Over the last years, increasing evidence has fuelled the hypothesis that Autism Spectrum Disorder (ASD) is a condition of altered brain functional connectivity. The great majority of these empirical studies relies on functional magnetic resonance imaging (fMRI) which has a relatively poor temporal resolution. Only a handful of studies has examined networks emerging from dynamic coherence at the millisecond resolution and there are no investigations of coherence at the lowest frequencies in the power spectrum-which has recently been shown to reflect long-range cortico-cortical connections. Here we used electroencephalography (EEG) to assess dynamic brain connectivity in ASD focusing in the low-frequency (delta) range. We found that connectivity patterns were distinct in ASD and control populations and reflected a double dissociation: ASD subjects lacked long-range connections, with a most prominent deficit in fronto-occipital connections. Conversely, individuals with ASD showed increased short-range connections in lateral-frontal electrodes. This effect between categories showed a consistent parametric dependency: as ASD severity increased, short-range coherence was more pronounced and long-range coherence decreased. Theoretical arguments have been proposed arguing that distinct patterns of connectivity may result in networks with different efficiency in transmission of information. We show that the networks in ASD subjects have less Clustering coefficient, greater Characteristic Path Length than controls - indicating that the topology of the network departs from small-world behaviour - and greater modularity. Together these results show that delta-band coherence reveal qualitative and quantitative aspects associated with ASD pathology.

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.Running title: Brain networks in ASD are tuned for introspection.

Lack of access to services and support is an important issue for people with autism, but in low- and middle-income countries there is a lack of data on this problem. The aims of this study were to describe the challenges and priorities, identify barriers to care, and map stigma among families of individuals with autism in Latin America. This survey was undertaken by the Red Espectro Autista Latinoamerica network, a coalition of researchers/clinicians from six Latin American countries; it comprised 2942 caregivers of children with autism from Brazil, Argentina, Chile, Uruguay, Venezuela, and the Dominican-Republic, who completed the Spanish/Portuguese version of the Caregiver Needs Survey. The survey showed that the main priorities were greater community awareness and improvements in education. The main barriers to care were waiting lists (50.2%), treatment costs (35.2%), and lack of specialized services (26.1%). Stigma experienced by families was frequent: one-third reported feeling discriminated against and helpless for having a child with autism, 48.8% reported some type of financial problem, 47.4% had to reduce work hours, and 35.5% had to stop working because of their child’s autism. This survey describes the main needs/challenges faced by individuals with autism in Latin America, helping to build data-driven strategies at a national/regional level. Lay abstract Approximately 6 million individuals with autism spectrum disorder live in Latin America. In order to strengthen autism spectrum disorder research collaborations and awareness in the region, the Latin American Autism Spectrum Network ( Red Espectro Autista Latinoamerica) was constituted in 2015, comprising researchers and clinicians from the following six countries: Brazil Argentina, Chile, Uruguay, Venezuela, and the Dominican Republic. This first multisite study from the Red Espectro Autista Latinoamerica network aims to describe the challenges and priorities to identify barriers to care and to map stigma among families of individuals with autism spectrum disorder living in Latin America. A total of 2942 caregivers from these six countries completed an online survey showing that the main priorities were greater community awareness and improvements in the educational system for individuals with autism spectrum disorder. In addition to that, the main barriers to care were related to lack of structure, mainly waiting lists (50.2%), high treatment costs (35.2%), and lack of specialized services (26.1%). Stigma experienced by families was frequent: one third reported feeling discriminated against and helpless for having a child with autism spectrum disorder. Also, 48.8% of the caregivers declared financial problems, 47.4% of them had to cut down work hours, and 35.5% had to leave their jobs because of their child’s autism spectrum disorder. This is a pioneer study providing a description of the needs and challenges faced by families affected by autism spectrum disorder in Latin America, helping to build data-driven strategies at the national and regional levels.

BackgroundThe dimensional approach to autism spectrum disorder (ASD) considers ASD as the extreme of a dimension traversing through the entire population. We explored the potential utility of electroencephalography (EEG) functional connectivity as a biomarker. We hypothesized that individual differences in autistic traits of typical subjects would involve a long-range connectivity diminution within the delta band.MethodsResting-state EEG functional connectivity was measured for 74 neurotypical subjects. All participants also provided a questionnaire (Social Responsiveness Scale, SRS) that was completed by an informant who knows the participant in social settings. We conducted multivariate regression between the SRS score and functional connectivity in all EEG frequency bands. We explored modulations of network graph metrics characterizing the optimality of a network using the SRS score.ResultsOur results show a decay in functional connectivity mainly within the delta and theta bands (the lower part of the EEG spectrum) associated with an increasing number of autistic traits. When inspecting the impact of autistic traits on the global organization of the functional network, we found that the optimal properties of the network are inversely related to the number of autistic traits, suggesting that the autistic dimension, throughout the entire population, modulates the efficiency of functional brain networks.ConclusionsEEG functional connectivity at low frequencies and its associated network properties may be associated with some autistic traits in the general population.