Brain and Language

Cross-linguistic activation is unavoidable in bilinguals and they require language control to manage it. In this study, it is posited that Relative Language Distance (RLD; the extent of lexical feature-similarity between bilinguals languages) can affect the extent of cross-linguistic activation and hence influence bilingual language control. This was investigated via an er-fMRI word-translation task on three similar bilingual groups but with varying RLDs: Dutch-English (low-RLD), Hindi-English (intermediate-RLD) and Cantonese-English (high-RLD). Cross-linguistic conflict and the degree of conflict monitoring/control necessary to manage it were expected to increase with decreasing RLD across groups and be appropriately reflected in the activity of conflict monitoring/control neural regions, such as the ACC (anterior cingulate cortex). Analysis revealed a significantly differential ACC response across the groups, reflecting its adaptation to differential conflict monitoring/control demands generated by RLD. The findings provide emerging evidence for RLD as a dimension of bilingualism impacting bilingual language control processes and neurobiology.

The functional organization of first (L1) and second (L2) language processing in bilinguals remains a topic of great interest to the neurolinguistics community. Functional magnetic resonance imaging (fMRI) studies report meaningful differences in the location and extent of hemodynamic changes between tasks performed in the L1 and L2, yet there is no consensus on whether these networks can be considered truly distinct. In part, this may be due to the multiplicity of task designs implemented in such studies, which complicates the interpretation of their findings. This paper compares the results of previous bilingual meta-analyses to a new ALE meta-analysis that categorizes neuroimaging studies by task design. Factors such as the age of L2 acquisition (AoA) and the L2 language proficiency level of participants are also considered. The findings support previous accounts of the effect of participant characteristics on linguistic processing, while at the same time revealing dissociable differences in fMRI activation for L1 and L2 networks within and across tasks that appear independent of these external factors.

At first glance, the brains language network appears to be universal, but languages clearly differ. How does the brain adapt to the specific details of individual grammatical systems? Here, we present an MEG study on case and agreement in Hindi and Nepali. Both languages use split-ergative case systems. However, these systems interact with verb agreement differently - in Hindi, case features conspire to determine which noun phrase (NP) the verb agrees with (subject, object, or neither), but in Nepali the verb always agrees with the subject NP. We found that left inferior frontal and left anterior temporal regions are sensitive to case features in both languages. Across case configurations, these same brain areas in Hindi participants show different patterns of activity for sentences that require masculine vs. feminine marking on the verb, before the comprehenders encounter it. Additionally, the left temporoparietal junction in Hindi shows different activity for subject and object agreement configurations. Both findings are not observed in Nepali participants. We suggest that this brain response demonstrates a unique-to-Hindi selection of an agreement controller and pre-encoding of the verbs morphological features. This shows that brain activity reflects psycholinguistic processes that are intimately tied to grammatical features. HighlightsO_LIThe left inferior frontal lobe and the left anterior temporal lobe distinguish accusative objects versus bare object NPs in Hindi and Nepali, and pre-emptively encode gender agreement features in Hindi. C_LIO_LIThe left inferior parietal lobe shows a differential sensitivity to object-agreement and subject-agreement constructions in Hindi that is absent in Nepali C_LIO_LIMEG can reveal differences in neural activity that reflect specific requirements of different grammatical systems C_LI

The use of multiple languages modulates the neural mechanisms of selective attention, but it is unclear whether these adaptations require continuous engagement and active second language usage. Here we examined whether language usage shapes selective attention in bilingualism, and what neural processes might this engage. 48 highly proficient English-French bilinguals listened to naturalistic speech streams in their first or second language, paired with either linguistic and non-linguistic interference. Participants were matched on their L2 proficiency, but were either Active, Moderate, or Inactive users of their second language. The results revealed usage-related modulation of oscillatory activity in the alpha band, with more efficient inhibitory control in Active and Moderate users leading to behavioural resilience to interference. In contrast, usage did not affect lower-level perceptual tracking of speech, as captured by mTRF decoding of speech envelopes across frequency bands. Taken together, our findings show that resilience to interference during language processing is not dependent on the perceptual speech tracking, but rather on the capacity to recruit higher-level attentional control mechanisms, a process that is dynamically shaped by bilinguals L2 usage.

In principle, functional neuroimaging provides uniquely informative data in addressing linguistic questions, because it can indicate distinct processes that are not apparent from behavioral data alone. This could involve adjudicating the source of unacceptability via the different patterns of elicited brain responses to different ungrammatical sentence types. However, it is difficult to interpret brain activations to syntactic violations. Such responses could reflect processes that have nothing intrinsically related to linguistic representations, such as domain-general executive function abilities. In order to facilitate the potential use of functional neuroimaging methods to identify the source of different syntactic violations, we conducted an fMRI experiment to identify the brain activation maps associated with two distinct syntactic violation types: phrase structure (created by inverting the order of two adjacent words within a sentence) and subject islands (created by extracting a wh-phrase out of an embedded subject). The comparison of these violations to control sentences surprisingly showed no indication of a generalized violation response, with almost completely divergent activation patterns. Phrase structure violations seemingly activated regions previously implicated in verbal working memory and structural complexity in sentence processing, whereas the subject islands appeared to activate regions previously implicated in conceptual-semantic processing, broadly defined. We review our findings in the context of previous research on syntactic and semantic violations using event- related potentials. Although our results suggest potentially distinct underlying mechanisms underlying phrase structure and subject island violations, our results are tentative and suggest important methodological considerations for future research in this area.

Although psycho-/neuro-linguistics has assumed a distinction between morphological and syntactic structure building as in traditional theoretical linguistics, this distinction has been increasingly challenged by theoretical linguists in recent years. Opposing a sharp, lexicalist distinction between morphology and syntax, non-lexicalist theories propose common morpho-syntactic structure building operations that cut across the realms of "morphology" and "syntax", which are considered distinct territories in lexicalist theories. Taking advantage of two pairs of contrasts in Mandarin Chinese with desirable linguistic properties, namely compound vs. simplex nouns (the "morphology" contrast, differing in morphological structure complexity per lexicalist theories) and separable vs. inseparable verbs (the "syntax" contrast, differing in syntactic structure complexity per lexicalist theories), we report one of the first pieces of evidence for shared neural responses for morphological and syntactic structure complexity in language comprehension, supporting a non-lexicalist view where shared neural computations are employed across morpho-syntactic structure building. Specifically, we observed that the two contrasts both modulated neural responses in left anterior and centro-parietal electrodes in an a priori 275:400 ms time window, corroborated by topographical similarity analyses. These results serve as preliminary yet prima facie evidence towards shared neural computations across morphological and syntactic structure building in language comprehension.

A fundamental question in the cognitive neuroscience of language is how grammatical representations are reflected in the organization and activity of the brain. This is challenging in part because superficial differences between languages, e.g., word order, exert different demands on the memory systems that process these structures. Here, we present an electroencephalography (EEG) study to investigate the brains responses to wh-constructions in English, Urdu, and Mandarin Chinese. In addition to the different word orders, writing systems, and morphological typologies of the 3 languages, these languages diverge with regard to how wh-constructions are formed: English requires filler-gap dependencies for wh-objects, whereas Urdu and Mandarin Chinese do not. We use a rapid parallel reading task, in which short sentences are displayed in parallel for 200ms to mitigate the different demands placed on memory systems. We show that neural responses distinguish wh-object constructions from their controls in midline anterior (Urdu, Mandarin Chinese) and right posterior sensors (English, Mandarin Chinese), from 200-400ms (English, Mandarin Chinese) and 500-800ms (English, Urdu). Although there is no detectable uniform, language-invariant response to wh-constructions across languages, there are a number of shared features in the evoked response between any pair of languages, i.e., wh-in-situ constructions generate an evoked response in midline anterior sensors. Moreover, behavioral evidence shows a robust cross-language cost of processing wh-object constructions, regardless of their surface form. This demonstrates that readers of diverse languages can process some grammatical information in a short 200ms fixation, and that the RPVP methodology may enable new ways of linking cognitive neuroscience of language to comparative syntax, i.e., the systematic description of similarities and differences between grammatical structures.

A network of left frontal and temporal brain regions supports high-level language processing-- including the processing of word meanings, as well as word-combinatorial processing--across presentation modalities. This core language network has been argued to store our knowledge of words and constructions as well as constraints on how those combine to form sentences. However, our linguistic knowledge additionally includes information about sounds (phonemes) and how they combine to form clusters, syllables, and words. Is this knowledge of phoneme combinatorics also represented in these language regions? Across five fMRI experiments, we investigated the sensitivity of high-level language processing brain regions to sub-lexical linguistic sound patterns by examining responses to diverse nonwords--sequences of sounds/letters that do not constitute real words (e.g., punes, silory, flope). We establish robust responses in the language network to visually (Experiment 1a, n=605) and auditorily (Experiments 1b, n=12, and 1c, n=13) presented nonwords relative to baseline. In Experiment 2 (n=16), we find stronger responses to nonwords that obey the phoneme-combinatorial constraints of English. Finally, in Experiment 3 (n=14) and a post-hoc analysis of Experiment 2, we provide suggestive evidence that the responses in Experiments 1 and 2 are not due to the activation of real words that share some phonology with the nonwords. The results suggest that knowledge of phoneme combinatorics and representations of sub-lexical linguistic sound patterns are stored within the same fronto-temporal network that stores higher-level linguistic knowledge and supports word and sentence comprehension.

Ergativity marks subject arguments as agents of a transitive event and thereby signals verbal transitivity and influences language comprehension. We report here on an event-related brain potentials (ERP) study in Hindi, in which we investigated this interconnection to ascertain whether the ergative case as a processing cue and its ERP correlates can be generalized across and within ergative languages. The case marking on the subject argument (ergative or nominative case) in our study either matched or mismatched with the transitivity of the light verb (transitive or intransitive) in compound light verb constructions. Ergative case violations due to an intransitive light verb evoked an N400 effect, whereas nominative case violations due to a transitive light verb elicited a P600 effect. The results reveal neurophysiological differences in the processing of ergative and nominative case alignment modulated by the transitivity of the light verbs. The findings highlight the need for cross-linguistic research to aim beyond universality and elucidate the mechanism underlying the processing of language-specific structural variations.

This neuroimaging study investigated the neural infrastructure of sentence-level language production. We compared brain activation patterns, as measured with BOLD-fMRI, during production of sentences which differed in verb argument structures (intransitives, transitives, ditransitives) and the lexical status of the verb (known verbs or pseudo-verbs). An example for the type of sentence to be produced started a mini-block of six sentences with the same structure. For each trial, participants were first given the (pseudo-)verb followed by three geometric shapes to serve as verb arguments in the sentences. Production of sentences with known verbs yielded greater activation compared to those with pseudo-verbs in the core language network of left inferior frontal gyrus, the left posterior middle temporal gyrus, and a more posterior middle temporal region extending into the angular gyrus (LpMTG/AG), analogous to effects observed in language comprehension. Increasing the number of verb arguments led to greater activation in an overlapping left pMTG/AG area, particularly for known verbs, as well as in the bilateral precuneus. Thus, producing sentences with more complex structures using existing verbs lead to increased activation in the language network, suggesting some reliance on memory retrieval of stored lexical-syntactic information during sentence production. This study thus provides evidence from sentence-level language production in line with functional models of the language network that have so far been mainly based on single word production, comprehension and processing in aphasia.

French accentuation is held to belong to the level of the phrase. Consequently French is considered a language without accent with speakers that are deaf to stress. Recent ERP-studies investigating the French initial accent (IA) however demonstrate listeners to not only discriminate between different stress patterns, but also expect words to be marked with IA early in the process of speech comprehension. Still, as words were presented in isolation, it remains unclear whether the preference applied to the lexical or to the phrasal level. In the current ERP-study, we address this ambiguity and manipulate IA on words embedded in a sentence. Furthermore, we orthogonally manipulate semantic congruity to investigate the interplay between accentuation and later speech processing stages. Results reveal an early fronto-centrally located negative deflection when words are presented without IA, indicating a general dispreference for words presented without IA. Additionally, we found an effect of semantic congruity in the centro-parietal region (the traditional region for N400), which was bigger for words without IA than for words with IA. Furthermore, we observed an interaction between metrical structure and semantic congruity such that {+/-}IA continued to modulate N400 amplitude fronto-centrally, but only in the sentences that were semantically incongruent. The results indicate that presenting word without initial accent hinders semantic conflict resolution. This interpretation is supported by the behavioral data which show that participants were slower and made more errors words had been presented without IA. As participants attended to the semantic content of the sentences, the finding underlines the automaticity of stress processing and indicates that IA may be encoded at a lexical level where it facilitates semantic processing.

Language processing is supported by distributed neural systems. Yet most research examines these systems at the population-average level, obscuring how individual cognitive differences shape language-related brain activity. In this study, we combined comprehensive cognitive assessments and task-based fMRI in a large sample of healthy adults (N = 205) to examine how variability in linguistic knowledge, working memory, processing speed, and non-verbal reasoning influenced neural responses in four language tasks: lexical decision, picture naming, sentence comprehension, and sentence production. All tasks engaged canonical left-lateralized language regions. However, individual differences in cognitive skills were not associated with modulations within commonly activated regions, but rather with modulations in domain-general systems outside traditional perisylvian language areas, mainly the default mode and dorsal attention networks. Notably, activations in these domain-general regions were predominantly negatively correlated with cognitive skills, indicating that individuals with lower cognitive skills draw on these broader neural resources more than higher-skilled individuals, possibly as a compensatory mechanism. These results reveal that while canonical language regions are consistently engaged during language tasks, the recruitment of domain-general systems acts as a variable resource modulated by individuals cognitive skills. Overall, our findings demonstrate that individual cognitive profiles determine how distributed brain systems are dynamically engaged to scaffold language processing.

A central question in psycholinguistics in visual word recognition is whether morphologically complex words are obligatorily decomposed into stems and affixes during visual word recognition or whether whole- word access can occur when forms are frequent and familiar. The present study investigated how morphological complexity and lexical frequency jointly shape neural responses by leveraging Korean nominal inflection, whose transparent stem-suffix structure permits a clean dissociation between base (stem) frequency and surface (whole- word) frequency. Twenty-five native Korean speakers completed a rapid event-related fMRI lexical decision task involving simple and inflected nouns that varied parametrically in both frequency measures. Representational similarity analysis (RSA) revealed robust encoding of surface frequency--but not base frequency--in the inferior frontal gyrus (IFG) pars opercularis and supramarginal gyrus (SMG), with significantly stronger correlations for inflected than simple nouns. Univariate analyses converged with this result: surface frequency selectively increased activation for inflected nouns in inferior parietal regions, whereas base frequency showed no reliable effects in any ROI. These findings challenge models positing obligatory pre-lexical decomposition, instead supporting accounts in which morphological processing is shaped by post-lexical, usage-driven lexical statistics. Taken together, our findings shed light on a distributed perspective on morphological processing, suggesting that structural and statistical factors jointly constrain access to morphologically complex forms.

Speech is a complex and ambiguous acoustic signal that varies significantly within and across speakers. A prevalent and ubiquitous example of such variation is accented speech, to which humans adapt extremely rapidly. The goal of this study is to uncover the neurobiological bases of the attunement process that enables such fluent comprehension. Twenty-four native English participants listened to words spoken by an unaccented "canonical" American talker and two "accented" talkers, and performed a word-picture matching task, while magnetoencephalography (MEG) was recorded. Accented speech was created by including systematic phonological substitutions within the word (e.g. [s] [->] [sh]). Activity in the auditory cortex (superior temporal gyrus) was greater for accented speech, but, critically, this was not attenuated by exposure. By contrast, prefrontal regions showed an interaction between the presence of an accent and amount of exposure: while activity decreased for canonical speech over time, responses to accented speech remained consistently elevated. Grainger causality analyses further revealed that prefrontal responses serve to modulate activity in auditory regions, suggesting the recruitment of top-down processing to decode accented signal. In sum, our results show that accented speech does not elicit the same prefrontal reduction in amplitude over time that unaccented speech does, and points to a dynamic exchange of information between the prefrontal and auditory cortices in order to recalculate phonetic classification and subsequent identification of lexical items. Significance statementHuman ability to adapt to different peoples idiosyncratic pronunciations is a hallmark of speech comprehension. This study aims to address whether adaptation to speakers accents manifests itself at the perceptual level (i.e. through adaptation of low-level neural responses in the auditory cortex) or at the post-perceptual level (i.e. higher-order regions correcting the sensory signal received from auditory cortex). Our results support the post-perceptual hypothesis: we found that responses in auditory cortex emitted an error-like signal that was invariant to exposure; whereas responses in the prefrontal cortex were modulated by exposure. These findings provide initial insight into accent adaptation, and illuminate the computational stages supporting speech comprehension more generally.

The extent to which the language production and comprehension systems overlap remains debated. We address this debate using a dataset where participants engaged in unscripted conversations, while scanned with fMRI. Word predictability was hypothesized to rely on different processes, depending on whether the word was uttered or heard. We employed the information-theoretic measure of surprisal (the negative log probability of a word occurring, given the preceding context) as a parametric modulator, controlling for the words overall frequency. The results for production surprisal revealed activation in the left superior and inferior frontal gyri and motor areas. A large bilateral cluster in the posterior part of the medial prefrontal cortex extended from the supplementary motor area to the anterior cingulate cortex. The results for comprehension surprisal replicated findings from non-conversational contexts, showing involvement of the bilateral superior temporal gyrus/sulcus, presumably supporting bottom-up processes for prediction error detection. Importantly, no overlap in the neural infrastructure of production and comprehension was observed, suggesting that word predictability processes in production and comprehension differ. We suggest that while the comprehension system handles prediction errors, the production system minimizes these errors through adaptation, all to achieve successful communication.

It is uncontroversial that the syntax of an expression largely determines its meaning. For example, there is no way to interpret a sentence like "the blue hat has a white bow" as telling you that there is a white hat that has blue bow. But to what extent are the brains combinatory interpretive routines exclusively locked into the structures given by syntax? Consider another example: "The blue color of his hat is pretty." This sentence tells us that a color is pretty, that the color is blue and that the color belongs to a hat. What the syntax of this sentence does not give us is a combination of "blue" and "hat." But clearly, if we were to draw a picture of the meaning of this sentence, it would have a blue hat in it. We asked: upon encountering "hat" in this sentence, do our brains combine the features of "blue" with the features of "hat," despite the long distance between them and no direct syntactic relation? By using a known neural measure of conceptual combination in the left anterior temporal lobe, we obtained evidence using MEG that our brains appear to perform such a long-distance conceptual combination that does not track the syntax. Intriguingly, word (or rather concept) order affected the directionality of the effect. While the effect of concept order remains a topic for future work, our results overall suggest that the meaning composition system of language is likely richer than the combinatory steps predicted from syntactic structures.

A fundamental question in language processing research is the degree to which the acceptability and ease of interpretation of a sentence are affected by the moment-by-moment memory encoding and retrieval processes needed to process it in time, vs. the properties of the linguistic representation itself, such as syntactic complexity. This manuscript investigates relative clauses, a crucial testing ground for theories of language processing, using parallel presentation, a technique in which the key elements of the target syntactic dependency are displayed to the visual system at the same time. Compared to serial presentation, parallel presentation mitigates the extent to which complex memory operations must be deployed to process the structure word-by-word. We report on an electroencephalography (EEG) experiment in Mandarin Chinese. Participants were presented with sentences which contained either a subject- or object-modifying subject- or object-extracted relative clause. Sentence presentation was split across two separate screens, with each screen being displayed only for 166ms on average. We find a behavioral preference for subject-extracted relative clauses and distinct EEG signatures for subject- and object-extracted relative clauses. Together, these results - on account of the parallel presentation scheme applied here - provide support for the independent contribution of linguistic representation in processing difficulty and the perspective that relative clause processing involves more than the factors that word by word accounts of this phenomenon would suggest. Further, the EEG result contributes to a growing body of electrophysiology literature attempting to illuminate the processing mechanisms deployed in the context of parallel presentation.

Cortical tracking of speech is relevant for the development of speech perception skills. However, no study to date has explored whether and how cortical tracking of speech is shaped by accumulated language experience, the central question of this study. In 35 bilingual children (6 y.o.) with considerably bigger experience in one language, we collected electroencephalography data while they listened to continuous speech in their two languages. Cortical tracking of speech was assessed at acoustic-temporal and lexico-semantic levels. Children showed more robust acoustic-temporal tracking in the least experienced language, and more sensitive cortical tracking of semantic information in the most experienced language. Additionally, and only for the most experienced language, acoustic-temporal tracking was specifically linked to phonological abilities, and lexico-semantic tracking to vocabulary knowledge. Our results indicate that accumulated linguistic experience is a relevant maturational factor for the cortical tracking of speech at different levels during early language acquisition.

Experimental psychology has long discussed the modality effect, whereby the stimulus modality significantly affects retention of the information presented. In neurolinguistics, however, the effect of stimulus modality on language processing has gained little attention. We conducted a multi-modal event-related potential (ERP) experiment on both native and non-native Spanish speakers to investigate the possibility of a neurophysiological modality effect in language processing. Using morphosyntactically violated and orthographically/phonologically violated stimuli, we elicited a robust N400 and P600 in native speakers. We showed that the N400 has consistent features across modalities, while the P600 has modality-specific features. Specifically, the auditory evoked P600 was characterized by a more gradual slope and a later peak than the visual evoked P600. We discuss this in detail along with other modality effects observed post sensory perception. Among second language (L2) learner groups, those with higher proficiency exhibited more nativelike neurophysiological responses in both modalities when compared to those with lower proficiency. We additionally observed fewer modality-specific differences in low proficiency learners than in higher proficiency learners suggesting that modality-specific specialization in language processing comes with increased proficiency. We further discuss the question of modality-specific differences in the process of neurophysiological nativization, whereby L2 learners ERPs become increasingly on nativelike.

How do different levels of representation interact in the mind? Key evidence for answering this question comes from experimental work that investigates the influence of knowledge of written language on spoken language processing. Here we tested whether learning orthographic representations (through reading) influences pre-lexical phonological representations in spoken-word recognition using a perceptual learning paradigm. Perceptual learning is well suited to reveal differences in pre-lexical representations that might be caused by learning to read because it requires the functional use of pre-lexical representations in order to generalize a learning experience. In a large-scale behavioural study in Chennai, India, 97 native speakers of Tamil with varying reading experience (from completely illiterate to highly literate) participated. In marked contrast to their performance in other cognitive tasks, even completely illiterate participants showed a perceptual learning effect that was not moderated by reading experience. This finding suggests that pre-lexical phonological representations are not substantially changed by learning to read and thus poses important constraints for the debate about the degree of interactivity between different levels of representations during human information processing.