State-dependent changes of connectivity patterns and functional brain network topology in Autism Spectrum Disorder

Anatomical and functional brain studies have converged to the hypothesis that Autism Spectrum Disorders (ASD) are associated with atypical connectivity. Using a modified resting-state paradigm to drive subjects' attention, we provide evidence of a very marked interaction between ASD brain functional connectivity and cognitive state. We show that functional connectivity changes in opposite ways in ASD and typicals as attention shifts from external world towards one's body generated information. Furthermore, ASD subject alter more markedly than typicals their connectivity across cognitive states. Using differences in brain connectivity across conditions, we classified ASD subjects at a performance around 80% while classification based on the connectivity patterns in any given cognitive state were close to chance. Connectivity between the Anterior Insula and dorsal-anterior Cingulate Cortex showed the highest classification accuracy and its strength increased with ASD severity. These results pave the path for diagnosis of mental pathologies based on functional brain networks obtained from a library of mental states

The ANTI-Vea task: analyzing the executive and arousal vigilance decrements while measuring the three attentional networks

This work was supported by the Spanish Ministry of Economy, Industry, and Competitiveness, research project to JL [grant number PSI2017-84926-P]; and by the Secretaría de Ciencia y Tecnología from the Universidad Nacional de Córdoba, Argentina (Proyecto Estimular to FGL); FGL received PhD scholarship support from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina; FGL received a scholarship mobility by the Asociación Universitaria Iberoamericana de Posgrado (AUIP) in cooperation with the Consejería de Economía y Conocimiento de la Junta de Andalucía, España; EMA was supported by a Juan de la Cierva postdoctoral fellowship from the Spanish Ministry of Economy, Industry, and Competitiveness [IJCI-2015-23204]. Preliminary results of this work has been presented in the Spanish XI Scientific Meeting of Attention (RECA), developed from 28th to 30th of September 2017 in Baeza, Spain. This paper is part of the doctoral thesis by the first author, under the supervision of the last two authors.The vigilance decrement phenomenon has been traditionally studied by simple and monotonous behavioral tasks. Nowadays, however, there is considerable interest in measuring vigilance with more complex tasks, including independent measures of other attentional functions. In the present study, we provide evidence supporting the suitability of the Attentional Networks Test for Interactions and Vigilance – executive and arousal components (ANTI-Vea) as an appropriate method to simultaneously assess multiple attentional and vigilance components. Vigilance was examined as two dissociated components: executive vigilance –as the detection of infrequent signals– and arousal vigilance –as the sustenance of a fast reaction to stimuli without response selection–. Importantly, the executive vigilance decrement was analyzed with a novel methodological approach to particularly determine whether the sensitivity loss effect is influenced by a floor level on the false alarms. As expected, the ANTI-Vea proved to be a task suitable to assess: (a) the main effects and interactions of phasic alertness, orienting, and executive control; (b) the executive vigilance decrement as a progressive change in the response bias; and (c) the arousal vigilance decrement as a progressive slowness and variability in reaction time. We discuss some critical theoretical and empirical implications of measuring vigilance components with the ANTI-Vea task. We expect the present study to provide a suitable method to analyze the vigilance decrement phenomenon when measuring multiple attentional and vigilance functions.Tradicionalmente, el decremento de la vigilancia se ha estudiado con tareas comportamentales simples y repetitivas. Sin embargo, actualmente existe un considerable interés en evaluar la vigilancia con tareas más complejas que incluyan medidas independientes de otros procesos atencionales. En el presente estudio, nuestro objetivo fue proporcionar nueva evidencia empírica sobre la adecuación del Test de Redes Atencionales para Interacciones y Vigilancia – componentes ejecutivo y de activación (ANTI-Vea) para medir simultáneamente múltiples componentes atencionales y de vigilancia. Examinamos la vigilancia como dos componentes disociados: vigilancia ejecutiva –como la detección de señales infrecuentes– y vigilancia de activación –como el mantenimiento de una reacción rápida a los estímulos sin control sobre la respuesta–. Es importante destacar que la vigilancia ejecutiva se analizó con un novedoso método para determinar si un efecto suelo en las falsas alarmas podría influenciar una disminución en la sensibilidad. Como se esperaba, se observó que la tarea ANTI-Vea es adecuada para medir: (a) los efectos principales e interacciones de las funciones de alerta fásica, orientación, y control ejecutivo; (b) el decremento en la vigilancia ejecutiva como un cambio en la tendencia de la respuesta; y (c) el decremento en la vigilancia de activación como un enlentecimiento y variabilidad de la respuesta. Discutimos algunas implicaciones teóricas y empíricas sobre la medición de los componentes de la vigilancia con la tarea ANTI-Vea. Esperamos que el presente estudio provea un método adecuado para analizar el decremento de la vigilancia cuando se evalúan múltiples funciones atencionales y de vigilancia.Spanish Ministry of Economy, Industry, and Competitiveness PSI2017-84926-PSecretaria de Ciencia y Tecnologia from the Universidad Nacional de Cordoba, ArgentinaConsejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET)Asociacion Universitaria Iberoamericana de Posgrado (AUIP)Junta de AndaluciaJuan de la Cierva postdoctoral fellowship from the Spanish Ministry of Economy, Industry, and Competitiveness IJCI-2015-2320

Cognitive load mitigates the executive but not the arousal vigilance decrement

This study was supported by the Spanish Ministry of Economy, Industry, and Competitiveness, through research projects to JL [grants number PSI2017-84926-P and PID2020-114790GB-I00] and the Secretaría de Ciencia y Tecnología from the Universidad Nacional de Córdoba, Argentina (Proyecto Estimular to FGL). In addition, FGL received PhD scholarship support from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina and a scholarship mobility by the Asociación Universitaria Iberoamericana de Posgrado (AUIP) in cooperation with the Consejería de Economía y Conocimiento de la Junta de Andalucía, España. Funding sources had no involvement in the study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. Preliminary results of this work has been presented in the Spanish XI Scientific Meeting of Attention (RECA), developed from 28th to 30th of September 2017 in Baeza, Spain. This study is part of the doctoral thesis by FGL, conducted under the supervision of JL and EMA.Previous research has shown opposite effects of dual tasking on the vigilance decrement phenomenon. We examined the executive (i.e., detecting infrequent critical signals) and arousal (i.e., sustaining a fast reaction to stimuli without much control on responses) vigilance decrements as a function of task load. Ninety-six participants performed either a single signal-detection (i.e., executive vigilance) task, a single reaction time (i.e., arousal vigilance) task, or a dual vigilance task with the same stimuli and procedure. All participants self-reported their fatigue’ state along the session. Exploratory analyses included data from a previous study with a triple task condition. Task load significantly modulated the executive but not the arousal vigilance decrement. Interestingly, the largest increase in mental fatigue was observed in the single executive vigilance task condition. We discuss limitations of classic vigilance theories to account for the vigilance decrement and changes in mental fatigue as a function of task load.Spanish Ministry of Economy, Industry, and Competitiveness, grants number PSI2017-84926-P and PID2020-114790GB-I00Secretaría de Ciencia y Tecnología from the Universidad Nacional de Córdoba, ArgentinaConsejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Asociación Universitaria Iberoamericana de Posgrado (AUIP) in cooperation with the Consejería de Economía y Conocimiento de la Junta de Andalucía, Españ

Collective behavior in the spatial spreading of obesity

Obesity prevalence is increasing in many countries at alarming levels. A difficulty in the conception of policies to reverse these trends is the identification of the drivers behind the obesity epidemics. Here, we implement a spatial spreading analysis to investigate whether obesity shows spatial correlations, revealing the effect of collective and global factors acting above individual choices. We find a regularity in the spatial fluctuations of their prevalence revealed by a pattern of scale-free long-range correlations. The fluctuations are anomalous, deviating in a fundamental way from the weaker correlations found in the underlying population distribution indicating the presence of collective behavior, i.e., individual habits may have negligible influence in shaping the patterns of spreading. Interestingly, we find the same scale-free correlations in economic activities associated with food production. These results motivate future interventions to investigate the causality of this relation providing guidance for the implementation of preventive health policies

Tract-based statistical analyzes in dMRI in autism spectrum disorder

International audienceIntroduction Recent studies show an atypical perceptive behavior on face processing in autism. Functional studies show that the fusiform gyrus is involved in face perception and is not or less activated in autistic subjects [1]. These face processing is believed to affect social interaction, which can be quantified by ADOS scores and related to the functionality of the prefrontal cortex. The aim of this study is to quantify anatomical changes in autistic subjects on the white matter tracts that traverse the fusiform gyrus, the prefrontal cortex and the superior temporal gyrus and correlate them with ADOS scores to complete. In this study, we first verified the connectivity difference between the fusiform gyrus, the prefrontal cortex and the superiotemporal gyrus through fMRI. Then, we used Diffusion Tensor MRI (DT) images to assess the integrity of automatically segmented white matter bundles connecting these girii. Finally, we perform statistical analysis on these fiber bundles using diffusivity measures calculated from DT to characterize tissue microstructure changes and correlate these changes with ADOS scores. Materials and methods Data acquisition. We acquired dMRI of eight adults with high-functioning autism or Asperger syndrome and eleven healthy adults at the University of Buenos Aires on a GE Signa Hdxt 3.0T scanner. The acquisition consisted in 80 directions with b=1000s/mm2 and 1 image with b=0s/mm2 with 1×1×1.3mm voxel size. Data preparation. We started by generating an unbiased template of the DT images and registering linearly and non-linearly all of the images to it. Then, we computed DT-based full brain tractography for every subject. Finally, we used the tools developed by Wassermann et al [2] to cluster fiber bundles and select the bundles traversing the fusiform gyrus. This gyrus was identified through the girii parcelation of the JHU atlas. We clustered these bundles across subjects extracting a set of population-obtained bundles (see for Fig 1 for an example). Data analysis. We applied the statistical analysis of Wassermann et al [3] for each population-obtained bundle, we calculated its tract-probability map (TPM) (see Fig.3 for an example) and skeletonized this map to obtain a bidimensional representation of each bundle. For each patient, we projected the measure of diffusivity (FA, axial or radial diffusivity) around the tract to their closest point on the skeleton and we average them with a weight according to the TPM. This produces two populations (one for autists and one for controls) of projected functions on the skeleton. For each tract and each measure, we used a cluster-based permutation hypothesis testing approach [4] to detect dissimilarities between both populations. For significant clusters, we calculated correlation between the mean diffusivity measure and ADOS scores. Results We found different clusters (Fig 1, red voxels) where there were dissimilarities between autistic and healthy subjects in FA measures on tracts traversing the fusiform gyrus in both hemispheres of the brain. We observed a reduction of FA values in a cluster (Fig 2, red voxels) on a bundle joined the superior temporal gyrus to the prefrontal cortex. In this cluster, the mean FA on the autistic subjects was strongly correlated with their scores to ADOS social interaction with a correlation coefficient lower than -0.96 a p-value lower than 0.004 (Fig3). Discussion First, results revealing difference between controls and autists in clusters on fiber bundle traversing the fusiform gyrus are in agreement with current literature giving this area as a classical area of face perception. Agreement reinforced by functional study of autists showing a drop of connectivity between the fusiform gyrus and the superior temporal cortex in comparison with controls (Fig 4). The localisation of the cluster where we founded a correlation with ADOS social interaction scores (Fig3) is in agreement with current anatomical literature, the superior temporal gyrus being a classical area of face perception and emotion and the prefrontal cortex a classical area of social interaction. This is reinforced by the strong inverse correlation showing that in this linking cluster a drop of FA value is strongly correlated by a rise of the intensity of autism. Our fMRI study (Fig 4) corroborates these statistical results, showing a drop of connectivity between the prefrontal cortex and the superior temporal gyrus. Disruption of white matter tracts between regions implicated in social functioning and face perception may contribute to increase the severity of autism

The presence of irrelevant alternatives paradoxically increases confidence in perceptual decisions

Confidence in perceptual decisions is thought to reflect the probability of being correct. According to this view, confidence should be unaffected or minimally reduced by the presence of irrelevant alternatives. To test this prediction, we designed five experiments. In Experiment 1, participants had to identify the largest geometrical shape among two or three alternatives. In the three-alternative condition, one of the shapes was much smaller than the other two, being a clearly incorrect option. Counter-intuitively, confidence was higher when the irrelevant alternative was present, evidencing that confidence construction is more complex than previously thought. Four computational models were tested, only one of them accounting for the results. This model predicts that confidence increases monotonically with the number of irrelevant alternatives, a prediction we tested in Experiment 2. In Experiment 3, we evaluated whether this effect replicated in a categorical task, but we did not find supporting evidence. Experiments 4 and 5 allowed us to discard stimuli presentation time as a factor driving the effect. Our findings suggest that confidence models cannot ignore the effect of multiple, possibly irrelevant alternatives to build a thorough understanding of confidence.Este documento es una versión del artículo que se encuentra publicado en Cognition, 234, 10537

Exploring the relationship between autism spectrum disorder traits and metacognition sensitivity

Given the large amounts of data that are currently acquired and manipulated, a new field called Computational Psychiatry has emerged. One of the best examples where computational psychiatry has contributed to neurodevelopmental syndromes comes from the study on Autism Spectrum Disorder (ASD). One of the current problems to which attention has recently begun to be paid is whether or not people with ASD have altered metacognition. The importance of exploring metacognition in ASD lies in practical and theoretical implications. However, the results found by studies exploring metacognition in people with ASD are inconsistent with each other. Only one study has utilized a bias-free measure of metacognition as in the present study. The main objective of this study was to contribute to the debate, through the study of metacognition in ASD traits in a sample of neurotypical people in an online experiment with a perceptual task. The results have not shown a statistically significant relationship between ASD traits and metacognition. These results are consistent with some of the previous studies.Sociedad Argentina de Informática e Investigación Operativ

Factoring the brain signatures of anesthesia concentration and level of arousal across individuals.

Combining resting-state functional magnetic resonance imaging (fMRI) connectivity and behavioral analysis during sedation, we factored out general effects of the anesthetic drug propofol and a specific index of conscious report, participants' level of responsiveness. The factorial analysis shows that increasing concentration of propofol in blood specifically decreases the connectivity strength of fronto-parietal cortical loops. In contrast, loss of responsiveness is indexed by a functional disconnection between the thalamus and the frontal cortex, balanced by an increase in connectivity strength of the thalamus to the occipital and temporal regions of the cortex