On the brain struggles to recognize basic facial emotions with face masks: an fMRI study.

Introduction: The COVID-19 pandemic impacted public health and our lifestyles, leading to new social adaptations such as quarantine, social distancing, and facial masks. Face masks, covering extended facial zones, hamper our ability to extract relevant socio-emotional information from others' faces. In this fMRI study, we investigated how face masks interfere with facial emotion recognition, focusing on brain responses and connectivity patterns as a function of the presence of a face mask. Methods: A total of 25 healthy participants (13F; mean age: 32.64 ± 7.24y; mean education: 18.28 ± 1.31y) were included. Participants underwent task-related fMRI during the presentation of images of faces expressing basic emotions (joy or fear versus neutral expression). Half of the faces were covered by a face mask. Subjects had to recognize the facial emotion (masked or unmasked). FMRI whole-brain and regions-of-interest analyses were performed, as well as psychophysiological interaction analysis (PPI). Results: Subjects recognized better and faster emotions on unmasked faces. FMRI analyses showed that masked faces induced a stronger activation of a right occipito-temporal cluster, including the fusiform gyrus and the occipital face area bilaterally. The same activation pattern was found for the neutral masked > neutral unmasked contrast. PPI analyses of the masked > unmasked contrast showed, in the right occipital face area, a stronger correlation with the left superior frontal gyrus, left precentral gyrus, left superior parietal lobe, and the right supramarginal gyrus. Discussion: Our study showed how our brain differentially struggles to recognize face-masked basic emotions, implementing more neural resources to correctly categorize those incomplete facial expressions.

The relationship between reading abilities and the left occipitotemporal sulcus: A dual perspective study.

Reading activates a region within the left lateral occipitotemporal sulcus (OTS) known as the 'visual word form area' (VWFA). While several studies have investigated the impact of reading on brain structure through neuroplastic mechanisms, it has been recently suggested that individual differences in the pattern of the posterior OTS may predict reading skills in adults. In the present study, we first examined whether the structure and morphology and the anatomical connectivity of the left OTS are associated to reading ability. Second, we explored whether reading skills are predicted by the pattern of the left OTS. We found that reading skills were positively associated with increased connectivity between the left OTS and a network of reading-related regions in the left hemisphere. On the other hand, we did not observe an association between the pattern of the left OTS and reading skills. Finally, we found evidence that the morphology and the connectivity of the left OTS are correlated to its sulcal pattern.

Cingulate cortex morphology impacts on neurofunctional activity and behavioral performance in interference tasks.

Inhibitory control is the capacity to withhold or suppress a thought or action intentionally. The anterior Midcingulate Cortex (aMCC) participates in response inhibition, a proxy measure of inhibitory control. Recent research suggests that response inhibition is modulated by individual variability in the aMCC sulcal morphology. However, no study has investigated if this phenomenon is associated with neurofunctional differences during a task. In this study, 42 participants performed an Attention Network Task and a Numerical Stroop task in an MRI scanner. We investigated differences in brain activity and response inhibition efficiency between individuals with symmetric and asymmetric aMCC sulcal patterns. The results showed that aMCC morphological variability is partly associated with inhibitory control, and revealed greater activation in individuals with symmetric patterns during the Stroop task. Our findings provide novel insights into the functional correlates of the relationship between aMCC morphology and executive abilities.

Investigating sexual dimorphism in human brain structure by combining multiple indexes of brain morphology and source-based morphometry.

Computational morphometry of magnetic resonance images represents a powerful tool for studying macroscopic differences in human brains. In the present study (N participants = 829), we combined different techniques and measures of brain morphology to investigate one of the most compelling topics in neuroscience: sexual dimorphism in human brain structure. When accounting for overall larger male brains, results showed limited sex differences in gray matter volume (GMV) and surface area. On the other hand, we found larger differences in cortical thickness, favoring both males and females, arguably as a result of region-specific differences. We also observed higher values of fractal dimension, a measure of cortical complexity, for males versus females across the four lobes. In addition, we applied source-based morphometry, an alternative method for measuring GMV based on the independent component analysis. Analyses on independent components revealed higher GMV in fronto-parietal regions, thalamus and caudate nucleus for females, and in cerebellar- temporal cortices and putamen for males, a pattern that is largely consistent with previous findings.

The bilingual structural connectome: Dual-language experiential factors modulate distinct cerebral networks.

Bilingualism is a natural laboratory for studying whether the brain's structural connectome is influenced by different aspects of language experience. However, evidence on how distinct components of bilingual experience may contribute to structural brain adaptations is mixed. The lack of consistency, however, may depend, at least in part, on methodological choices in data acquisition and processing. Herein, we adopted the Network Neuroscience framework to investigate how individual differences in second language (L2) exposure, proficiency, and age of acquisition (AoA) - measured as continuous between-subject variables - relate to whole-brain structural organization. We observed that L2 exposure modulated the connectivity of two networks of regions subserving language comprehension and production. L2 proficiency was associated with enhanced connectivity within a rostro-caudal network, which supports language selection and word learning. Moreover, L2 AoA and exposure affected inter-hemispheric communication between control-related regions. These findings expand mechanistic knowledge about particular environmental factors associated with specific variation in brain structure.

Evidence for the Concreteness of Abstract Language: A Meta-Analysis of Neuroimaging Studies.

The neural mechanisms subserving the processing of abstract concepts remain largely debated. Even within the embodiment theoretical framework, most authors suggest that abstract concepts are coded in a linguistic propositional format, although they do not completely deny the role of sensorimotor and emotional experiences in coding it. To our knowledge, only one recent proposal puts forward that the processing of concrete and abstract concepts relies on the same mechanisms, with the only difference being in the complexity of the underlying experiences. In this paper, we performed a meta-analysis using the Activation Likelihood Estimates (ALE) method on 33 functional neuroimaging studies that considered activations related to abstract and concrete concepts. The results suggest that (1) concrete and abstract concepts share the recruitment of the temporo-fronto-parietal circuits normally involved in the interactions with the physical world, (2) processing concrete concepts recruits fronto-parietal areas better than abstract concepts, and (3) abstract concepts recruit Broca's region more strongly than concrete ones. Based on anatomical and physiological evidence, Broca's region is not only a linguistic region mainly devoted to speech production, but it is endowed with complex motor representations of different biological effectors. Hence, we propose that the stronger recruitment of this region for abstract concepts is expression of the complex sensorimotor experiences underlying it, rather than evidence of a purely linguistic format of its processing.

Thinking outside the box: The brain-bilingualism relationship in the light of early neurobiological variability.

Bilingualism represents a distinctive way to investigate the interplay between brain and behaviour, and an elegant model to study the role of environmental factors in shaping this relationship. Past neuroimaging research has mainly focused on how bilingualism influences brain structure, and how eventually the brain accommodates a second language. In this paper, we discuss a more recent contribution to the field which views bilingualism as lens to understand brain-behaviour mappings from a different perspective. It has been shown, in contexts not related to bilingualism, that cognitive performance across several domains can be predicted by neuroanatomical variants determined prenatally and largely impervious to postnatal changes. Here, we discuss novel findings indicating that bilingualism modulates the predictive role of these variants on domain-specific cognition. The repercussions of these findings are potentially far-reaching on multiple levels, and highlight the need to shape more complex questions for progress in cognitive neuroscience approaches to bilingualism.

Sulcal Pattern Variability and Dorsal Anterior Cingulate Cortex Functional Connectivity Across Adult Age.

Background: The dorsal anterior cingulate cortex (dACC) is a key network hub for cognitive control and environmental adaptation. Previous studies have shown that task-based functional activity in this area is constrained by individual differences in sulcal pattern, a morphologic feature of cortex anatomy determined during fetal life and stable throughout development. Methods: By using anatomical magnetic resonance imaging and seed-based resting-state functional connectivity (rsFC), we explored the influence of sulcal pattern variability on the functional architecture of the dACC in a sample of healthy adults aged 20-80 years (n = 173). Results: Overall, rsFC was associated with individual differences in sulcal pattern. Furthermore, rsFC was modulated by the age-sulcal pattern interaction. Conclusion: Our results suggest a relationship between brain structure and function that partly traces back to early stages of brain development. The modulation of rsFC by the age-sulcal pattern interaction indicates that the effects of sulcal pattern variability on the functional architecture of the dACC may change over adulthood, with potential repercussions for brain network efficiency and cognitive function in aging.

Bilingualism as a gradient measure modulates functional connectivity of language and control networks.

There is currently no agreement on which factor modulates most effectively and enduringly brain plasticity in bilingual individuals. Grouping heterogeneous linguistic profiles under a dichotomous condition (bilingualism versus monolingualism) may obscure critical aspects of language experience underlying neural changes, thus leading to variable and often conflicting findings. In the present study, we overcome these limitations by analyzing the individual and joint contribution of L2 AoA, proficiency and usage - all measured as continuous variables - on the resting-state functional connectivity of the brain networks mediating the specific demands of bilingual language processing: the language network and the executive control network. Our results indicate that bilingual experience - defined as a continuous and multifaceted phenomenon - impacts brain plasticity by modulating the functional connectivity both within and between language and control networks. Each experience-related factor considered played a role in changing the connectivity of these regions. Moreover, the effect of AoA was modulated by proficiency and usage. These findings shed new light on the importance of modeling bilingualism as a gradient measure rather than an all-or-none phenomenon.

Bilingual language processing: A meta-analysis of functional neuroimaging studies.

Notwithstanding rising interest, a coherent picture of the brain's representation of two languages has not yet been achieved. In the present meta-analysis we analysed a large number of functional neuroimaging studies focusing on language processing in bilinguals. We used activation likelihood estimation (ALE) to enucleate activation areas involved in bilingual processing and control of different types of linguistic knowledge - lexico-semantics, grammar, phonology - in L1 and L2. Results show that surprisingly, compared to L2, lexico-semantic processing in L1 involves a widespread system of cortico-subcortical regions, especially when L2 is acquired later in life. By contrast, L2 processing recruits regions exceeding the L1 semantic network and relating to executive control processes. Only few regions displayed selective activation for grammar and phonology. Analyses of language switching highlight a functional overlap between domain-general and bilingual language control networks. Collectively, our findings point to a shared neural network for L1 and L2 with few differences depending on the linguistic level. The emerging picture identifies under-investigated issues, offering clear directions for future research.

The relationship between bilingual experience and gyrification in adulthood: A cross-sectional surface-based morphometry study.

Neuroimaging evidence suggests that bilingualism may act as a source of neural plasticity. However, prior work has mostly focused on bilingualism-induced alterations in gray matter volume and white matter tract microstructure, with additional effects related to other neurostructural indices that might have remained undetected. The degree of cortical folding or gyrification is a morphometric parameter which provides information about changes on the brain's surface during development, aging and disease. We used Surface-based Morphometry (SBM) to investigate the contribution of bilingual experience to gyrification from early adulthood to old age in a sample of bilinguals and monolingual controls. Despite widespread cortical folding reductions for all participants with increasing age, preserved gyrification exclusive to bilinguals was detected in the right cingulate and entorhinal cortices, regions vulnerable with normal and pathological brain aging. Our results provide novel insights on experience-related cortical reshaping and bilingualism-induced cortical plasticity in adulthood.

Are you really cursing? Neural processing of taboo words in native and foreign language.

The use of socially opprobrious words (taboo words) is a cross-cultural phenomenon occurring between individuals from almost all social extractions. The neurocognitive correlates of using taboo words in the native language (L1) as compared to their use in a second (L2) language are largely unknown. We used fMRI to investigate the processing of taboo and non-taboo stimuli in monolinguals (Experiment 1) and highly proficient bilinguals (Experiment 2) engaged in lexical decision tasks. We report that for L1 socio-pragmatic knowledge is automatically conveyed and taboo words are processed with less effort than non-taboo words. For L2 the processing of taboo words is more effortful and engages additional structures (anterior cingulate cortex, insula) involved in social-norm representation and evaluation. Our results contribute to understand the interface between language and social-norm processing indicating that lexical processing is affected by socio-pragmatic knowledge, but only when the speaker has a contextual use of the language.

ACC Sulcal Patterns and Their Modulation on Cognitive Control Efficiency Across Lifespan: A Neuroanatomical Study on Bilinguals and Monolinguals.

The anterior cingulate cortex (ACC) is a key structure implicated in the regulation of cognitive control (CC). Previous studies suggest that variability in the ACC sulcal pattern-a neurodevelopmental marker unaffected by maturation or plasticity after birth-is associated with intersubject differences in CC performance. Here, we investigated whether bilingual experience modulates the effects of ACC sulcal variability on CC performance across the lifespan. Using structural MRI, we first established the distribution of the ACC sulcal patterns in a large sample of healthy individuals (N = 270) differing on gender and ethnicity. Second, a participants' subsample (N = 157) was selected to test whether CC performance was differentially affected by ACC sulcation in bilinguals and monolinguals across age. A prevalent leftward asymmetry unaffected by gender or ethnicity was reported. Sulcal variability in the ACC predicted CC performance differently in bilinguals and monolinguals, with a reversed pattern of structure-function relationship: asymmetrical versus symmetrical ACC sulcal patterns were associated with a performance advantage in monolinguals and a performance detriment to bilinguals and vice versa. Altogether, these findings provide novel insights on the dynamic interplay between early neurodevelopment, environmental background and cognitive efficiency across age.

Neuroplasticity across the lifespan and aging effects in bilinguals and monolinguals.

Evidence that bilingualism protects against age-related neurocognitive decline is mixed. One relatively consistent finding is that bilingual seniors have greater grey matter volume (GMV) in regions implicated in executive control (EC) and language processing. Here, we compare the neuroplastic effects of bilingual experience on the EC network of young and aging populations directly, and for the first time we evaluate the extent to which such effects may predict executive control performance across age. We used GMV as an index of neural reserve and response time (RT) performance on the Flanker task for measuring EC efficiency. In the presence of age-related widespread GM deterioration, bilinguals had greater GMV than monolinguals in key regions of interest across age. Moreover, whereas EC performance in monolingual seniors was strictly related to GMV, this was not observed for bilingual seniors or younger participants in either group. Interactions between expected effects-of-age and language group on the relationships between GMV and RT suggested that bilingualism affords differential benefits across the lifespan. In younger participants, greater GMV offered no behavioral benefit on EC performance, whilst it did for seniors. It thus appears that age-related cognitive decline following GMV loss in the EC network is delayed in bilinguals.

Anterior cingulate cortex sulcation and its differential effects on conflict monitoring in bilinguals and monolinguals.

The role of the anterior cingulate cortex (ACC) in modulating the effect of bilingual experience on cognitive control has been reported at both functional and structural neural levels. Individual differences in the ACC sulcal patterns have been recently correlated with cognitive control efficiency in monolinguals. We aimed to investigate whether differences of ACC sulcation mediate the effect of bilingualism on cognitive control efficiency. We contrasted the performance of bilinguals and monolinguals during a cognitive control task (i.e., the Flanker Task) using a stratification based on the participants' ACC sulcal features. We found that performance of the two groups was differentially affected by ACC sulcation. Our findings provide the first evidence that early neurodevelopmental mechanisms may modulate the effect of different environmental backgrounds - here, bilingual vs monolingual experience - on cognitive efficiency.