Bilingual lexical selection as a dynamic process:evidence from Arabic-French bilinguals

The nature of the lexical selection process in bilingual spoken word production is one of the pending questions of research on bilingualism. According to one view this competitive process is language-specific, while another holds that it is language-nonspecific (i.e., lexical competition is cross-linguistic). In recent years, research on bilingual language production has seen the rise of a third view that postulates that lexical selection is in fact dynamic and may function as language-specific or nonspecific depending on a number of factors. The aim of the present study was to investigate the lexical selection process among moderately proficient bilinguals whose two languages are typologically distant: Tunisian Arabic and French. The picture-word interference task was used in two experiments where moderately proficient Tunisian Arabic (L1)-French (L2) bilinguals were asked to name pictures in their L2 while ignoring auditory distractors (semantic, phono-translation, phonological, or unrelated) in their L2 (Experiment 1) or their L1 (Experiment 2). Thus, the language context was entirely monolingual in Experiment 1 and bilingual in Experiment 2. In Experiment 1, only a phonological facilitation effect was observed. In Experiment 2, interference was found in the phono-translation, semantic, and phonological conditions. Taken together, these results indicate that cross-language competition occurs among moderately proficient Tunisian Arabic-French bilinguals only in a bilingual context (Experiment 2) as indexed by the phono-translation interference effect observed. Our findings are in line with the recent hypothesis that lexical selection is a dynamic process modulated by factors like language similarity, language proficiency, and the experimental language context

Age-of-acquisition affects word naming in Italian only when stress is irregular.

In Italian, effects of age of acquisition (AoA) have been found in object naming, semantic categorization of words and lexical decision, but not in word naming (reading aloud). The lack of an AoA effect in Italian word naming is replicated in Experiment 1 which involved reading aloud two-syllable words which all have regular spelling-sound correspondences and regular stress patterns. Studies of English word naming have reported stronger effects of AoA for irregular or exception words than for words with regular, consistent spelling-sound correspondences. There are no grapheme-phoneme irregularities in Italian, but words containing three or more syllables can carry either regular stress on the penultimate syllable or irregular stress on the antepenultimate syllable. Experiment 2 found effects of AoA on reading three-syllable words for words with irregular stress. The results are interpreted in terms of the \u27mapping hypothesis\u27 of AoA, with effects arising as a result of a difficulty to generalize earlier-acquired patterns to irregular late-acquired words

Visual and auditory perceptual strength norms for 3,596 French nouns and their relationship with other psycholinguistic variables

Perceptual experience plays a critical role in the conceptual representation of words. Higher levels of semantic variables such as imageability, concreteness, and sensory experience are generally associated with faster and more accurate word processing. Nevertheless, these variables tend to be assessed mostly on the basis of visual experience. This underestimates the potential contributions of other perceptual modalities. Accordingly, recent evidence has stressed the importance of providing modality-specific perceptual strength norms. In the present study, we developed French Canadian norms of visual and auditory perceptual strength (i.e., the modalities that have major impact on word processing) for 3,596 nouns. We then explored the relationship between these newly developed variables and other lexical, orthographic, and semantic variables. Finally, we demonstrated the contributions of visual and auditory perceptual strength ratings to visual word processing beyond those of other semantic variables related to perceptual experience (e.g., concreteness, imageability, and sensory experience ratings). The ratings developed in this study are a meaningful contribution toward the implementation of new studies that will shed further light on the interaction between linguistic, semantic, and perceptual systems

Differential involvement of the anterior temporal lobes in famous people semantics

The ability to recognize a famous person occurs through semantic memory. Previous neuroimaging studies have shown that the anterior temporal lobes (ATLs) are involved in the recognition of famous people. However, it is still a matter of debate whether the semantic processing of names or pictures of famous people has an impact on the activation of ATLs. The aim of this study was to explore the pattern of activation associated with a semantic processing of famous people based on face and written name stimuli. Fifteen healthy young individuals participated in our fMRI study, in which they were asked to perform a semantic categorization judgment task, based on profession, of visually presented pictures, and names of famous people. Neuroimaging findings showed a common pattern of activation for faces and names mainly involving the inferior frontal regions, the posterior temporal lobe, the visual cortex, and the ATLs. We found that the comparison names vs. pictures lead to significant activation in the anterior superior temporal gyrus. On the other hand, faces vs. names seemed associated with increased activation in the medial ATL. Moreover, our results demonstrated that the functional connectivity network anchored to the medial ATL, compared to the anterior STG, is more connected to the bilateral occipital lobe and fusiform gyrus that are regions implicated in the visual system and visual processing of faces. This study provides critical evidence of the differential involvement of ATL regions in semantics of famous people

Comprehension of concrete and abstract words in semantic variant primary progressive aphasia and Alzheimer’s disease: a behavioral and neuroimaging study

The aim of this study was to investigate the comprehension of concrete, abstract and abstract emotional words in semantic variant primary progressive aphasia (svPPA), Alzheimer’s disease (AD), and healthy elderly adults (HE) Three groups of participants (9 svPPA, 12 AD, 11 HE) underwent a general neuropsychological assessment, a similarity judgment task, and structural brain MRI. The three types of words were processed similarly in the group of AD participants. In contrast, patients in the svPPA group were significantly more impaired at processing concrete words than abstract words, while comprehension of abstract emotional words was in between. VBM analyses showed that comprehension of concrete words relative to abstract words was significantly correlated with atrophy in the left anterior temporal lobe. These results support the view that concrete words are disproportionately impaired in svPPA, and that concrete and abstract words may rely upon partly dissociable brain regions

The role of the left anterior temporal lobe for unpredictable and complex mappings in word reading

The anterior temporal lobes (ATLs) have been consistently associated with semantic processing which, in turn, has a key role in reading aloud single words. This study aimed to investigate (1) the reading abilities in patients with the semantic variant of primary progressive aphasia (svPPA), and (2) the relationship between gray matter (GM) volume of the left ATL and word reading performance using voxel-based morphometry (VBM). Three groups of participants (svPPA, Alzheimer’s Disease, AD and healthy elderly adults) performed a reading task with exception words, regular words and pseudowords, along with a structural magnetic resonance imaging scan. For exception words, the svPPA group had a lower accuracy and a greater number of regularization errors as compared to the control groups of healthy participants and AD patients. Similarly, for regular words, svPPA patients had a lower accuracy in comparison with AD patients, and a greater number of errors related to complex orthography-to-phonology mappings (OPM) in comparison to both control groups. VBM analyses revealed that GM volume of the left ATL was associated with the number of regularization errors. Also, GM volume of the left lateral ATL was associated with the number of errors with complex OPM during regular word reading. Our results suggest that the left ATL might play a role in the reading of exception words, in accordance with its role in semantic processing. Results further support the involvement of the left lateral ATL in combinatorial processes, including the integration of semantic and phonological information, for both exception and regular words

La sémantique, la lecture de mots irréguliers et les lobes temporaux antérieurs

Dans cette recension des écrits nous présentons les résultats d’études comportementales et de neuroimagerie mettant en rapport la sémantique et la lecture de mots irréguliers, ainsi que la sémantique et les lobes temporaux antérieurs (LTA). Plus particulièrement, nous nous concentrons sur l’atteinte de la lecture à voix haute de mots irréguliers, soit la dyslexie de surface, chez la variante sémantique de l’Aphasie Primaire Progressive (vsAPP). Cette maladie neurodégénérative débute par l’atrophie des lobes temporaux antérieurs et touche d’abord la mémoire sémantique. À partir des études comportementales, il est possible de conclure que la dyslexie de surface est très souvent observée chez des patients atteints de vsAPP. Ceci semble mettre en avant le rapport entre la dyslexie de surface et la dégradation de la mémoire sémantique chez ce type de patients. De plus, la nature neurodégénérative de la vsAPP a permis d’établir le rapport entre l’atteinte sémantique et les LTA. Les études de neuroimagerie menées auprès des participants sains ont aussi mis en évidence le rôle des LTA lors du traitement sémantique et lors de la lecture de mots irréguliers. Le rôle des LTA en lecture de mots irréguliers semblerait être celui de la sémantique, plutôt que celui de la lecture ellemême. En somme, les modèles théoriques et computationnels qui postulent l’activation sémantique pour la lecture de mots irréguliers permettraient d’expliquer le profil de lecture et l’atteinte sémantique trouvés en vsAPP, ainsi que le réseau de lecture de mots irréguliers qui inclut le LTA gauche.This review presents the results of behavioural and neuroimaging studies that address the relationship between semantics, irregular word reading and the anterior temporal lobes (ATLs). In particular we focused on acquired surface dyslexia, i.e., irregular word reading impairment , in patients suffering from the semantic variant of primary progressive aphasia (svPPA). svPPA is a neurodegenerative disease that occurs following the atrophy of the ATLs. This disease is early characterized by semantic memory impairments. Taken together, behavioural studies show that svPPA patients often suffer from acquired surface dyslexia. This pattern highlights the relationship between acquired surface dyslexia and semantic knowledge degradation in svPPA. Moreover, the neurodegenerative nature of svPPA has pointed out to the relationship between semantic impairment and the ATLs. Neuroimaging studies in healthy participants have also provided evidence of the role of the ATLs in semantic processing and irregular word reading. The ATLs seem to be related to semantic processing in irregular word reading, more than to irregular word reading itself. In sum, the results of the studies reviewed here provide evidence for theoretical and computational models that predict semantic activation during irregular word reading. This semantic contribution can explain the profile of surface dyslexia in svPPA, as well as the brain network that sustains the processing of this type of words and that includes the left ATL

Effect of temperature and nucleotide on the binding of BiP chaperone to a protein substrate

BiP (immunoglobulin heavy-chain Binding Protein) is a Hsp70 monomeric ATPase motor that plays broad and crucial roles maintaining proteostasis inside the cell. Structurally, BiP is formed by two domains, a nucleotide-binding domain (NBD) with ATPase activity connected by a flexible hydrophobic linker to the substrate-binding domain (SBD). While the ATPase and substrate binding activities of BiP are allosterically coupled, the latter is also dependent on nucleotide binding. Recent structural studies have provided new insights into BiP's allostery; however, the influence of temperature on the coupling between substrate and nucleotide binding to BiP remains unexplored. Here we study BiP's binding to its substrate at the single molecule level using thermo-regulated optical tweezers which allows us to mechanically unfold the client protein and explore the effect of temperature and different nucleotides on BiP binding. Our results confirm that the affinity of BiP for its protein substrate relies on nucleotide binding, by mainly regulating the binding kinetics between BiP and its substrate. Interestingly, our findings also showed that the apparent affinity of BiP for its protein substrate in the presence of nucleotides remains invariable over a wide range of temperatures, suggesting that BiP may interact with its client proteins with similar affinities even when the temperature is not optimal. Thus, BiP could play a role as a "thermal buffer" in proteostasis. This article is protected by copyright. All rights reserved

Liquid methanol Monte Carlo simulations with a refined potential which includes polarizability, nonadditivity, and intramolecular relaxation

Monte Carlo simulations of liquid methanol were performed using a refined ab initio derived potential which includes polarizability, nonadditivity, and intramolecular relaxation. The results present good agreement between the energetic and structural properties predicted by the model and those predicted by ab initio calculations of methanol clusters and experimental values of gas and condensed phases. The molecular level picture of methanol shows the existence of both rings and linear polymers in the methanol liquid phase