional learning for primary science education in NSW, Australia, to garner a deeper understanding of adult learning. Participants, both teacher educators and teacher learners, provided insights into their learning journey. This study selected two external influences on the adult learner in this setting; the introduction of the NESA K–6 Science and Technology Syllabus (2012), which was the primary science education curriculum for NSW; and, the technological pedagogical content knowledge (TPACK) framework. In NSW, NESA is the independent statutory authority responsible for curriculum, assessment, teaching standards and school settings. Alongside the two external influences, the internal influence of teacher self-efficacy was used to better understand the adult learner. Teacher participant voice from interview gave rise to findings that illuminated the plasticity of the adult learner, moving between pedagogical and andragogical learner traits at various points in their learning journey, as well as transitioning in expertise. Adult learners were most successful in this study’s learning context when there was interplay between their internal learner forces (ILFs), their nature; and, external learner forces (ELFs), the nurture or environment. These findings may have potential for transferability to analogous professional learning contexts of the adult learner

The nature of the interactions between verbal working memory and long-term memory knowledge: a behavioral and neuroimaging investigation

The research conducted in this PhD Thesis aimed to determine the nature of the interactions between verbal working memory (WM) and long-term memory (LTM) knowledge by investigating the cognitive and neural aspects of the potential overlap between the two systems. This question was addressed through three experimental studies employing behavioral paradigms and advanced neuroimaging techniques, including the investigation of the impact of syntactic knowledge on verbal WM performance (Study 1), an fMRI investigation of the neural substrates associated with long-term semantic knowledge and maintenance of semantic information in verbal WM (Study 2), and an fMRI investigation of the language learning-related changes in the cortices that support verbal WM (Study 3). Our findings demonstrate at least partial overlap between verbal WM and long-term linguistic knowledge, characterized by dynamic and flexible interactions. Overall, these results support hybrid, partially emergent language-based models of WM, while emphasizing that although verbal WM and LTM knowledge interact, verbal WM performance extends beyond the simple activation of linguistic knowledge. Verbal WM interacts dynamically with other cognitive processes, and LTM knowledge rather intervenes in a flexible manner in verbal WM. This thesis highlights the importance of adopting an integrative approach that encompasses all language representations, takes into account potential interactions between verbal WM and episodic memory processes, and reflects the flexible and adaptive nature of long-term linguistic knowledge activation in verbal WM

Functional plasticity associated with language learning in adults

Available online 20 July 2019.Learning a new language in adulthood is increasingly common and among the most difficult tasks attempted by adults. Adult language learners thus offer an excellent window into the nature of learning-dependent plasticity. The present functional magnetic resonance imaging (fMRI) study was aimed at characterising functional neuroplasticity in adults at different stages of learning a second language (L2). To this end, a total of 34 adults, either intermediate or advanced L2 learners, underwent MRI scanning while performing a semantic judgement task with print and speech stimuli. Three separate analytical approaches were used to comprehensively map neural differences: print-speech convergence, L1-L2 similarity, and functional connectivity with language control regions. Results revealed that (i) print-speech convergence was not affected by L2 proficiency level, (ii) L1-L2 similarity was significantly higher in intermediate than in advanced L2 learners, and (iii) functional coupling of language and language control areas was higher in the advanced relative to the intermediate group during reading comprehension. The results point to significant functional differences between intermediate and advanced language learners, indicating that, even well into adulthood, increasing L2 proficiency modulates the functional similarity between L1 and L2 and the connectivity between language comprehension and language control regions, particularly in reading comprehension.Kshipra Gurunandan received support from “la Caixa” Foundation (ID 100010434) through the fellowship LCF/BQ/DI17/11620005 and the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 713673. Manuel Carreiras was supported by project APCIN-2015-061-MultiLateral funded by the Spanish Ministry of Economy and Competitiveness (MINECO) [FLAG-ERA JTC 2015]. Pedro M. Paz-Alonso was supported by grants from MINECO RYC-2014-15440, PGC2018-093408-B-I00], the Adinberri programme from the Diputaci on Foral de Gipuzkoa [OF301/2018], and the Neuroscience Research Projects programme from the Fundaci on Tatiana P erez de Guzm an el Bueno. The research was also supported by funding from the Basque Government [BERC 2018–2021] and the Spanish State Research Agency through BCBL Severo Ochoa excellence accreditation [SEV-2015-0490]