How right is left? Handedness modulates neural responses during morphosyntactic processing

Unveiling the cognitive network organization through cognitive performance

The evaluation of cognitive functions interactions has become increasingly implemented in the cognition exploration. In the present study, we propose to examine the organization of the cognitive network in healthy participants through the analysis of behavioral performances in several cognitive domains. Specifically, we aim to explore cognitive interactions profiles, in terms of cognitive network, and as a function of participants' handedness. To this end, we proposed several behavioral tasks evaluating language, memory, executive functions, and social cognition performances in 175 young healthy right-handed and left-handed participants and we analyzed cognitive scores, from a network perspective, using graph theory. Our results highlight the existence of intricate interactions between cognitive functions both within and beyond the same cognitive domain. Language functions are interrelated with executive functions and memory in healthy cognitive functioning and assume a central role in the cognitive network. Interestingly, for similar high performance, our findings unveiled differential organizations within the cognitive network between right-handed and left-handed participants, with variations observed both at a global and nodal level. This original integrative network approach to the study of cognition provides new insights into cognitive interactions and modulations. It allows a more global understanding and consideration of cognitive functioning, from which complex behaviors emerge.

Symmetry and Asymmetry of the Antegonial Notch

The symmetry of a human organism’s structure is an expression of the general law of development regarding organic life. Assessing the symmetry of the face and its individual components is one of the most important factors when it comes to the overall assessment of a patient’s stomatognathic system and is essential in the planning of orthodontic and prosthetic treatment. The aim of this study is to assess the symmetry of the occurrence and the measurement parameters of the pre-angular notch of the mandible. The study included computed tomography scans of 187 patients who all exhibited a visible pre-angular notch in the mandible. There was a noticeable and measurable asymmetry in the length of the angle of the notches as well as in the area of the notch angles. The differentiation of the right- and left-side measurements points to the existence of a fluctuating asymmetry. Other measurements which describe the pre-angular notch of the lower jaw do not show asymmetry.

Developmental Language Disorder as Syntactic Prediction Impairment

We provide evidence that children with Developmental Language Disorder (DLD) are impaired in predictive syntactic processing. In the current study, children listened passively to auditorily-presented sentences, where the critical condition included an unexpected "filled gap" in the direct object position of the relative clause verb. A filled gap is illustrated by the underlined phrase in "The zebra that the hippo kissed the camel on the nose…", rather than the expected "the zebra that the hippo kissed [e] on the nose", where [e] denotes the gap. Brain responses to the filled gap were compared to a control condition using adverb-relative clauses with identical substrings: "The weekend that the hippo kissed the camel on the nose [e]…". Here, the same noun phrase is not unexpected because the adverb gap occurs later in the structure. We hypothesized that a filled gap would elicit a prediction error brain signal in the form of an early anterior negativity, as we have previously observed in adults. We found an early (bilateral) anterior negativity to the filled gap in a control group of children with Typical Development (TD), but the children with DLD exhibited no brain response to the filled gap during the same early time window. This suggests that children with DLD fail to predict that a relativized object should correspond to an empty position after the relative clause verb, suggesting an impairment in predictive processing. We discuss how this lack of a prediction error signal can interact with language acquisition and result in DLD.

Salience-weighted agreement feature hierarchy modulates language comprehension

The brain establishes relations between elements of an unfolding sentence in order to incrementally build a representation of who is doing what based on various linguistic cues. Many languages systematically mark the verb and/or its arguments to imply the manner in which they are related. A common mechanism to this end is subject-verb agreement, whereby the marking on the verb covaries with one or more of the features such as person, number and gender of the subject argument in a sentence. The cross-linguistic variability of these features would suggest that they may modulate language comprehension differentially based on their relative weightings in a given language. To test this, we investigated the processing of subject-verb agreement in simple intransitive Arabic sentences in a visual event-related brain potential (ERP) study. Specifically, we examined the differences, if any, that ensue in the processing of person, number and gender features during online comprehension, employing sentences in which the verb either showed full agreement with the subject noun (singular or plural) or did not agree in one of the features. ERP responses were measured at the post-nominal verb. Results showed a biphasic negativity-late-positivity effect when the verb did not agree with its subject noun in either of the features, in line with similar findings from other languages. Crucially however, the biphasic effect for agreement violations was systematically graded based on the feature that was violated, which is a novel finding in view of results from other languages. Furthermore, this graded effect was qualitatively different for singular and plural subjects based on the differing salience of the features for each subject-type. These results suggest that agreement features, varying in their salience due to their language-specific weightings, differentially modulate language comprehension. We postulate a Salience-weighted Feature Hierarchy based on our findings and argue that this parsimoniously accounts for the diversity of existing cross-linguistic neurophysiological results on verb agreement processing.

Grammatical processing in two languages: How individual differences in language experience and cognitive abilities shape comprehension in heritage bilinguals

Recent studies have demonstrated variation in language processing for monolingual and bilingual speakers alike, suggesting that only by considering individual differences will an accurate picture of the consequences of language experience be adequately understood. This approach can be illustrated in ERP research that has shown that sentence contexts that traditionally elicit a P600 component in response to a syntactic violation, elicit an N400 response for a subset of individuals. That result has been reported for monolingual speakers processing sentences in their L1 and also for bilinguals processing sentences in their L2. To date, no studies have compared variation in L1 and L2 ERP effects in the very same bilingual speakers. In the present paper, we do that by examining sentence processing in heritage bilinguals who acquired both languages from early childhood but for whom the L2 typically becomes the dominant language. Variation in ERPs produced by the non-dominant L1 and dominant L2 of heritage bilinguals was compared to variation found in monolingual L1 processing. The group-averaged results showed the smallest N400 and P600 responses in the native, but no longer dominant, L1 of heritage bilinguals, and largest in the monolinguals. Individual difference analyses linking ERP variation to working memory and language proficiency showed that working memory was the primary factor related to monolingual L1 processing, whereas bilinguals did not show this relationship. In contrast, proficiency was the primary factor related to ERP responses for no longer dominant L1 for bilinguals, but unrelated to monolingual L1 processing, whereas bilinguals' dominant L2 processing showed an intermediate relationship. Finally, the N400 was absent for bilinguals performing the task in the same language in which they initially learned to read, but significantly larger when bilinguals performed the task in the other language. The results support the idea that proficient bilinguals utilize the same underlying mechanisms to process both languages, although the factors that affect processing in each language may differ. More broadly, we find that bilingualism is an experience that opens the language system to perform fluidly under changing circumstances, such as increasing proficiency. In contrast, language processing in monolinguals was primarily related to relatively stable factors (working memory).

Effects of Dispositional Affect on the N400: Language Processing and Socially Situated Context

We examined whether the N400 Event-Related Potential (ERP) component would be modulated by dispositional affect during sentence processing. In this study, 33 participants read sentences manipulated by direct object type (congruent vs. incongruent) and object determiner type (definite vs. demonstrative). We were particularly interested in sentences of the form: (i) The connoisseur tasted the wine on the tour vs. (ii) The connoisseur tasted the # roof … We expected that processing incongruent direct objects (#roof) vs. congruent objects (wine) would elicit N400 effects. Previous ERP language experiments have shown that participants in (induced) positive and negative moods were differentially sensitive to semantic anomaly, resulting in different N400 effects. Presently, we ask whether individual dispositional affect scores (as measured by the Positive and Negative Affect Schedule; PANAS) would modulate N400 effects as shown previously. Namely, previous results showed larger N400 effects associated with happy moods and attenuated amplitudes associated with sad moods. Results revealed significant N400 effects, driven by the #roof vs. the wine, where larger amplitude differences were found for individuals showing smaller negative affect (NA) scores, thus partially replicating previous findings. We discuss our results in terms of theories of local (lexical) inhibition, such that low NA promotes stronger lexico-semantic links in sentences. Finally, our results support accounts of language processing that include social and biological characteristics of individuals during real-time sentence comprehension.

Brain potentials reveal differential processing of masculine and feminine grammatical gender in native Spanish speakers

Studies of Spanish grammatical gender have shown that native speakers exploit gender cues in determiners to facilitate speech processing and are sensitive to gender mismatches. However, past research has not considered attested distributional asymmetries between masculine and feminine gender, collapsing performance on trials with one or the other gender into a single analysis. We use event-related potentials to investigate whether masculine and feminine grammatical gender elicit qualitatively different brain responses. Forty monolingual Spanish speakers read sentences that were well-formed or contained determiner-noun gender violations. Half of the nouns were masculine and the other half were feminine. Consistent with previous research, brain responses varied along a continuum between LAN- and P600-dominant effects for both gender categories. However, results showed that individuals' ERP response dominance (LAN/P600) systematically differed across the two genders: participants who showed a LAN-dominant response to masculine-noun violations were more likely to show a P600 effect in response to feminine-noun violations. Correlations with individual difference measures further revealed that responses to masculine-noun violations were modulated by performance on the AX-CPT, a measure of cognitive control, whereas responses to feminine-noun violations were modulated by lexical knowledge, as indexed by verbal fluency. Together, the results demonstrate that even when processing features of language that belong to the same "natural class," native speakers can exhibit patterns of brain activity attuned to distributional patterns of language use. The inherent variability in native speaker processing is, therefore, an important factor when explaining purported deviations from the "native norm" reported in other types of populations.

The functional significance of the P600: Some linguistic P600's do localize to language areas

A recent paper in the journal Neuroreport suggested that, upon source localization, the semantic P600 localizes to executive function areas, that is, outside language. But is this true for all types of linguistic P600? We report a cross-sectional source localization study of a classical (agreement) syntactic paradigm.The results show a clear localization to the temporal lobe, in classical language areas.The P600 is probably not a unitary phenomenon in term of source localization, and the question whether it localizes within or outside the language system depends on the type of P600.

Faces with foreign accents: An event-related potential study of accented sentence comprehension

Mounting Event-Related Potential (ERP) research testing the neurocognitive processes of foreign- and native-accented speech comprehension shows that listeners process foreign-accented speech in qualitatively and quantitatively different ways from native-accented speech. Previous ERP research has presented listeners with foreign- and native-accented sentences only, devoid of any cues to the speaker's identity. Additional cues about the foreign-accented speaker identity, such as faces, may be useful in aiding listeners' processing, potentially reducing differences between neurocognitive processes associated with foreign-accented and native-accented speech comprehension. This study tested whether providing listeners with extra-linguistic face cues to the speakers' identity affects the ERP correlates of grammatical and semantic processing of foreign-accented and native-accented sentences. Specifically, we presented listeners with face cues to speaker identity followed by native- and foreign-accented sentences that were identical to Grey and Van Hell (2017), who did not provide face cues. To elucidate the effects of face cues, we compared the present study's Face Cue data with the Grey and Van Hell (2017) No Face Cue data. For grammar processing, the results showed a biphasic Nref-P600 for native-accented speech and a P600 for foreign-accented speech in the Face Cue group. In the No Face Cue group, results for grammar processing showed an Nref for native-accented speech and no significant ERP effects for foreign-accented speech. This result indicates that face cues were effective in aiding processing of foreign-accented sentences. For semantic processing, there were robust N400 effects for native-accented speech and delayed N400s for foreign-accented speech in the Face Cue and No Face Cue groups. This pattern indicates that the extra-linguistic face cue to foreign-accented speaker identity did not affect semantic processing. Overall, the results provide neurocognitive evidence that the integration of speaker and face information aids listeners during the processing of foreign-accented speech, particularly for grammatical processing.

Reduced right-hemisphere ERP P600 grammaticality effect is associated with greater right-hemisphere inhibition: Evidence from right-handers with familial sinistrality

The present study examined the hypothesis that left hemisphere (LH) equivalent language capabilities in the right hemisphere (RH) are inhibited in neurologically intact individuals by testing healthy young right-handers with a history of familial sinistrality (FS+, i.e. with at least one left handed biological relative), a population documented to show greater variability for RH language processing. Event-Related Potential (ERP) and split visual field presentation techniques were combined to assess LH- and RH- biased responses to syntactic category violations. In addition, a bilateral flanker task was used to measure inter-hemispheric inhibition ability in the same set of participants. Replicating prior findings, in addition to the LH-biased P600 grammaticality effect previously seen for right-handers in general, a fair amount, though not all, of FS + right-handers showed RH-biased P600 responses, leading to a reliable RH P600 grammaticality effect at the group level. Capitalizing on the variability of RH P600 responses, our results further revealed that reduced RH-biased P600 effects were reliably correlated with more effective RH inhibition (indexed by smaller reaction time differences between incongruent and neutral flankers presented to the RH via the left visual field). These results corroborated previous findings that the RH is capable of processing syntactic information in a manner qualitatively similar to that in the LH and further demonstrated that LH-equivalent processing in the RH as indexed by the P600 responses is modulated by RH inhibition, contributing to inter-individual variability in syntactic lateralization.

Bi-Directional Evidence Linking Sentence Production and Comprehension: A Cross-Modality Structural Priming Study

Natural language involves both speaking and listening. Recent models claim that production and comprehension share aspects of processing and are linked within individuals (Pickering and Garrod, 2004, 2013; MacDonald, 2013; Dell and Chang, 2014). Evidence for this claim has come from studies of cross-modality structural priming, mainly examining processing in the direction of comprehension to production. The current study replicated these comprehension to production findings and developed a novel cross-modal structural priming paradigm from production to comprehension using a temporally sensitive online measure of comprehension, Event-Related Potentials. For Comprehension-to-Production priming, participants first listened to active or passive sentences and then described target pictures using either structure. In Production-to-Comprehension priming, participants first described a picture using either structure and then listened to target passive sentences while EEG was recorded. Comprehension-to-Production priming showed the expected passive sentence priming for syntactic choice, but not response time (RT) or average syllable duration. In Production-to-Comprehension priming, primed, versus unprimed, passive sentences elicited a reduced N400. These effects support the notion that production and comprehension share aspects of processing and are linked within the individual. Moreover, this paradigm can be used for the exploration priming at different linguistic levels as well as the influence of extra-linguistic factors on natural language use.