Dr Alejandro Perez

Hyperscanning is an emerging technique that allows for the study of brain similarities between interacting individuals. This methodology has powerful implications for understanding the neural basis of joint actions, such as conversation; however, it also demands precise time-locking between the different brain recordings and sensory stimulation. Such precise timing, nevertheless, is often difficult to achieve. Recording auditory stimuli jointly with the ongoing high temporal resolution neurophysiological signal presents an effective way to control timing asynchronies offline between the digital trigger sent by the stimulation program and the actual onset of the auditory stimulus delivered to participants via speakers/headphones. This configuration is particularly challenging in hyperscanning setups due to the general increased complexity of the methodology. In other designs using the related technique of pseudo-hyperscanning, combined brain-auditory recordings are also a highly desirable feature, since reliable offline synchronization can be performed by using the shared audio signal. Here, we describe two hardware configurations wherein the real-time delivered auditory stimulus is recorded jointly with ongoing electroencephalographic (EEG) recordings. Specifically, we describe and provide customized implementations for joint EEG-audio recording in hyperscanning and pseudo-hyperscanning paradigms using hardware and software from Brain Products GmbH.•Joint EEG-audio recording configuration for hyperscanning and pseudo-hyperscanning paradigms.•Near zero-latency playback of auditory signal captured by a microphone.•Precise alignment between EEG and auditory stimulation. [Display omitted]

BACKGROUND: The interpretation of non-verbal social signals relies heavily on the ability to perceive biological motion. The posterior superior temporal sulcus is an important part of a network involved in biological motion processing. However, the underlying functional organization remains poorly understood. Several studies have suggested topographical representation of motion from different body parts within this region. However, other studies have shown that the posterior superior temporal sulcus responds equally to any body part. OBJECTIVE: Through the use of functional magnetic resonance imaging, the effects of socially relevant biological motion stimuli to activate a specific cortical area within posterior superior temporal sulcus, even if different body parts are involved in motion, will be analyzed. DESIGN, TIME AND SETTING: A functional magnetic resonance imaging, block-design was performed at the Magnetic Resonance Imaging, Surgical Medical Investigation Center, Havana, Cuba between 2004 and 2005. PARTICIPANTS: Thirteen healthy volunteers, from 19 to 55 years of age and comprising eight males and five females, were included in the study. METHODS: A conjunction analysis of responses to natural, dynamic, fearful, facial expressions and point-light, body-motion animations. MAIN OUTCOME MEASURES: The corresponding functionally specialized areas, as well as neural areas significant for both types of stimuli, were identified. RESULTS: One region within the posterior superior temporal sulcus of the right hemisphere was equally activated by facial and body complex motion. CONCLUSION: A site of common neural activity existed within the posterior superior temporal sulcus, which was not specific to a biological motion type. In addition, the activity was not related to a topographically organized body-part map, which suggested high-level visual representation of biological motion in this region.

Numerous studies have shown that the native language influences foreign word recognition and that this influence is modulated by the proficiency in the non-native language. Here we explored how the degree of reliance on cross-language similarity (as measured by the cognate facilitation effect) together with other domain-general cognitive factors contribute to reading comprehension achievement in a non-native language at different stages of the learning process. We tested two groups of native speakers of Spanish learning English at elementary and intermediate levels in an academic context. A regression model approach showed that domain-general cognitive skills are good predictors of second language reading achievement independently of the level of proficiency. Critically, we found that individual differences in the degree of reliance on the native language predicted foreign language reading achievement, showing a markedly different pattern between proficiency groups. At lower levels of proficiency the cognate facilitation effect was positively related with reading achievement, while this relation became negative at intermediate levels of foreign language learning. We conclude that the link between native- and foreign-language lexical representations helps participants at initial stages of the learning process, whereas it is no longer the case at intermediate levels of proficiency, when reliance on cross-language similarity is inversely related to successful non-native reading achievement. Thus, at intermediate levels of proficiency strong and direct mappings from the non-native lexical forms to semantic concepts are needed to achieve good non-native reading comprehension, in line with the premises of current models of bilingual lexico-semantic organization.

The inhibitory control (IC) model proposes that language control plays an important role in suppressing cross-language interference within a bilingual individual's cross-language output. However, it may also play a role in dynamic interactive communication. Accordingly, the current study used the electroencephalogram (EEG) to simultaneously record neural oscillations from 13 paired unbalanced Chinese-English bilinguals during cooperative picture-naming in either first language (L1) or second language (L2) according to cues. We found that the speaker and listener achieved synchronization by inhibiting interference from the nontarget language (cross-language interference) and partner (interpersonal interference) through language control. Furthermore, the more the language control resources were used, the higher the level of neural synchronization. These findings indicate that language control is associated with neural synchronization of cross-language communication. Altogether, the IC model should highlight the role of language control in inhibiting not only cross-language interference but also interpersonal interference during dynamic cross-language communication.

When a speaker's auditory feedback is altered, he adapts for the perturbation by altering his own production, which demonstrates the role of auditory feedback in speech motor control. In the present study, we explored the role of auditory acuity and executive control in this process. Based on the DIVA model and the major cognitive control models, we expected that higher auditory acuity, and better executive control skills would predict larger adaptation to the alteration. Thirty-six Spanish native speakers performed an altered auditory feedback experiment, executive control (numerical Stroop, Simon and Flanker) tasks, and auditory acuity tasks (loudness, pitch, and melody pattern discrimination). In the altered feedback experiment, participants had to produce the pseudoword “pep” (/pep/) while perceiving their auditory feedback in real time through earphones. The auditory feedback was first unaltered and then progressively altered in F1 and F2 dimensions until maximal alteration (F1 −150 Hz; F2 +300 Hz). The normalized distance of maximal adaptation ranged from 4 to 137 Hz (median of 75 ± 36). The different measures of auditory acuity were significant predictors of adaptation, while individual measures of cognitive function skills (obtained from the executive control tasks) were not. Better auditory discriminators adapted more to the alteration. We conclude that adaptation to altered auditory feedback is very well-predicted by general auditory acuity, as suggested by the DIVA model. In line with the framework of motor-control models, no specific claim on the implication of executive resources in speech motor control can be made.

Evidence for interregional structural asymmetries has been previously reported for brain anatomic regions supporting well-described functional lateralization. Here, we aimed to investigate whether the two brain hemispheres demonstrate dissimilar general structural attributes implying different principles on information flow management. Common left hemisphere/right hemisphere structural network properties are estimated and compared for right-handed healthy human subjects and a nonhuman primate, by means of 3 different diffusion-weighted magnetic resonance imaging fiber tractography algorithms and a graph theory framework. In both the human and the nonhuman primate, the data support the conclusion that, in terms of the graph framework, the right hemisphere is significantly more efficient and interconnected than the left hemisphere, whereas the left hemisphere presents more central or indispensable regions for the whole-brain structural network than the right hemisphere. From our point of view, in terms of functional principles, this pattern could be related with the fact that the left hemisphere has a leading role for highly demanding specific process, such as language and motor actions, which may require dedicated specialized networks, whereas the right hemisphere has a leading role for more general process, such as integration tasks, which may require a more general level of interconnection.

The study explores interbrain neural coupling when interlocutors engage in a conversation whether it be in their native or nonnative language. To this end, electroencephalographic hyperscanning was used to study brain-to-brain phase synchronization during a two-person turn-taking verbal exchange with no visual contact, in either a native or a foreign language context. Results show that the coupling strength between brain signals is increased in both, the native language context and the foreign language context, specifically, in the alpha frequency band. A difference in brain-to speech entrainment to native and foreign languages is also shown. These results indicate that between brain similarities in the timing of neural activations and their spatial distributions change depending on the language code used. We argue that factors like linguistic alignment, joint attention and brain-entrainment to speech operate with a language-idiosyncratic neural configuration, modulating the alignment of neural activity between speakers and listeners. Other possible factors leading to the differential interbrain synchronization patterns as well as the potential features of brain-to-brain entrainment as a mechanism are briefly discussed. We concluded that linguistic context should be considered when addressing interpersonal communication. The findings here open doors to quantifying linguistic interactions.

The aim of this study was to identify differential global and local brain structural patterns in Dravet Syndrome (DS) patients as compared with a control subject group, using brain morphometry techniques which provide a quantitative whole-brain structural analysis that allows for specific patterns to be generalized across series of individuals. Nine patients with the diagnosis of DS that tested positive for mutation in the SCN1A gene and nine well-matched healthy controls were investigated using voxel brain nnorphometry (VBM), cortical thickness and cortical gyrification measurements. Global volume reductions of gray matter (GM) and white matter (WM) were related to DS. Local volume reductions corresponding to several white matter regions in brainstem, cerebellum, corpus callosum, corticospinal tracts and association fibers (left inferior fronto-occipital fasciculus and left uncinate fasciculus) were also found. Furthermore, DS showed a reduced cortical folding in the right precentral gyrus. The present findings describe DS-related brain structure abnormalities probably linked to the expression of the SCN1A mutation. (C) 2014 Elsevier B.V. All rights reserved.

Whether the neural mechanisms that underlie the processing of a second language in highly proficient late bilinguals (L2 late learners) are similar or not to those that underlie the processing of the first language (L1) is still an issue under debate. In this study, a group of late learners of Spanish whose native language is English and a group of Spanish monolinguals were compared while they read sentences, some of which contained syntactic violations. A brain complex network analysis approach was used to assess the time-varying topological properties of the functional networks extracted from the electro-encephalography (EEG) recording. Late L2 learners showed a lower degree of parallel information transfer and a slower propagation between regions of the brain functional networks while processing sentences containing a gender mismatch condition as compared with a standard sentence configuration. In contrast, no such differences between these conditions were detected in the Spanish monolinguals. This indicates that when a morphosyntactic language incongruence that does not exist in the native language is presented in the second language, the neural activation pattern is configured differently in highly proficient late bilinguals than in monolinguals. (C) 2015 Elsevier Ltd. All rights reserved.

Cooperation and competition are two ways of social interaction keys to life in society. Recent EEG-based hyperscanning studies reveal that cooperative and competitive interactions induce an increase in interbrain coupling. However, whether this interbrain coupling effect is just a reflection of inter-subject motor coordination or can also signal the type of social interaction is unknown. Here, we show that behavioral coordination and social interaction type can be distinguished according to the frequency of oscillation in which the brains are coupled. We use EEG to simultaneously measure the brain activity of pairs of subjects, while they were performing a visual cue-target task in a cooperative and competitive manner. Behavioral responses were quasi-simultaneous between subject pairs for both competitive and cooperative conditions, with faster average response times for the competitive condition. Concerning brain activity, we found increased interbrain coupling in theta band (3–7 Hz) during cooperation and competition, with stronger coupling during competitive interactions. This increase of interbrain theta coupling correlated with a decrease in reaction times of the dyads. Interestingly, we also found an increase in brain-to-brain coupling in gamma band (38–42 Hz) only during cooperative interactions. Unlike the theta coupling effect, the gamma interbrain coupling did not correlate with dyads’ reaction times. Taken together, these results suggest that theta interbrain coupling could be linked to motor coordination processes common to cooperative and competitive interactions, while gamma brain-to-brain coupling emerges as an electrophysiological marker of shared intentionality during cooperative interactions.

How the brain deals with more than one language and whether we need different or extra brain language sub-networks to support more than one language remain unanswered questions. Here, we investigate structural brain network differences between early bilinguals and monolinguals. Using diffusion-weighted MRI (DW-MRI) tractography techniques and a network-based statistic (NBS) procedure, we found two structural sub-networks more connected by white matter (WM) tracts in bilinguals than in monolinguals; confirming WM brain plasticity in bilinguals. One of these sub-networks comprises left frontal and parietal/temporal regions, while the other comprises left occipital and parietal/temporal regions and also the right superior frontal gyrus. Most of these regions have been related to language processing and monitoring; suggesting that bilinguals develop specialized language sub-networks to deal with the two languages. Additionally, a complex network analysis showed that these sub-networks are more graph-efficient in bilinguals than monolinguals and this increase seems to be at the expense of a whole-network graph-efficiency decrease. (C) 2013 Elsevier Inc. All rights reserved.

Neuronal oscillations play a key role in auditory perception of verbal input, with the oscillatory rhythms of the brain showing synchronization with specific frequencies of speech. Here we investigated the neural oscillatory patterns associated with perceiving native, foreign, and unknown speech. Spectral power and phase synchronization were compared to those of a silent context. Power synchronization to native speech was found in frequency ranges corresponding to the theta band, while no synchronization patterns were found for the foreign speech context and the unknown language context. For phase synchrony, the native and unknown languages showed higher synchronization in the theta-band than the foreign language when compared to the silent condition. These results suggest that neural synchronization patterns are markedly different for native and foreign languages. (C) 2015 Elsevier Inc. All rights reserved.

Rightward shifts in attention are a common consequence of brain injury. A growing body of evidence appears to suggest that increases in attentional load, and decreases in alertness can lead to rightward shifts in attention in healthy and patient populations. It is unclear however whether these factors affect spatial biases in attention at the level of preparatory control processes or at the level of stimulus driven expression mechanisms. Whilst such effects cannot easily be dissociated behaviourally, the robust association between changes in α-band activity and shifts in visual attention provides a neural marker by which the temporal dynamics of effects of attentional load on spatial processing might be examined. Here we use electroencephalography to examine the relationship between modulations in α-band activity and behavioural outcome on a dual task paradigm comprising a detection task (t1), closely followed by a temporal order judgment task (t2). We examine the effects of high (respond to t1 and t2) and low (t2 only) attentional load conditions on spatial bias and changes in lateralization of α-band activity over the course of the trial. As anticipated a rightward bias in detecting target onsets was observed in the temporal order judgment task (t2) under conditions of high attentional load. This rightward shift in attention was associated with changes in the lateralization of α-band activity that occurred only after the presentation of t2, suggesting that attentional load may primarily influence expression mechanisms.

Unagreement patterns consist in a person feature mismatch between subject and verb that is nonetheless grammatical in Spanish. The processing of this type of construction gives new insights into the understanding of agreement processes during language comprehension. Here, we contrasted oscillatory brain activity triggered by Unagreement in different EEG bands with those triggered by Standard Agreement and Person Mismatch sentences. In Spectral Power analysis, a similar pattern for Unagreement to that elicited by Person Mismatch was found in lower beta and alpha bands, approximately around 600 ms. This suggests that fast oscillations reflect the evaluation of the feature match between two structurally related constituents (independently of its grammaticality). In an equivalent time window, the Unagreement condition behaves similarly to the Standard Agreement condition in the theta band, but different from the Person Mismatch condition that shows an enhanced spectral power. In addition, an enhanced phase synchrony in lower beta frequency around 600 ms is associated to standard agreement patterns, while beta-high frequencies at 800 ms characterize processing of Unagreement sentences. These results support the functional dissociation between the evaluation of the feature match between two structurally related constituents (independently of its grammaticality in fast oscillatory bands) and integration of linguistic material in working memory (reflected by theta oscillations). Successful resolution of an agreement dependency is better reflected in phase synchronizations at beta band. (C) 2012 Elsevier Ltd. All rights reserved.

Evidence about high global and local parallel information processing between brain gray matter regions has being previously reported for different mammalian species (e.g. cat, monkey and humans). Here our goal is to study these characteristics but this time in mouse looking for other different mammalian species that shares this trait, which should be indicating similar brain structural growing organizational strategies shaped conveniently trough the evolutionary processes. Specifically, anatomical connections between 150 anatomic regions covering all the gray matter of healthy (C3HeB.FeJ, n = 5) mice were estimated by means of fiber tractography techniques based on high resolution Diffusion Weighted MRI data, and from the resultant information individual brain structural networks were created considering each brain region as a node that can be connected to any other node (region) depending of the obtained evidence supporting white matter fiber connections amount them. Then the created individual structural brain networks were analyzed attending to five different topological measures: clustering, mean path length, local efficiency, global efficiency and small-worldness index. The results reveals the small-word attributes of the structural network of the mouse brain, at the same time that confirms a smaller global efficiency and bigger local efficiency in comparison with the equivalent random networks, which in conjunction is in agreement with the previous studies on mammalian species. Considering that mouse animal models are of especial interest for biomedical research, in conjunction with the fact that current trends in human brain networks analyses are focused to detect topological network alterations associated to specific states of pathology, our methodology/findings could be of significant utility for the scientific community that employ the mouse animal model in the study of specific brain pathologies as well as their responds to different therapies.

Spoken word recognition models and phonological theory propose that abstract features play a central role in speech processing. It remains unknown, however, whether auditory cortex encodes linguistic features in a manner beyond the phonetic properties of the speech sounds themselves. We took advantage of the fact that English phonology functionally codes stops and fricatives as voiced or voiceless with two distinct phonetic cues: Fricatives use a spectral cue, whereas stops use a temporal cue. Evidence that these cues can be grouped together would indicate the disjunctive coding of distinct phonetic cues into a functionally defined abstract phonological feature. In English, the voicing feature, which distinguishes the consonants [s] and [t] from [z] and [d], respectively, is hypothesized to be specified only for voiceless consonants (e.g., [s t]). Here, participants listened to syllables in a many-to-one oddball design, while their EEG was recorded. In one block, both voiceless stops and fricatives were the standards. In the other block, both voiced stops and fricatives were the standards. A critical design element was the presence of intercategory variation within the standards. Therefore, a many-to-one relationship, which is necessary to elicit an MMN, existed only if the stop and fricative standards were grouped together. In addition to the ERPs, event-related spectral power was also analyzed. Results showed an MMN effect in the voiceless standards block-an asymmetric MMN-in a time window consistent with processing in auditory cortex, as well as increased prestimulus beta-band oscillatory power to voiceless standards. These findings suggest that (i) there is an auditory memory trace of the standards based on the shared [voiceless] feature, which is only functionally defined; (ii) voiced consonants are underspecified; and (iii) features can serve as a basis for predictive processing. Taken together, these results point toward auditory cortex's ability to functionally code distinct phonetic cues together and suggest that abstract features can be used to parse the continuous acoustic signal.

The neuropsychological impact of processing naturalistic speech streams containing code switches at the inter-sentential level was studied in fluent bilinguals who frequently switch between languages. To this end, electroencephalographic recordings (EEG) and a behavioral recall test were used to address speech perception while processing pieces of information conveyed in a single- or mixed-language speech carrier. Measurements of spectral power in the continuous EEG signal accompanying perception of speech were directly compared between conditions. The direction of the switch was also assessed. Our principal finding was a reduced oscillatory power in the beta frequencies when bilinguals are attentively listening to informative speech streams in which the two known languages are intermixed. The memory recall test showed equivalent performance across the different language conditions. These results suggest that the cognitive cost of processing speech containing inter-sentential language switches is reflected at a neural level but that it has no measurable impact on the recall of long streams of information. Listening speech in which the two languages known to a bilingual are mixed at a sentence level, may have no clear behavioral drawback, but implies some neural processing cost. •Proficient bilinguals show equivalent neural oscillatory activity associated to listening speech in the known languages.•Mixing two well-known languages yields a desynchronization of the oscillatory activity in the beta band.•L1.→L2 language switches increase theta activity as compared to switches L2→L1.•Inter-sentential language switching during speech perception has no evident impact on long-term memory recall.

Cambio hacia la derecha en los juicios de orden temporal durante el parpadeo atencional. El orden temporal de dos eventos, cada uno de ellos presentado en un hemicampo visual diferente, puede ser juzgado correctamente por observadores típicos inclusive cuando la diferencia de tiempo entre las presentaciones sea muy pequeña. El presente trabajo analiza la influencia de un proceso endógeno sobre el juicio de orden temporal (JOT) y nos muestra que la percepción del orden temporal está también afectada cuando los recursos atencionales disponibles son reducidos mediante un paradigma de parpadeo atencional (PA). A los participantes se les presentaron los siguientes estímulos: un primer estímulo visual (T1) en el centro de fijación y luego de un intervalo de tiempo variable (280 ó 1030 ms), un par de estímulos lateralizados (T2). Para la tarea dual con el intervalo de tiempo de 280 ms entre T1 y T2, la precisión en el JOT se deterioró, evidenciando un PA. Sin embargo, durante el PA en lugar de la asimetría favorable al lado izquierdo, aparece un significativo sesgo en contra de ese lado.

This study investigates the spatial bias of visual attention measured by a temporal order judgement (TOJ) task and the influence of a high attentional load condition in a group of dyslexic children compared to a control group with normal reading skills (each group N=10). The TOJ task (T2) was placed after a shape discrimination task (T1). In a low attentional load block participants worked only on T2, whereas in the high attentional load block they were required to process both T1 and T2. Several t-tests were executed to compare performance between conditions and groups. In the low attentional load conditions, results in dyslexic children were significantly impaired for the right visual field compared to a control group. The high attentional load conditions did not enhance these effects and seems to provoke the same leftward bias in the control group.

Neuroimaging classification procedures between normal and pathological subjects are sparse and highly dependent of an expert's clinical criterion. Here, we aimed to investigate whether possible brain structural network differences in the shiverer mouse mutant, a relevant animal model of myelin related diseases, can reflect intrinsic individual brain properties that allow the automatic discrimination between the shiverer and normal subjects. Common structural networks properties between shiverer (C3Fe.SWV Mbp shi /Mbp shi , n = 6) and background control (C3HeB.FeJ, n = 6) mice are estimated and compared by means of three diffusion weighted MRI (DW-MRI) fiber tractography algorithms and a graph framework. Firstly, we found that brain networks of control group are significantly more clustered, modularized, efficient and optimized than those of the shiverer group, which presented significantly increased characteristic path length. These results are in line with previous structural/functional complex brain networks analysis that have revealed topologic differences and brain network randomization associated to specific states of human brain pathology. In addition, by means of network measures spatial representations and discrimination analysis, we show that it is possible to classify with high accuracy to which group each subject belongs, providing also a probability value of being a normal or shiverer subject as an individual anatomical classifier. The obtained correct predictions (e.g., around 91.6–100%) and clear spatial subdivisions between control and shiverer mice, suggest that there might exist specific network subspaces corresponding to specific brain disorders, supporting also the point of view that complex brain network analyses constitutes promising tools in the future creation of interpretable imaging biomarkers.

During language comprehension, semantic contextual information is used to generate expectations about upcoming items. This has been commonly studied through the N400 event-related potential (ERP), as a measure of facilitated lexical retrieval. However, the associative relationships in multi-word expressions (MWE) may enable the generation of a categorical expectation, leading to lexical retrieval before target word onset. Processing of the target word would thus reflect a target-identification mechanism, possibly indexed by a P3 ERP component. However, given their time overlap (200–500 ms post-stimulus onset), differentiating between N400/P3 ERP responses (averaged over multiple linguistically variable trials) is problematic. In the present study, we analyzed EEG data from a previous experiment, which compared ERP responses to highly expected words that were placed either in a MWE or a regular non-fixed compositional context, and to low predictability controls. We focused on oscillatory dynamics and regression analyses, in order to dissociate between the two contexts by modeling the electrophysiological response as a function of item-level parameters. A significant interaction between word position and condition was found in the regression model for power in a theta range (~7–9 Hz), providing evidence for the presence of qualitative differences between conditions. Power levels within this band were lower for MWE than compositional contexts when the target word appeared later on in the sentence, confirming that in the former lexical retrieval would have taken place before word onset. On the other hand, gamma-power (~50–70 Hz) was also modulated by predictability of the item in all conditions, which is interpreted as an index of a similar “matching” sub-step for both types of contexts, binding an expected representation and the external input.

[Display omitted] Hyperscanning refers to obtaining simultaneous neural recordings from more than one person (Montage et al., 2002 [1]), that can be used to study interactive situations. In particular, hyperscanning with Electroencephalography (EEG) is becoming increasingly popular since it allows researchers to explore the interactive brain with a high temporal resolution. Notably, there is a 40-year gap between the first instance that simultaneous measurement of EEG activity was mentioned in the literature (Duane and Behrendt, 1965 [2]), and the first actual description of an EEG hyperscanning setup being implemented (Babiloni et al., 2006 [3]). To date, specific EEG hyperscanning devices have not yet been developed and EEG hyperscanning setups are not usually described with sufficient detail to be easily reproduced. Here, we offer a step-by-step description of solutions to many of these technological challenges. Specifically, we describe and provide customized implementations of EEG hyperscanning setups using hardware and software from different companies: Brain Products, ANT, EGI, and BioSemi. •Necessary details to set up a functioning EEG hyperscanning protocol are provided.•The setups allow independent measures and measures of synchronization between the signals of two different brains.•Individual electrical Ground and Reference is obtained in all discussed systems.

Currently, there is increasing attention on how to best improve language control efficiency and minimize cross-language interference in bilinguals. Previous studies have demonstrated that right dorsolateral prefrontal cortex (rDLPFC) plays an important role in inhibiting unrelated stimuli. The current study applied transcranial direct current stimulation (tDCS) during language switching to determine whether modulation of rDLPFC would affect language control mechanisms. All the participants have undergone three types of stimulations: cathodal stimulation, anodal stimulation and sham stimulation. The sequence of three stimulations was counterbalanced across participants. After each stimulation, participants performed picture naming task for language switching. Unbalanced bilinguals exhibited a larger late positive component (LPC) in switching to the weaker language than to the dominant one and similar L1 and L2 switch costs only in the cathodal tDCS (C-tDCS) session. Further analyses showed that the differences of switch costs (L1 switch costs – L2 switch costs) in the C-tDCS session were smaller than in the sham-tDCS (S-tDCS) session. Results were largely consistent with the assumption that cathodal stimulation improving inhibitory control abilities of unbalanced bilinguals to help them better inhibit interference. Another possibility is that cathodal stimulation also worked in other brain areas (e.g., supplementary motor area), which potentially altered unbalanced bilinguals’ speech planning or abilities to encode task sets.

Electroencephalographic hyperscanning was used to investigate interbrain synchronization patterns in dyads of participants interacting through speech. Results show that brain oscillations are synchronized between listener and speaker during oral narratives. This interpersonal synchronization is mediated in part by a lower-level sensory mechanism of speech-to-brain synchronization, but also by the interactive process that takes place in the situation per se. These results demonstrate the existence of brain-to-brain entrainment which is not merely an epiphenomenon of auditory processing, during listening to one speaker. The study highlights the validity of the two-person neuroscience framework for understanding induced brain activity, and suggests that verbal information exchange cannot be fully understood by examining the listener's or speaker's brain activity in isolation.

This study investigates the dynamics of speech envelope tracking during speech production, listening and selflistening. We use a paradigm in which participants listen to natural speech (Listening), produce natural speech (Speech Production), and listen to the playback of their own speech (Self-Listening), all while their neural activity is recorded with EEG. After time-locking EEG data collection and auditory recording and playback, we used a Gaussian copula mutual information measure to estimate the relationship between information content in the EEG and auditory signals. In the 2-10 Hz frequency range, we identified different latencies for maximal speech envelope tracking during speech production and speech perception. Maximal speech tracking takes place approximately 110 ms after auditory presentation during perception and 25 ms before vocalisation during speech production. These results describe a specific timeline for speech tracking in speakers and listeners in line with the idea of a speech chain and hence, delays in communication.

Grammatical agreement is a widespread language phenomenon that indicates formal syntactic relations between words; however, it also conveys basic lexical (e.g. grammatical gender) or semantic (e.g. numerosity) information about a discourse referent. In this study, we focus on the reading of Spanish noun phrases, violating either number or gender determiner–noun agreement compared to grammatical controls. Magnetoencephalographic activity time-locked to the onset of the noun in both types of violation revealed a left-lateralized brain network involving anterior temporal regions (~220ms) and, later in time, ventro-lateral prefrontal regions (>300ms). These activations coexist with dependency-specific effects: in an initial step (~170ms), occipito-temporal regions are employed for fine-grained analysis of the number marking (in Spanish, presence or absence of the suffix ‘-s’), while anterior temporal regions show increased activation for gender mismatches compared to grammatical controls. The semantic relevance of number agreement dependencies was mainly reflected by left superior temporal increased activity around 340ms. These findings offer a detailed perspective on the multi-level analyses involved in the initial computation of agreement dependencies, and theoretically support a derivational approach to agreement computation. •Derivational views on grammatical agreement assume feature-specific processing.•MEG here showed feature-specific effects for different agreement mismatches.•Left anterior temporal and later inferior frontal areas process agreement structures.•This network integrates dependency-specific processes from further left brain regions.•These data support a three-stage neurocognitive model of agreement processing.

Studies of inter-brain relationships thrive, and yet many reservations regarding their scope and interpretation of these phenomena have been raised by the scientific community. It is thus essential to establish common ground on methodological and conceptual definitions related to this topic and to open debate about any remaining points of uncertainty. We here offer insights to improve the conceptual clarity and empirical standards offered by social neuroscience studies of inter-personal interaction using hyperscanning with a particular focus on verbal communication.

The catalytic oxidation of aqueous crystal violet (CV) solutions was investigated using Ni and Fe catalysts supported over Mg–Al oxides synthesized by the autocombustion method. The influence of temperature, loading, and selectivity were studied in the catalytic wet air oxidation (CWAO) of CV. The kind of metal had an important contribution in the redox process as significant differences were observed between Fe, Ni, and their mixtures. The catalysts with only Fe as active phase were more efficient for the oxidation of CV under normal conditions (T = 25 °C and atmospheric pressure) compared to those containing Ni, revealing the influence of the transition metal on catalytic properties. It was found that iron-containing materials displayed enhanced textural properties. The synthesis of Fe/MgAl catalysts by the autocombustion method led to solids with excellent catalytic behavior, 100% CV degradation in eight hours of reaction, 68% selectivity to CO₂, and significant reduction of chemical oxygen demand (COD).

The catalytic oxidation of aqueous Crystal Violet (CV) solutions has been investigated using Ni and Fe catalysts supported over Mg-Al oxides synthetized by the auto-combustion method. The influence of temperature, loading and selectivity were studied in the catalytic wet air oxidation (CWAO) of CV. The kind of metal had an important contribution in the redox process, since significant differences between Fe, Ni and their mixtures were observed. The catalysts with only Fe as active phase were more efficient for the oxidation of CV under normal conditions (T = 25 °C and atmospheric pressure) compared to those containing Ni, revealing the influence of the transition metal on catalytic properties. It was found that iron containing materials displayed enhanced textural properties. The synthesis of Fe/MgAl catalysts by the auto-combustion method, leads to solids with excellent catalytic behavior, CV degradation of 100% in eight hours of reaction, 68% of selectivity to CO2 and significant reduction of COD (Chemical oxygen demand)

Dravet syndrome (DS) is an epilepsy of infantile onset, usually related to a mutation in gene sodium channel alpha 1 subunit, that leads to different typological seizures before the first year of life. Although most research has focused on the clinical description of the syndrome, some recent studies have focused on its impact on cognitive development, identifying both motor disorders and visual-processing deficits as basic factors affected in adults and children with DS. In this article, we designed a cross-sectional study to examine the cognitive phenotype of children affected by DS from a neurodevelopmental perspective. We report measures for both basic (auditory perception, visual and phonological processing, motor coordination) and higher order cognitive processes (verbal production, categorization, and executive function) in two age groups of DS children (M = 8.8 and M = 14.1) and control children of the same chronological age. Results showed an important cognitive delay in DS children with respect to controls in both basic and higher order cognitive abilities, with a better general outcome in tasks that required processing visual material (visual memory and categorization) than in tasks involving verbal material. In addition, performance of DS children in certain basic tasks (visual memory) correlated with performance on complex ones (categorization). These findings encourage promoting an early identification of not only clinical but also cognitive features in DS children from very early stages of development in order to optimize their neurodevelopmental outcome.