Multifactorial approaches to study bilingualism in the aging population: Past, present, future

A better understanding and more reliable classification of bilinguals has been progressively achieved through the fine-tuning methodology and simultaneously optimizing the measurement tools. However, the current understanding is far from generalization to a larger population varying in different measures of bilingualism—L2 Age of acquisition (L2 AOA), L2 usage and exposure, and L2 proficiency. More recent studies have highlighted the importance of modeling bilingualism as a continuous variable. An in-depth look at the role of bilingualism, comparing groups, may be considered a reductionist approach, i.e., grouping based on one measure of bilingualism (e.g., L2 AOA) may not account for variability in other measures of bilingualism (L2 exposure, L2 use or L2 proficiency, amongst others) within and between groups. Similarly, a multifactorial dimension is associated with cognitive performance, where not all domains of cognition and subcomponents are equally influenced by bilingualism. In addition, socio-cultural and demographical factors may add another dimension to the impact of bilingualism on cognitive performance, especially in older adults. Nevertheless, not many studies have controlled or used the multiple socio-cultural and demographical factors as a covariate to understand the role of different aspects of bilingualism that may influence cognitive performance differently. Such an approach would fail to generalize the research findings to a larger group of bilinguals. In the present review paper, we illustrate that considering a multifactorial approach to different dimensions of bilingual study may lead to a better understanding of the role of bilingualism on cognitive performance. With the evolution of various fine-tuned methodological approaches, there is a greater need to study variability in bilingual profiles that can help generalize the result universally

O PROCESSAMENTO DE NARRATIVAS EM SEGUNDA LÍNGUA: UM ESTUDO COM fNIRS

! is article presents the results of a study which investigated theperformance of native speakers of English (L1) when reading texts in French(L2), language in which they had intermediate pro" ciency. ! e study investi-gated, in relation to behavioral performance, these readers’ accuracy and re-sponse times when processing the text at three di# erent levels (the macro- andthe micro-structure and the situational model), whereas, with respect to brainactivity, the study analyzed the participation of the two cerebral hemispheresin processing the three levels mentioned above, using the fNIRS (functionalNear-Infrared Spectroscopy) neuroimaging tool. ! e behavioral results showstatistically signi" cant di# erences between the two groups. ! e neuroimag-ing results indicate a statistically signi" cant participation of the two regionsof interest in temporal areas of the right hemisphere during processing at themacro-structure, as well as of temporal and frontal regions in the le$ hemi-sphere in comprehension at the microstructure

Interference control at the response level: Functional networks reveal higher efficiency in the bilingual brain

RÉSUMÉ: The bilingual advantage in interference control tasks has been studied with the Simon task, among others. The mixed evidence from the existing studies has led to contradictions in the literature regarding the bilingual advantage. Moreover, fMRI evidence on the neural basis of interference control mechanisms with the Simon task is limited. Previous work by our team showed that equivalent performance on the Simon task was associated with different activation maps in elderly bilinguals and monolinguals. This study aims to pro- vide a more in-depth perspective on the neural bases of performance on the Simon task in elderly bilinguals and monolinguals, by adopting a network perspective for the functional connectivity analysis. A node-by-node analysis led to the identification of the specific topology that characterized the bilingual and monolingual functional networks and the degree of connectivity between each node across groups. Results showed greater con- nectivity in bilinguals in the inferior temporal sulcus, which plays a role in visuospatial processing. On the other hand, in monolinguals, brain areas involved in visual, motor, executive functions and interference control were more connected to resolve the same task. In other words, in comparison to the monolingual brain, the bilingual brain resolves visuospatial interference economically, by allocating fewer and more clustered regions. These results demonstrate a larger global efficiency in task performance in bilinguals as compared to monolinguals. Also, the provided evidence filters out the task-specific so- called bilingual advantage discussed in the literature and posits that bilinguals are stra- tegically more efficient in a given performance than monolinguals, thus enhancing our understanding of successful aging

A Network Analysis Approach to fMRI Condition-Specific Functional Connectivity

In this work we focus on examination and comparison of whole-brain functional connectivity patterns measured with fMRI across experimental conditions. Direct examination and comparison of condition-specific matrices is challenging due to the large number of elements in a connectivity matrix. We present a framework that uses network analysis to describe condition-specific functional connectivity. Treating the brain as a complex system in terms of a network, we extract the most relevant connectivity information by partitioning each network into clusters representing functionally connected brain regions. Extracted clusters are used as features for predicting experimental condition in a new data set. The approach is illustrated on fMRI data examining functional connectivity patterns during processing of abstract and concrete concepts. Topological (brain regions) and functional (level of connectivity and information flow) systematic differences in the ROI-based functional networks were identified across participants for concrete and abstract concepts. These differences were sufficient for classification of previously unseen connectivity matrices as abstract or concrete based on training data derived from other people

The Neural and Behavioral Correlates of Anomia Recovery following Personalized Observation, Execution, and Mental Imagery Therapy: A Proof of Concept

The impact of sensorimotor strategies on aphasia recovery has rarely been explored. This paper reports on the efficacy of personalized observation, execution, and mental imagery (POEM) therapy, a new approach designed to integrate sensorimotor and language-based strategies to treat verb anomia, a frequent aphasia sign. Two participants with verb anomia were followed up in a pre-/posttherapy fMRI study. POEM was administered in a massed stimulation schedule, with personalized stimuli, resulting in significant improvement in both participants, with both trained and untrained items. Given that the latter finding is rarely reported in the literature, the evidence suggests that POEM favors the implementation of a word retrieval strategy that can be integrated and generalized. Changes in fMRI patterns following POEM reflect a reduction in the number of recruited areas supporting naming and the recruitment of brain areas that belong to the language and mirror neuron systems. The data provide evidence on the efficacy of POEM for verb anomia, while pointing to the added value of combined language and sensorimotor strategies for recovery from verb anomia, contributing to the consolidation of a word retrieval strategy that can be better generalized to untrained words. Future studies with a larger sample of participants are required to further explore this avenue

Neuroimaging of the bilingual brain: evidence and research methodology = Neuroimagem do cérebro bilíngüe: evidências e metodologia de pesquisa = Neuroimagen del cerebro bilíngüe: evidencia e investigación metodológica

Atualmente mais da metade da população mundial é bilíngüe, sendo o estudo do processamento lingüístico e de seus correlatos cerebrais em indivíduos bilíngües um tópico relevante e inovador na recente área da neuropsicolingüística. Este artigo tem dois objetivos: 1) discutir alguns aspectos metodológicos relacionados ao desenvolvimento de investigações com técnicas de neuroimagem sobre o processamento da linguagem no cérebro bilíngüe e 2) revisar evidências de neuroimagem sobre o processamento lingüístico considerando fatores individuais que têm caracterizado a literatura acerca do bilingüismo, por seu importante papel na representação cerebral bilíngüe da linguagem. Muitos estudos têm mostrado dados sobre a relação entre idade de aquisição, nível de proficiência, idade cronológica, uso de linguagem e forma de exposição às línguas na organização da linguagem no cérebro bilíngüe. A grande variabilidade de métodos de investigação e um controle metodológico nem sempre criterioso tem tornado difícil a generalização de conclusões sobre uma circuitaria cerebral da linguagem em bilíngües. A presente discussão deve contribuir para o debate dos fundamentos teóricos e metodológicos da organização neurofuncional da linguagem no cérebro bilíngü

Maladaptive Plasticity in Aphasia: Brain Activation Maps Underlying Verb Retrieval Errors

Anomia, or impaired word retrieval, is the most widespread symptom of aphasia, an acquired language impairment secondary to brain damage. In the last decades, functional neuroimaging techniques have enabled studying the neural basis underlying anomia and its recovery. The present study aimed to explore maladaptive plasticity in persistent verb anomia, in three male participants with chronic nonfluent aphasia. Brain activation maps associated with semantic verb paraphasia occurring within an oral picture-naming task were identified with an event-related fMRI paradigm. These maps were compared with those obtained in our previous study examining adaptive plasticity (i.e., successful verb naming) in the same participants. The results show that activation patterns related to semantic verb paraphasia and successful verb naming comprise a number of common areas, contributing to both maladaptive and adaptive neuroplasticity mechanisms. This finding suggests that the segregation of brain areas provides only a partial view of the neural basis of verb anomia and successful verb naming. Therefore, it indicates the importance of network approaches which may better capture the complexity of maladaptive and adaptive neuroplasticity mechanisms in anomia recovery