Hemispheric Lateralization of Visuospatial Attention Is Independent of Language Production on Right-Handers: Evidence From Functional Near-Infrared Spectroscopy

It is well-established that visuospatial attention is mainly lateralized to the right hemisphere, whereas language production is mainly left-lateralized. However, there is a significant controversy regarding how these two kinds of lateralization interact with each other. The present research used functional near-infrared spectroscopy (fNIRS) to examine whether visuospatial attention is indeed right-lateralized, whereas language production is left-lateralized, and more importantly, whether the extent of lateralization in the visuospatial task is correlated with that in the task involving language. Specifically, fifty-two healthy right-handed participants participated in this study. Multiple-channel fNIRS technique was utilized to record the cerebral hemodynamic changes when participants were engaged in naming objects depicted in pictures (the picture naming task) or judging whether a presented line was bisected correctly (the landmark task). The degree of hemispheric lateralization was quantified according to the activation difference between the left and right hemispheres. We found that the picture-naming task predominantly activated the inferior frontal gyrus (IFG) of the left hemisphere. In contrast, the landmark task predominantly activated the inferior parietal sulcus (IPS) and superior parietal lobule (SPL) of the right hemisphere. The quantitative calculation of the laterality index also showed a left-lateralized distribution for the picture-naming task and a right-lateralized distribution for the landmark task. Intriguingly, the correlation analysis revealed no significant correlation between the laterality indices of these two tasks. Our findings support the independent hypothesis, suggesting that different cognitive tasks may engender lateralized processing in the brain, but these lateralized activities may be independent of each other. Meanwhile, we stress the importance of handedness in understanding the relationship between functional asymmetries. Methodologically, we demonstrated the effectiveness of using the multichannel fNIRS technique to investigate the hemispheric specialization of different cognitive tasks and their lateralization relations between different tasks. Our findings and methods may have important implications for future research to explore lateralization-related issues in individuals with neural pathologies.

Oscillatory dynamics underlying noun and verb production in highly proficient bilinguals

Words representing objects (nouns) and words representing actions (verbs) are essential components of speech across languages. While there is evidence regarding the organizational principles governing neural representation of nouns and verbs in monolingual speakers, little is known about how this knowledge is represented in the bilingual brain. To address this gap, we recorded neuromagnetic signals while highly proficient Spanish–Basque bilinguals performed a picture-naming task and tracked the brain oscillatory dynamics underlying this process. We found theta (4–8 Hz) power increases and alpha–beta (8–25 Hz) power decreases irrespectively of the category and language at use in a time window classically associated to the controlled retrieval of lexico-semantic information. When comparing nouns and verbs within each language, we found theta power increases for verbs as compared to nouns in bilateral visual cortices and cognitive control areas including the left SMA and right middle temporal gyrus. In addition, stronger alpha–beta power decreases were observed for nouns as compared to verbs in visual cortices and semantic-related regions such as the left anterior temporal lobe and right premotor cortex. No differences were observed between categories across languages. Overall, our results suggest that noun and verb processing recruit partially different networks during speech production but that these category-based representations are similarly processed in the bilingual brain.

Sequential bilingual heritage children's L1 attrition in lexical retrieval: Age of acquisition versus language experience

This study investigated the unresolved issue of potential sources of heritage language attrition. To test contributing effects of three learner variables – age of second language acquisition, length of residence, and language input – on heritage children's lexical retrieval accuracy and speed, we conducted a real-time word naming task with 68 children (age 11–14 years) living in South Korea who spoke either Chinese or Russian as a heritage language. Results of regression analyses showed that the participants were less accurate and slower in naming target words in their heritage language as their length of residence in Korea and the amount of Korean input increased. The age of Korean acquisition did not significantly influence their performance. These findings support the claim that heritage speakers’ language experience is a more reliable predictor of first language attrition than age of acquisition. We discuss these findings in light of different approaches to explaining language attrition.

Semantic Priming in Monolingual Russian and Bilingual Russian (L1)-English (L2) Speakers in a Single Word Naming Task

Identifying and exploring factors that influence bilingual language processing has been the topic of much psycholinguistic research. Semantic priming is typically used to examine semantic processing and refers to the phenomenon in which semantically related items (doctor-nurse) are processed faster and more accurately than semantically unrelated items (doctor-butter). The aim of the chapter is to address two key questions: 1) how the two languages of a bilingual are organised or stored and 2) how the two languages are processed. A review of the literature shows that there are currently no theoretical frameworks that explain Russian monolingual or Russian (L1)-English (L2) bilingual storage or processing. Monolingual Russian speakers and bilingual Russian (L1)-English (L2) speaking university students were asked to name target words under related or unrelated conditions. The results show that the magnitude of the semantic priming effect was determined by L2 proficiency. The implications for these findings is discussed within the current bilingual theoretical models.

Internal and external factors contributing to variability in consonant accuracy of Arabic–French simultaneous bilingual children

This study aims to describe the relationships between child-internal and child-external factors and the consonant accuracy of bilingual children. More specifically, the study looks at internal factors: expressive and receptive vocabulary, and external factors: language exposure and language status, of a group of 4-year-old bilingual Arabic–French children. We measured the consonant accuracy of the children by the percentage of correct consonants in a Picture-Naming Task and a Non-Word Repetition Task in each language. The results suggest a significant relationship between vocabulary and consonant accuracy. A cross-language correlation was observed between the expressive vocabulary level of the majority language (French) and the consonant accuracy of the minority language (Arabic). Also, a significant correlation was found between Arabic language exposure and Arabic consonant accuracy. Finally, consonant accuracy was significantly higher in French tasks than in Arabic, despite the individual differences of the children.

A Data-Based Approach for Selecting Pre- and Intra-Operative Language Mapping Tasks

Background: Pre- and intra-operative language mapping in neurosurgery patients frequently involves an object naming task. The choice of the optimal object naming paradigm remains challenging due to lack of normative data and standardization in mapping practices. The aim of this study was to identify object naming paradigms that robustly and consistently activate classical language regions and could therefore be used to improve the sensitivity of language mapping in brain tumor and epilepsy patients.Methods: Functional magnetic resonance imaging (fMRI) data from two independent groups of healthy controls (total = 79) were used to generate threshold-weighted voxel-based consistency maps. This novel approach allowed us to compare inter-subject consistency of activation for naming single objects in the visual and auditory modality and naming two objects in a phrase or a sentence.Results: We found that the consistency of activation in language regions was greater for naming two objects per picture than one object per picture, even when controlling for the number of names produced in 5 s.Conclusion: More consistent activation in language areas for naming two objects compared to one object suggests that two-object naming tasks may be more suitable for delimiting language eloquent regions with pre- and intra-operative language testing. More broadly, we propose that the functional specificity of brain mapping paradigms for a whole range of different linguistic and non-linguistic functions could be enhanced by referring to databased models of inter-subject consistency and variability in typical and atypical brain responses.

Language Assessment in Multilingualism and Awake Neurosurgery

Multilingualism has become a worldwide phenomenon that poses critical issues about the language assessment in patients undergoing awake neurosurgery in eloquent brain areas. The accuracy and sensitivity of multilingual perioperative language assessment procedures is crucial for a number of reasons: they should be appropriate to detect deficits in each of the languages spoken by the patient; they should be suitable to identify language-specific cortical regions; they should ensure that each of the languages of a multilingual patient is tested at an adequate and comparable level of difficulty. In clinical practice, a patient-tailored approach is generally preferred. This is a necessary compromise since it is impossible to predict all the possible language combinations spoken by individuals and thus the availability of standardized testing batteries is a potentially unattainable goal. On the other hand, this leads to high inconsistency in how different neurosurgical teams manage the linguistic features that determine similarity or distance between the languages spoken by the patient and that may constrain the neuroanatomical substrate of each language. The manuscript reviews the perioperative language assessment methodologies adopted in awake surgery studies on multilingual patients with brain tumor published from 1991 to 2021 and addresses the following issues: (1) The language selected for the general neuropsychological assessment of the patient. (2) The procedures adopted to assess the dimensions that may constrain language organization in multilingual speakers: age and type of acquisition, exposure, proficiency, and use of the different languages. (3) The type of preoperative language assessment used for all the languages spoken by the patient. (4) The linguistic tasks selected in the intraoperative setting. The reviewed data show a great heterogeneity in the perioperative clinical workup with multilingual patients. The only exception is the task used during language mapping, as the picture naming task is highly preferred. The review highlights that an objective and accurate description of both the linguistic profile of multilingual patients and the specific properties of the languages under scrutiny can profitably support clinical management and decision making in multilingual awake neurosurgery settings.

Comparing the Informativeness of Single-Word Samples and Connected Speech Samples in Assessing Speech Sound Disorders

Purpose Speech-language pathologists (SLPs) are faced with the challenge of quickly and accurately identifying children who present with speech sound disorders (SSD) compared to typically developing (TD) children. The goal of this study was to compare the clinical relevance of two speech sampling methods (single-word vs. connected speech samples) in how sensitive they are in detecting atypical speech sound development in children, and to know whether the information obtained from single-word samples is representative enough of children's overall speech sound performance. Method We compared the speech sound performance of 37 preschool children with SSD ( M age = 4;11 years) and 37 age-sex-matched typically developing children ( M age = 5;0 years) by eliciting their speech in two ways: (a) a picture-naming task to elicit single words, and (b) a story-retelling task to elicit connected speech. Four speech measures were compared across sample type (single words vs. connected speech) and across groups (SSD vs. TD): intelligibility, speech accuracy, phonemic inventory, and phonological patterns. Results Interaction effects were found between sample type and group on several speech sound performance measures. Single-word speech samples were found to differentiate the SSD group from the TD group, and were more sensitive than connected speech samples across various measures. The effect size of single-word samples was consistently higher than connected speech samples for three measures: intelligibility, speech accuracy, and phonemic inventory. The gap in sample type informativeness may be attributed to salience and avoidance effects, given that children tend to avoid producing unfamiliar phonemes in connected speech. The number of phonological patterns produced was the only measure that revealed no gap between two sampling types for both groups. Conclusions On measures of intelligibility, speech accuracy, and phonemic inventory, obtaining a single-word sample proved to be a more informative method of differentiating children with SSD from TD children than connected speech samples. This finding may guide SLPs in their choice of sampling type when they are under time pressure. We discuss how children's performance on the connected speech sample may be biased by salience and avoidance effects and/or task design, and may, therefore, not necessarily reveal a poorer performance than single-word samples, particularly in intelligibility, speech accuracy, and the number of phonological patterns, if these task limitations are circumvented. Our findings show that the performance gap, typically observed between the two sampling types, largely depends on which performance measures are evaluated with the speech sample. Our study is the first to address sampling type differences in SSD versus TD children and has significant clinical implications for SLPs looking for sampling types and measures that reliably identify SSD in preschool-aged children.