Neurodynamics of executive control processes in bilinguals: evidence from ERP and source reconstruction analyses

International audienceThe present study was designed to examine the impact of bilingualism on the neuronal activity in different executive control processes namely conflict monitoring, control implementation (i.e., interference suppression and conflict resolution) and overcoming of inhibition. Twenty-two highly proficient but non-balanced successive French–German bilingual adults and 22 monolingual adults performed a combined Stroop/Negative priming task while event-related potential (ERP) were recorded online. The data revealed that the ERP effects were reduced in bilinguals in comparison to monolinguals but only in the Stroop task and limited to the N400 and the sustained fronto-central negative-going potential time windows. This result suggests that bilingualism may impact the process of control implementation rather than the process of conflict monitoring (N200). Critically, our study revealed a differential time course of the involvement of the anterior cingulate cortex (ACC) and the prefrontal cortex (PFC) in conflict processing. While the ACC showed major activation in the early time windows (N200 and N400) but not in the latest time window (late sustained negative-going potential), the PFC became unilaterally active in the left hemisphere in the N400 and the late sustained negative-going potential time windows. Taken together, the present electroencephalography data lend support to a cascading neurophysiological model of executive control processes, in which ACC and PFC may play a determining role

Pupil Size in Spider Eyes Is Linked to Post-Ecdysal Lens Growth

In this study we describe a distinctive pigment ring that appears in spider eyes after ecdysis and successively decreases in size in the days thereafter. Although pigment stops in spider eyes are well known, size variability is, to our knowledge, reported here for the first time. Representative species from three families (Ctenidae, Sparassidae and Lycosidae) are investigated and, for one of these species (Cupiennius salei, Ctenidae), the progressive increase in pupil diameter is monitored. In this species the pupil occupies only a fourth of the total projected lens surface after ecdysis and reaches its final size after approximately ten days. MicroCT images suggest that the decrease of the pigment ring is linked to the growth of the corneal lens after ecdysis. The pigment rings might improve vision in the immature eye by shielding light rays that would otherwise enter the eye via peripheral regions of the cornea, beside the growing crystalline lens

Les processus de contrôle cognitif et leurs bases neuronales dans le bilinguisme

The present doctoral thesis aimed to study the relation between bilingualism and domain-general executive control. Psycholinguistic research on bilingualism has shown that the sustained co-activation of languages and the need to adapt to the linguistic environment lead to a reinforcement of control abilities in bilinguals. However, the nature of domain-general executive control involvement in multiple language use is a matter of debate. Three studies were conducted in order to investigate this issue at the neuronal level in French-German late bilinguals. Different experimental tasks involving a cognitive conflict were used, certain of them involving a linguistic component (Stroop and negative priming) and the other one involving a motoric component (antisaccade). The main findings collected in the present doctoral thesis showed (1) the behavioral and neurophysiological evidence of enhanced conflict monitoring and inhibition in bilinguals, (2) the more efficient dynamic interplay between the anterior cingulate cortex and the prefrontal cortex in executive control in bilinguals in comparison with monolinguals, and (3) a modulation of executive control by the individual linguistic factors inherent to bilingualism. Taken together, the present findings support psycholinguistic theories postulating domain-general control involvement in bilingualism and reveal the capacity of neuroplastic adaptation as a function of linguistic constraints.L'objectif de la présente thèse de doctorat était d'étudier la relation entre le bilinguisme et le contrôle exécutif général. Les recherches sur le bilinguisme en psycholinguistique ont montré que la co-activation permanente des langues ainsi que la nécessité de s'adapter à l'environnement linguistique peuvent produire un renforcement des capacités de contrôle chez les bilingues. Toutefois, la nature des processus de contrôle impliqués reste controversée. Trois études ont examiné cette question au niveau neuronal chez des bilingues tardifs français-allemand. Différentes tâches expérimentales mettant en jeu un conflit cognitif ont été utilisées, les unes impliquant une composante linguistique (Stroop et amorçage négatif), et une autre impliquant une composante motrice (antisaccades). Les principaux résultats sont les suivants : (1) Renforcement des processus de gestion de conflits et d'inhibition chez les bilingues, (2) Interaction entre le cortex cingulaire antérieur et le cortex préfrontal dans le contrôle cognitif plus efficace chez les bilingues que chez les monolingues et (3) Modulation du contrôle exécutif par divers facteurs linguistiques individuels inhérents au bilinguisme. Prises dans leur ensemble, ces observations corroborent l'hypothèse d'une implication de processus de contrôle général dans le bilinguisme et révèlent des capacités d'adaptation neuroplastique en fonction des contraintes linguistiques

Effect of inhibition efficiency on language switching and Stroop tasks: Evidence from late bilinguals and simultaneous interpreters

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Perceptual adaptation to non-native sound contrasts: Electrophysiological evidence of neuroplasticity in the phonological system related to second language learning

International audienceSecond language (L2) learners frequently encounter difficulty in perceiving specific non-native sound contrasts (Dupoux et al., 2008), i.e. a phenomenon called phonological deafness (Troubetzkoi, 1939). However, if the neurocognitive network underlying phonological processing is plastic to some extent, extensive L2 experience should lead to adaptive processes and eventually to a certain capacity to discriminate non-native phonemic contrasts even in late L2 learners (Best & Strange, 1992; Flege et al., 1997; Iverson et al., 2012). Here, our goal was to examine the extent to which neuroplastic changes take place in the phonological system as a function of L2 experience. We designed an ERP experiment in which the capacity of listeners to discriminate second language phonemic contrasts mediated lexical access. A semantic violation paradigm was used in which the difference between semantically congruent and incongruent items was implemented by a phonemic contrast that was unique to the L2, English (e.g., /ɪ/ - /i/: ship – sheep). Nineteen young adult native speakers of French with intermediate proficiency in English participated in the ERP experiment. Participants listened to sentences that contained either a semantically congruent item (e.g., The anchor of the ship was let down) or an incongruent one (e.g., *The anchor of the sheep was let down) and were asked to perform an acceptability judgement. The ERP data revealed a fronto-central incongruency effect, i.e. a larger negativity for incongruent than congruent words between 180-220 ms after critical word onset. Importantly, this early effect was larger in more proficient L2 learners. Moreover, a centro-parietal N400 incongruency effect was found, i.e. larger negativity for incongruent than congruent words between 350-650 ms. Within this time window, the effect peaked earlier in more proficient L2 learners. The present findings indicate that L2 learners were sensitive to semantic incongruencies mediated by non-native phonemic contrasts. The proficiency-related variations of ERP effects suggest that perceptual sensitivity to non-native sounds depends on the amount and type of sustained non-native language experience. However, the capacity to acquire non-native phonology has previously been found to show considerable inter-individual variability (Pruitt et al., 2006; Golestani & Zatorre, 2009). Thus, in the future it will be of importance to delimitate facilitating and limiting factors for neuroplastic changes in the phonological system. Amongst others, investigations should identify how targeted training can improve the sensitivity to second language phonemic contrasts

Perceptual sensitivity to non-native sounds: ERP evidence of neuroplasticity in the phonological system related to second language learning

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Neuroplasticity in the phonological system: The PMN and the N400 as markers for the perception of non-native phonemic contrasts by late second language learners

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Perception of non-native sounds in a second language: Electrophysiological evidence of neuroplasticity in the phonological system

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Perception of non-native sounds in a second language: Electrophysiological evidence of neuroplasticity in the phonological system

International audienceSecond language learners frequently encounter difficulty in perceiving specific non-native sound contrasts. This phenomenon called phonological deafness rather occurs if the second language (L2) is learned after early childhood and is quite persistent even when high L2 proficiency is attained (Dupoux et al., 2008). However, if the neuronal underpinnings of phonological processing are plastic to a certain degree, late L2 learners should be able to reach the capacity to distinguish non-native phonemic contrasts (Best & Strange, 1992; Flege et al., 1997; Iverson et al., 2012). In the present study, our goal was to examine the extent to which the phonological system in late L2 learners is adaptable. We designed an ERP experiment in which the capacity to discriminate second language phonemic contrasts mediated lexical access. We used a semantic violation paradigm in which the difference between semantically congruent and incongruent items was implemented by a phonemic contrast that was unique to the second language, English, but absent in the first language, French (e.g., /ɪ/ - /i/: ship – sheep). Twelve young adult native speakers of French with intermediate proficiency in English participated in the ERP experiment. Participants heard sentences that contained either a semantically congruent item (e.g., The anchor of the ship was let down) or an incongruent one (e.g., *The anchor of the sheep was let down) and were asked to perform a grammaticality judgement. Preliminary results reveal that second language learners of English showed a larger centro-parietal negativity between 300-500 ms after the onset of semantically incongruent words as compared to congruent target words, i.e. an N400 effect. This finding indicates that L2 learners were sensitive to the semantic incongruency mediated by a phonemic contrast. Critically, the N400 effect size varied as a function of L2 proficiency, i.e. the more proficient the participants, the larger the N400 effect size. Thus, the sensitivity to phonemic contrasts of a second language seems to play a significant role in lexical access. With an increasing capacity to discriminate second language phonemic contrasts, the access to lexical information is facilitated. These findings show that even late learners of a second language can develop a perceptual sensitivity to discriminate non-native sound contrasts, at least at the segmental phonological level, which also indicates that neuroplasticity in the phonological system allows for a certain adaptation to linguistic environmental constraints. Further investigations should explore how targeted training can improve the sensitivity to second language phonemic contrasts