Event-related potential and lexical decision task in dyslexic adults: Lexical and lateralization effects.

Developmental dyslexia is a specific learning disorder that presents cognitive and neurobiological impairments related to different patterns of brain activation throughout development, continuing in adulthood. Lexical decision tasks, together with electroencephalography (EEG) measures that have great temporal precision, allow the capture of cognitive processes during the task, and can assist in the understanding of altered brain activation processes in adult dyslexics. High-density EEG allows the use of temporal analyses through event-related potentials (ERPs). The aim of this study was to compare and measure the pattern of ERPs in adults with developmental dyslexia and good readers, and to characterize and compare reading patterns between groups. Twenty university adults diagnosed with developmental dyslexia and 23 healthy adult readers paired with dyslexics participated in the study. The groups were assessed in tests of intelligence, phonological awareness, reading, and writing, as well as through the lexical decision test (LDT). During LDT, ERPs were recorded using a 128-channel EEG device. The ERPs P100 occipital, N170 occipito-temporal, N400 centro-parietal, and LPC centro-parietal were analyzed. The results showed a different cognitive profile between the groups in the reading, phonological awareness, and writing tests but not in the intelligence test. In addition, the brain activation pattern of the ERPs was different between the groups in terms of hemispheric lateralization, with higher amplitude of N170 in the dyslexia group in the right hemisphere and opposite pattern in the control group and specificities in relation to the items of the LDT, as the N400 were more negative in the Dyslexia group for words, while in the control group, this ERP was more pronounced in the pseudowords. These results are important for understanding different brain patterns in developmental dyslexia and can better guide future interventions according to the changes found in the profile.

Attention neuroenhancement through tDCS or neurofeedback: a randomized, single-blind, controlled trial.

Neurofeedback and transcranial Direct Current Stimulation (tDCS) are promising techniques for neuroenhancement of attentional performance. As far as we know no study compared both techniques on attentional performance in healthy participants. We compared tDCS and neurofeedback in a randomized, single-blind, controlled experiment assessing both behavioral (accuracy and time reaction) and electrophysiological (N1, P1, and P3 components) data of participants responding to the Attention Network Task (ANT). Eighty volunteers volunteered for this study. We adopted standard protocols for both techniques, i.e., a Sensorimotor Rhythm (SMR) protocol for neurofeedback and the right DLPFC anodal stimulation for tDCS, applied over nine sessions (two weeks). We did not find significant differences between treatment groups on ANT, neither at the behavioral nor at the electrophysiological levels. However, we found that participants from both neuromodulation groups, irrespective of if active or sham, reported attentional improvements in response to the treatment on a subjective scale. Our study adds another null result to the neuromodulation literature, showing that neurofeedback and tDCS effects are more complex than previously suggested and associated with placebo effect. More studies in neuroenhancement literature are necessary to fully comprehend neuromodulation mechanisms.

Neural correlates of sex differences in communicative gestures and speech comprehension: A preliminary study.

The goal of this study was to investigate whether the semantic processing of the audiovisual combination of communicative gestures with speech differs between men and women. We recorded event-related brain potentials in women and men during the presentation of communicative gestures that were either congruent or incongruent with the speech.Our results showed that incongruent gestures elicited an N400 effect over frontal sites compared to congruent ones in both groups. Moreover, the females showed an earlier N2 response to incongruent stimuli than congruent ones, while larger sustained negativity and late positivity in response to incongruent stimuli was observed only in males. These results suggest that women rapidly recognize and process audiovisual combinations of communicative gestures and speech (as early as 300 ms) whereas men analyze them at the later stages of the process.

Crossmodal processing of environmental sounds and everyday life actions: An ERP study.

To investigate the processing of environmental sounds, previous researchers have compared the semantic processing of words and sounds, yielding mixed results. This study aimed to specifically investigate the electrophysiological mechanism underlying the semantic processing of environmental sounds presented in a naturalistic visual scene. We recorded event-related brain potentials in a group of young adults over the presentation of everyday life actions that were either congruent or incongruent with environmental sounds. Our results showed that incongruent environmental sounds evoked both a P400 and an N400 effect, reflecting sensitivity to physical and semantic violations of environmental sounds' properties, respectively. In addition, our findings showed an enhanced late positivity in response to incongruous environmental sounds, probably reflecting additional reanalysis costs. In conclusion, these results indicate that the crossmodal processing of the environmental sounds might require the simultaneous involvement of different cognitive processes.

The electrophysiology of audiovisual processing in visual narratives in adolescents with autism spectrum disorder.

We investigated the semantic processing of the multimodal audiovisual combination of visual narratives with auditory descriptive words and auditory sounds in individuals with ASD. To this aim, we recorded ERPs to critical auditory words and sounds associated with events in visual narrative that were either semantically congruent or incongruent with the climactic visual event. A similar N400 effect was found both in adolescents with ASD and neurotypical adolescents (ages 9-16) when accessing different types of auditory information (i.e. words and sounds) into a visual narrative. This result might suggest that verbal information processing in ASD adolescents could be facilitated by direct association with meaningful visual information. In addition, we observed differences in scalp distribution of later brain responses between ASD and neurotypical adolescents. This finding might suggest ASD adolescents differ from neurotypical adolescents during the processing of the multimodal combination of visual narratives with auditory information at later stages of the process. In conclusion, the semantic processing of verbal information, typically impaired in individuals with ASD, can be facilitated when embedded into a meaningful visual information.

Electrophysiological indexes of ToM and non-ToM humor in healthy adults.

The cognitive processes involved in humor comprehension were analyzed by directly comparing the time course of brain activity associated with the perception of slapstick humor and that associated with the comprehension of humor requiring theory of mind (ToM). Four different comic strips (strips containing humorous scenes that required ToM, non-ToM humorous strips, non-humorous semantically coherent strips and non-humorous semantically incoherent strips) were presented to participants, while their EEG response was recorded. Results showed that both of the humorous comic strips and the semantically incongruent strip elicited an N400 effect, suggesting similar cognitive mechanisms underlying the processing of incongruent and humorous comic strips. The results also showed that the humorous ToM strips elicited a frontal late positive (LP) response, possibly reflecting the active deployment of ToM abilities such as perspective-taking and empathy that allow for the resolution and interpretation of apparently incongruent situations. In addition, the LP response was positively correlated with ratings of perceived amusement as well as individual empathy scores, suggesting that the increased LP response to ToM humorous strips reflects the combined activation of neural mechanisms involved in the experience of amusement and ToM abilities. Overall, humor comprehension appears to demand distinct cognitive steps such as the detection of incongruent semantic components, the construction of semantic coherence, and the appreciation of humoristic elements such as maladaptive emotional reactions. Our results show that the deployment of these distinct cognitive steps is at least partially dependent on individual empathic abilities.

Visual and Verbal Narrative Comprehension in Children and Adolescents with Autism Spectrum Disorders: An ERP Study.

We examined semantic processing in ASD children by presenting sentences with congruent or incongruent final words and visual narratives with congruent or incongruent final panels. An N400 effect to incongruent words appeared as compared to congruent ones, which was attenuated for the ASD children. We observed a negativity sustained to incongruous than congruous words, but only for the TD children. Incongruent panels evoked a greater fronto-central N400 amplitude than congruent panels in both groups. In addition, incongruent panels evoked a centro-parietal late positivity, only in controls. In conclusion, ASD children face processing deficits in both verbal and visual materials when integrating meaning across information, though such impairments may arise in different parts of the interpretive process, depending on the modality.

Anodal transcranial direct current stimulation of MPFC enhances humor processing.

The purpose of this study was to investigate whether the comprehension of a specific type of humorous situation requires the involvement of brain regions associated to mentalization or Theory of Mind processing and if the electrical stimulation of these areas would facilitate the comprehension of humor. To this aim, we analyzed the effects of tDCS stimulation on the MPFC and rTPJ during the presentation of humorous and non-humorous comic strips. In particular, the stimulus set included strips containing humorous scenes that required ToM abilities in order to be comprehended (Humorous ToM), non-ToM humorous strips (Humorous non-ToM), non-humorous strips which were semantically coherent but not funny (Congruent), and non-humorous strips which were semantically incoherent (Incongruent). Results suggest that the MPFC appears to be involved in both humor processing and in the incongruity resolution process: MPFC stimulation improved the ability to identify a non-humorous incongruent element and to recognize the humorous element of the scene. On the other hand, RTPJ activity doesn't seem to be specifically involved in humorous processing network and appears to be more related to the ability to understand the cognitive element of a social context.

The effect of cathodal tDCS on fear extinction: A cross-measures study.

BACKGROUND: Extinction-based procedures are often used to inhibit maladaptive fear responses. However, because extinction procedures show efficacy limitations, transcranial direct current stimulation (tDCS) has been suggested as a promising add-on enhancer. OBJECTIVE: In this study, we tested how cathodal tDCS over the right dorsolateral prefrontal cortex affects extinction and tried to unveil the processes at play that boost the effectiveness of extinction procedures and its translational potential to the treatment of anxiety disorders. METHODS: We implemented a fear conditioning paradigm whereby 41 healthy women (mean age = 20.51 ± 5.0) were assigned to either cathodal tDCS (n = 27) or sham tDCS (n = 16). Fear responses were measured with self-reports, autonomic responses, and implicit avoidance tendencies. RESULTS: Cathodal tDCS shows no statistically significant effect in extinction, according to self-reports, and seems to even negatively affect fear conditioned skin conductance responses. However, one to three months after the tDCS session and extinction, we found a group difference in the action tendencies towards the neutral stimuli (F (1, 41) = 12.04, p = .001, ηp2 = .227), with the cathodal tDCS group (as opposed to the sham group) showing a safety learning (a positive bias towards the CS-), with a moderate effect size. This suggests that cathodal tDCS may foster stimuli discrimination, leading to a decreased generalization effect. DISCUSSION: Cathodal tDCS may have enhanced long-term distinctiveness between threatening cues and perceptively similar neutral cues through a disambiguation process of the value of the neutral stimuli-a therapeutic target in anxiety disorders. Future studies should confirm these results and extend the study of cathodal tDCS effect on short term avoidance tendencies.

Listening beyond seeing: Event-related potentials to audiovisual processing in visual narrative.

Every day we integrate meaningful information coming from different sensory modalities, and previous work has debated whether conceptual knowledge is represented in modality-specific neural stores specialized for specific types of information, and/or in an amodal, shared system. In the current study, we investigated semantic processing through a cross-modal paradigm which asked whether auditory semantic processing could be modulated by the constraints of context built up across a meaningful visual narrative sequence. We recorded event-related brain potentials (ERPs) to auditory words and sounds associated to events in visual narratives-i.e., seeing images of someone spitting while hearing either a word (Spitting!) or a sound (the sound of spitting)-which were either semantically congruent or incongruent with the climactic visual event. Our results showed that both incongruent sounds and words evoked an N400 effect, however, the distribution of the N400 effect to words (centro-parietal) differed from that of sounds (frontal). In addition, words had an earlier latency N400 than sounds. Despite these differences, a sustained late frontal negativity followed the N400s and did not differ between modalities. These results support the idea that semantic memory balances a distributed cortical network accessible from multiple modalities, yet also engages amodal processing insensitive to specific modalities.

Medial prefrontal cortex stimulation modulates irony processing as indexed by the N400.

In this study, we investigated whether the ERP responses observed during a verbal irony comprehension task might represent the cortical manifestation of the Medial Prefrontal Cortex (MPFC) activity. We performed a tDCS-EEG study in which we analyzed the effects of tDCS polarities (anode, cathode, sham) over the MPFC during a verbal irony task. We presented visual short stories portraying everyday situations followed by written statements in either an ironic or literal condition, whose meaning was referred to in the previous context. We manipulated the valence of the stimuli by presenting positive sentences or negative sentences in the ironic and literal conditions. The results revealed that the participants who received the anodal stimulation showed no differences in the N400 amplitude in response to the literal and the ironic condition. This could suggest that anodal stimulation has modulatory effects on N400 responses during irony comprehension. Our results indicated that the MPFC might be critical in accessing ironic information at the initial stage of irony comprehension. Finally, we found that the ironic compliments were more difficult to understand compared to the literal ones, suggesting that irony comprehension is affected by the valence of the information presented.

Non-invasive brain stimulation and computational models in post-stroke aphasic patients: single session of transcranial magnetic stimulation and transcranial direct current stimulation. A randomized clinical trial.

CONTEXT AND OBJECTIVE: Patients undergoing the same neuromodulation protocol may present different responses. Computational models may help in understanding such differences. The aims of this study were, firstly, to compare the performance of aphasic patients in naming tasks before and after one session of transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS) and sham, and analyze the results between these neuromodulation techniques; and secondly, through computational model on the cortex and surrounding tissues, to assess current flow distribution and responses among patients who received tDCS and presented different levels of results from naming tasks. DESIGN AND SETTING: Prospective, descriptive, qualitative and quantitative, double blind, randomized and placebo-controlled study conducted at Faculdade de Ciências Médicas da Santa Casa de São Paulo. METHODS: Patients with aphasia received one session of tDCS, TMS or sham stimulation. The time taken to name pictures and the response time were evaluated before and after neuromodulation. Selected patients from the first intervention underwent a computational model stimulation procedure that simulated tDCS. RESULTS: The results did not indicate any statistically significant differences from before to after the stimulation.The computational models showed different current flow distributions. CONCLUSIONS: The present study did not show any statistically significant difference between tDCS, TMS and sham stimulation regarding naming tasks. The patients'responses to the computational model showed different patterns of current distribution.

Non-invasive brain stimulation and computational models in post-stroke aphasic patients: single session of transcranial magnetic stimulation and transcranial direct current stimulation. A randomized clinical trial

ABSTRACT CONTEXT AND OBJECTIVE: Patients undergoing the same neuromodulation protocol may present different responses. Computational models may help in understanding such differences. The aims of this study were, firstly, to compare the performance of aphasic patients in naming tasks before and after one session of transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS) and sham, and analyze the results between these neuromodulation techniques; and secondly, through computational model on the cortex and surrounding tissues, to assess current flow distribution and responses among patients who received tDCS and presented different levels of results from naming tasks. DESIGN AND SETTING: Prospective, descriptive, qualitative and quantitative, double blind, randomized and placebo-controlled study conducted at Faculdade de Ciências Médicas da Santa Casa de São Paulo. METHODS: Patients with aphasia received one session of tDCS, TMS or sham stimulation. The time taken to name pictures and the response time were evaluated before and after neuromodulation. Selected patients from the first intervention underwent a computational model stimulation procedure that simulated tDCS. RESULTS: The results did not indicate any statistically significant differences from before to after the stimulation.The computational models showed different current flow distributions. CONCLUSIONS: The present study did not show any statistically significant difference between tDCS, TMS and sham stimulation regarding naming tasks. The patients'responses to the computational model showed different patterns of current distribution.

Ostracism via virtual chat room-Effects on basic needs, anger and pain.

Ostracism is characterized by a social pain provoked by being excluded and ignored. In order to address the effects of social ostracism in virtual non-physical interactions, we developed a more realistic paradigm as an alternative to Cyberball and assessed its effects on participant's expression of basic social needs, emotional experience and painful feeling. The chat room consisted of controlled social dialogue interactions between participants and two other (confederate) chat room partners. Exclusion was manipulated by varying the number of messages a participant received (15% and 33% in exclusion and inclusion, respectively). Analysis of participant (N = 54) responses revealed that exclusion induced a lower experience of basic-need states and greater anger, compared with included participants. In addition, excluded participants reported higher levels of two specific self-pain feelings, namely tortured and hurt. Our findings suggest that this procedure is effective in inducing social ostracism in a realistic and yet highly controlled experimental procedure.

tDCS application over the STG improves the ability to recognize and appreciate elements involved in humor processing.

The superior temporal gyrus (STG) has been found to play a crucial role in the recognition of actions and facial expressions and may, therefore, be critical for the processing of humorous information. Here we investigated whether tDCS application to the STG would modulate the ability to recognize and appreciate the comic element in serious and comedic situations of misfortune. To this aim, the effects of different types of tDCS stimulation on the STG were analyzed during a task in which the participants were instructed to categorize various misfortunate situations as "comic" or "not comic". Participants underwent three different tDCS conditions: Anodal-right/Cathodal-left; Cathodal-right/Anodal-left; Sham. Images depicting people involved in accidents were grouped into three categories based on the facial expression of the victim: angry or painful (Affective); bewildered and funny (Comic); and images that did not contain the victim's face (No Face). An improvement in mean reaction times in response to both the Comic and No Face stimuli was observed following Anodal-left/Cathodal-right stimulation when compared to sham stimulation. This suggests that this stimulation type reduced the reaction times to socio-emotional complex scenes, regardless of facial expression. The Anodal-right/Cathodal-left stimulation reduced the mean reaction times for Comic stimuli only, suggesting that specifically the right STG may be involved in facial expression recognition and in the appreciation of the comic element in misfortunate situations. These results suggest a functional hemispheric asymmetry in STG response to social stimuli: the left STG might have a role in a general comprehension of social complex situations, while the right STG may be involved in the ability to recognize and integrate specific emotional aspects in a complex scene.

Human biological and nonbiological point-light movements: Creation and validation of the dataset.

Human action perception is so powerful that people can identify movement efficiently in the absence of pictorial information, such as in point-light displays. Interest is growing in this type of stimulus for research in neuroscience. This interest stems from the advantage of separating the component of pure human action kinematics from other pictorial information, such as facial expression and muscle contraction. Although several groups have previously developed datasets of human point-light actions, due to the lack of datasets composed of daily actions with short durations, we developed 20 biological and 40 control (scrambled) point-light movements by using the technique of recording people wearing reflector patches. The videos are about 1 s long. Subsequently, we performed a judgment task in which 100 participants (50 male and 50 female) evaluated each video according to three categories: human action resemblance, performed action, and gender of actor. We present the mean scores of each evaluation for each video, and further propose a selection of the most suitable videos to be used as human point-light action displays and scrambled point-light displays for control. Finally, we discuss our findings on the gender attributions of the point-light displays.

Taking it easy when playing ultimatum game with a Down syndrome proposer: Effects on behavior and medial frontal negativity.

The ultimatum game (UG) is an endowment sharing game in which a proposer suggests a division of an asset to a recipient, who must accept or reject it. Economic studies showed that despite recipients usually rejecting unfair offers, perception and reaction to unfairness are highly dependent on who is the proposer. Event-related potentials (ERPs) commonly detected in UG games are the medial frontal negativity (MFN), a component detected in recipients facing unfair offers, and the P300, a component related to attentional and memory processes. Given this, we aimed to investigate the behavioral and ERP responses of healthy people playing the UG game with Down syndrome (DS) and typical development (TD) proposers. Nineteen subjects participated in this study. The UG behavioral data were similar to previous studies. ERP analysis showed no MFN in participants facing unfair offers. A higher P300 amplitude was detected when participants faced fair offers from TD compared to DS fair offers. We also found a positive correlation between P300 amplitude for TD offers and self-esteem scale score. Together these findings indicate that insertion of an atypical player in the UG led to changes in participants' perception and expectancy of the game.