Brain and Language最新文献

The volume by Harris (1992) was published at a time when research on the cognitive effects of bilingualism was in its infancy. In this article I revisit the chapter I contributed to that volume and evaluate the extent to which the arguments presented there remain valid. Specifically, I review three claims I made, namely, that the effects of bilingual experience extend into nonverbal domains, that these effects were continuous in nature and not categorical, and that selective attention was the key to explaining cognitive change in bilinguals. Thirty years later, these claims remain largely intact. In contrast, the claim that the mechanism for the effects comes from a specific aspect of linguistic processing that transfers to other domains must be rejected.

Past studies showed that metaphoric expressions (e.g., "she was cold to him") require more cognitive-neural effort than literal paraphrases (e.g., "she was indifferent to him"). In event-related potentials (ERP) studies, this was revealed as an N400, a late positivity (LP), and/or a late negativity (LN). We investigated whether stimulus emotionality and task demands influence these ERP correlates and metaphor processing. In Experiment 1, participants read emotional/neutral metaphorical/literal sentences and performed a sensicality judgement task. Emotional metaphors, in comparison to emotional literal sentences, showed a widespread N400 effect (300-450 ms) and a left-anterior LN (450-850 ms). In Experiment 2, participants simply read the sentences and participation was verified by occasional post-trial comprehension questions. Emotional metaphors elicited a more positive LP (450-850 ms) than emotional literal sentences. Findings indicate that stimulus emotionality and task demand co-determine the extent to which emotion- and semantic- related neural resources are recruited during metaphor comprehension.

How our brain integrates single words into larger linguistic units is a central focus in neurolinguistic studies. Previous studies mainly explored this topic at the semantic or syntactic level, with few looking at how cortical activities track word sequences with different levels of semantic correlations. In addition, prior research did not tease apart the semantic factors from the syntactic ones in the word sequences. The current study addressed these issues by conducting a speech perception EEG experiment using the frequency-tagging paradigm. Participants (N = 25, Mean_age = 23;4, 16 girls) were asked to listen to different types of sequences and their neural activity was recorded by EEG. We also constructed a model simulation based on surprisal values of GPT-2. Both the EEG results and the model prediction show that low-frequency neural activity tracks syntactic information through semantic mediation. Implications of the findings were discussed in relation to the language processing mechanism.

Although previous research has shown that speakers adapt on the words they use, it remains unclear whether speakers adapt their phonological representations, leading them to perceive new phonemic contrasts following a social interaction. This event-related potential (ERP) study investigates whether the neuronal responses to the perception of the /e/-/ε/ vowel merger in Northern French speakers show evidence for discriminating /e/ and /ε/ phonemes after interacting with a speaker who produced this contrast. Northern French participants engaged in an interactive map task and we measured their ERP responses elicited after the presentation of a last syllable which was either phonemically identical to or different from preceding syllables. There was no evidence for discrimination between /e/ and /ε/ phonemes before the social interaction, while mismatch negativity (MMN) and late responses revealed /e/-/ε/ discrimination after the social interaction. The findings suggest rapid neuronal adaptations of phonemic representations thanks to the social interaction.

Anxiety experienced when interacting in a foreign language hinders communication through detrimental behavioral, cognitive, and somatic effects. Despite its impact, there is limited research on how neural asymmetry relates to foreign language anxiety (FLA). While researchers have investigated FLA through brain imaging, there remains an absence of studies examining its correlation with frontal alpha asymmetry. Understanding FLA in the context of frontal alpha asymmetry is significant because it can reveal specific neural mechanisms underlying this anxiety. We investigated the associations between listening and speaking FLA - across behavioral, cognitive, and somatic domains - and participants' resting-state electroencephalography (EEG) signals prior to verbal interactions in a foreign language. The results revealed that significantly higher right-left frontal alpha asymmetry was associated with greater reported FLA in most listening and all of the speaking domains. This study offers insight into the neural processes in connection with FLA, highlighting the significance of frontal alpha asymmetry as a potential neural marker for understanding and addressing its unique challenges.

Developmental Language Disorder (DLD) is a common neurodevelopmental condition characterized by significant difficulty with language learning, comprehension, and expression. The neurocognitive bases of DLD are underspecified but are thought to be related, in part, to altered basal ganglia (BG). The BG are known to have a high level of brain iron, which contributes to myelination and dopaminergic pathways among other physiological mechanisms. In this study, we investigated whether a brain iron imbalance might contribute to the altered BG function that characterizes individuals with DLD. Using a T2*-weighted signal, we compared BG brain iron levels in 7-to-13-year olds with DLD and typical language development (TD). We found a significant age-by-group interaction in the caudate with children with DLD showing a positive association between brain iron and age, which was not the case in TD children. A sex-by-age-by-group interaction was also reported in the right putamen and right nucleus accumbens. Higher brain iron in the caudate was associated with poorer story recall; there was no relation between brain iron levels and recall of word lists. This first-ever investigation of brain iron levels in individuals with DLD provides preliminary evidence of an abnormal developmental trajectory of brain iron balance and offers a potential explanation for the altered BG function and verbal impairments that characterize DLD.

Selective speech adaptation refers to the phenomenon where repeated exposure to identical speech sounds temporarily reduces sensitivity to that sound. We used EEG to track the time-course of this effect. Participants were first exposed to the Dutch vowels /e/ or /ø/ and subsequently identified ambiguous sounds halfway between these phonemes. In over 90 % of the trials, the ambiguous speech sounds were perceived as the opposite phoneme to the one they were repeatedly exposed to. This perceptual shift was linked to late EEG deviations, starting around 575 ms after sound onset, which were primarily located in the left superior temporal gyrus. These findings highlight a strong link between the perceptual interpretation of ambiguous phonemes and late brain potentials. As selective speech adaptation can occur at various levels within the auditory processing hierarchy, the observed EEG effects likely reflect activity at a higher-order cortical stage involved in resolving perceptual ambiguity.

An ERP experiment was conducted to investigate the common and distinct neurocognitive mechanisms underlying the on-line processing of two types of politeness maxims (self-depreciation and other-elevation) and the individual differences during sentence reading. Electroencephalograms were recorded while participants read sentences containing pragmatically appropriate or inappropriate honorific or humble terms. When collapsing all participants' data, inappropriate humble and honorific terms elicited N400 and P600 effects, respectively, which could reflect semantic processing costs and rechecking processes, respectively. More importantly, communication abilities modulated N400 and late negativity effects for appropriateness for humble but not honorific terms. In contrast, perspective-taking and emphatic concern modulated N400 and late positivity effects, respectively, for honorific but not humble terms. Moreover, some commonness of the appropriateness effect modulation by individual variables was also observed. These results are discussed in terms of the commonness and individuality of neurocognitive mechanisms underlying the processing of different politeness maxims during sentence comprehension.

Hemispheric specialization of different functions is proposed to confer evolutionary benefits, yet the behavioral impacts of lateralization and its cognitive and neural mechanisms remain unclear. This study investigated the effect of lateralization pattern between language and spatial attention on dual-task performance and its association with callosal connectivity. Functional lateralization was assessed using fMRI verbal fluency and landmark tasks, and interhemispheric connections were evaluated through diffusion-weighted imaging. The typical lateralization pattern enhanced overall performance and reduced interference in dual-task compared to the co-lateralized pattern (both functions lateralized to one hemisphere). However, no differences were observed between the mirrored pattern (right language dominance and left attention dominance) and the co-lateralized pattern. While callosal connectivity did not significantly differ among groups, a negative correlation was observed between the lateralization degree and callosal connectivity. Our findings partially support the functional crowding hypothesis and offer insights into neurocognitive mechanisms underlying functional reorganization after brain lesions.

Introduction: Although many white matter tracts underlying language functions have been identified, even in aggregate they do not provide a sufficiently detailed and expansive picture to enable us to fully understand the computational processes that might underly language production and comprehension. We employed diffusion tensor tractography (DTT) with a tensor distribution model to more extensively explore the white matter tracts supporting core language functions. Our study was guided by hypotheses stemming largely from the aphasia literature.

Methods: We employed high angular resolution diffusion imaging (HARDI) with a dual region of interest tractography approach. Our diffusion tensor distribution model uses a mixture of Wishart distributions to estimate the water molecule displacement probability functions on a voxel-by-voxel basis and to model crossing/branching fibers using a multicompartmental approach.

Results: We replicated the results of previously published studies of tracts underlying language function. Our study also yielded a number of novel findings: 1) extensive connectivity between Broca's region and the entirety of the middle and superior frontal gyri; 2) extensive interconnectivity between the four subcomponents of Broca's region, pars orbitalis, pars triangularis, pars opercularis, and the inferior precentral gyrus; 3) connectivity between the mid-superior temporal gyrus and the transverse gyrus; 4) connectivity between the mid-superior temporal gyrus, the transverse gyrus, and the planum temporale and the inferior and middle temporal gyri; and 5) connectivity between mid- and anterior superior temporal gyrus and all components of Broca's region.

Discussion: These results, which replicate the results of prior DTT studies, also considerably extend them and thereby provide a fuller picture of the structural basis of language function and the basis for a novel model of the neural network architecture of language function. This new model is entirely consistent with discoveries from the aphasia literature and with parallel distributed processing conceptualizations of language function.