Is functional brain connectivity atypical in autism? A systematic review of EEG and MEG studies

Background Although it is well recognized that autism is associated with altered patterns of over-and under-connectivity, specifics are still a matter of debate. Little has been done so far to synthesize available literature using whole-brain electroencephalography (EEG) and magnetoencephalography (MEG) recordings. Objectives 1) To systematically review the literature on EEG/MEG functional and effective connectivity in autism spectrum disorder (ASD), 2) to synthesize and critically appraise findings related with the hypothesis that ASD is characterized by long-range underconnectivity and local overconnectivity, and 3) to provide, based on the literature, an analysis of tentative factors that are likely to mediate association between ASD and atypical connectivity (e.g., development, topography, lateralization). Methods Literature reviews were done using PubMed and PsychInfo databases. Abstracts were screened, and only relevant articles were analyzed based on the objectives of this paper. Special attention was paid to the methodological characteristics that could have created variability in outcomes reported between studies. Results Our synthesis provides relatively strong support for long-range underconnectivity in ASD, whereas the status of local connectivity remains unclear. This observation was also mirrored by a similar relationship with lower frequencies being often associated with underconnectivity and higher frequencies being associated with both under-and over-connectivity. Putting together these observations, we propose that ASD is characterized by a general trend toward an under-expression of lower-band wide-spread integrative processes compensated by more focal, higher-frequency, locally specialized, and segregated processes. Further investigation is, however, needed to corroborate the conclusion and its generalizability across different tasks. Of note, abnormal lateralization in ASD, specifically an elevated left-over-right EEG and MEG functional connectivity ratio, has been also reported consistently across studies. Conclusions The large variability in study samples and methodology makes a systematic quantitative analysis (i.e. meta-analysis) of this body of research impossible. Nevertheless, a general trend supporting the hypothesis of long-range functional underconnectivity can be observed. Further research is necessary to more confidently determine the status of the hypothesis of short-range overconnectivity. Frequency-band specific patterns and their relationships with known symptoms of autism also need to be further clarified

Impact evaluation report: Egypt’s Takaful Cash Transfer Program: Second round report

Egypt introduced the Takaful and Karama Program (TKP), a pair of targeted cash transfer schemes in 2015. In 2018, the International Food Policy Research Institute (IFPRI) completed the first round of impact evaluation of TKP, based on household survey data collected after the first 15 months of the program. In the period between the first-round evaluation and the data collection for this report in January 2022, Egypt faced an enormous economic shock in the COVID-19 pandemic with a complete loss of tourism, which before the crisis was responsible for 12% of GDP and 10% of employment (IMF, 2021). A follow-up evaluation was designed to assess whether impacts estimated from the first round have been sustained and whether longer duration of treatment has led to impacts on additional outcome variables. This follow-up impact evaluation was conducted using a regression discontinuity (RD) design similar to the first round but using a different sample of households much more tightly concentrated around the 4500 thresholds to address concerns about the smaller discontinuity. We find that households invested in assets, particularly productive assets and Takaful households reduced their debt burdens. There were no measurable impacts of the Takaful program on household consumption or poverty, which may be partially explained by changes in household demographics. We also find that Takaful improved school enrollment and attendance and contributed to household’s ability to cope with shocks

Autism diagnosis differentiates neurophysiological responses to faces in adults with tuberous sclerosis complex

- Background: Autism spectrum disorder (ASD) is a common and highly heritable neurodevelopmental disorder that is likely to be the outcome of complex aetiological mechanisms. One strategy to provide insight is to study ASD within tuberous sclerosis complex (TSC), a rare disorder with a high incidence of ASD, but for which the genetic cause is determined. Individuals with ASD consistently demonstrate face processing impairments, but these have not been examined in adults with TSC using event-related potentials (ERPs) that are able to capture distinct temporal stages of processing. - Methods: For adults with TSC (n = 14), 6 of which had a diagnosis of ASD, and control adults (n = 13) passively viewed upright and inverted human faces with direct or averted gaze, with concurrent EEG recording. Amplitude and latency of the P1 and N170 ERPs were measured. - Results: Individuals with TSC + ASD exhibited longer N170 latencies to faces compared to typical adults. Typical adults and adults with TSC-only exhibited longer N170 latency to inverted versus upright faces, whereas individuals with TSC + ASD did not show latency differences according to face orientation. In addition, individuals with TSC + ASD showed increased N170 latency to averted compared to direct gaze, which was not demonstrated in typical adults. A reduced lateralization was shown for the TSC + ASD groups on P1 and N170 amplitude. - Conclusions: The findings suggest that individuals with TSC + ASD may have similar electrophysiological abnormalities to idiopathic ASD and are suggestive of developmental delay. Identifying brain-based markers of ASD that are similar in TSC and idiopathic cases is likely to help elucidate the risk pathways to ASD

The relationship between sensory sensitivity and autistic traits in the general population.

Individuals with Autism Spectrum Disorders (ASDs) tend to have sensory processing difficulties (Baranek et al. in J Child Psychol Psychiatry 47:591–601, 2006). These difficulties include over- and under-responsiveness to sensory stimuli, and problems modulating sensory input (Ben-Sasson et al. in J Autism Dev Disorders 39:1–11, 2009). As those with ASD exist at the extreme end of a continuum of autistic traits that is also evident in the general population, we investigated the link between ASD and sensory sensitivity in the general population by administering two questionnaires online to 212 adult participants. Results showed a highly significant positive correlation (r = .775, p < .001) between number of autistic traits and the frequency of sensory processing problems. These data suggest a strong link between sensory processing and autistic traits in the general population, which in turn potentially implicates sensory processing problems in social interaction difficulties

Atypical processing of gaze cues and faces explains comorbidity between autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD)

This study investigated the neurobiological basis of comorbidity between autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD). We compared children with ASD, ADHD or ADHD+ASD and typically developing controls (CTRL) on behavioural and electrophysiological correlates of gaze cue and face processing. We measured effects of ASD, ADHD and their interaction on the EDAN, an ERP marker of orienting visual attention towards a spatially cued location and the N170, a right-hemisphere lateralised ERP linked to face processing. We identified atypical gaze cue and face processing in children with ASD and ADHD+ASD compared with the ADHD and CTRL groups. The findings indicate a neurobiological basis for the presence of comorbid ASD symptoms in ADHD. Further research using larger samples is needed

Atypical disengagement from faces and its modulation by the control of eye fixation in children with Autism Spectrum Disorder

By using the gap overlap task, we investigated disengagement from faces and objects in children (9–17 years old) with and without autism spectrum disorder (ASD) and its neurophysiological correlates. In typically developing (TD) children, faces elicited larger gap effect, an index of attentional engagement, and larger saccade-related event-related potentials (ERPs), compared to objects. In children with ASD, by contrast, neither gap effect nor ERPs differ between faces and objects. Follow-up experiments demonstrated that instructed fixation on the eyes induces larger gap effect for faces in children with ASD, whereas instructed fixation on the mouth can disrupt larger gap effect in TD children. These results suggest a critical role of eye fixation on attentional engagement to faces in both groups

Quenching of acoustic bandgaps by flow noise

Copyright (2009) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics along with the following message: The following article appeared in Appl. Phys. Lett. 94, 134104 (2009) and may be found at http://dx.doi.org/10.1063/1.3111797. Authors own version of final article on e-print serversWe report an experimental study of acoustic effects produced by wind impinging on noise barriers based on two-dimensional sonic crystals with square symmetry. We found that the attenuation strength of sonic-crystal bandgaps decreases for increasing values of flow speed. A quenching of the acoustic bandgap appears at a certain speed value that depends of the barrier filling ratio. For increasing values of flow speed, the data indicate that the barrier becomes a sound source because of its interaction with the wind. We conclude that flow noise should be taken into account in designing acoustic barriers based on sonic crystals.This work was supported by the Spanish Agency of International Cooperation (AECI), the Spanish Ministry of Science and Innovation (MICIIN), and the Spanish Ministry of Public Works (MF). J.S.-D. acknowledges useful conversations with A. Broatch.Elnady, T.; Elsabbagh, A.; Akl, W.; Mohamady, O.; Garcia Chocano, VM.; Torrent Martí, D.; Cervera Moreno, FS.... (2009). Quenching of acoustic bandgaps by flow noise. Applied Physics Letters. 94(13). doi:10.1063/1.3111797S9413Sánchez-Pérez, J. V., Caballero, D., Mártinez-Sala, R., Rubio, C., Sánchez-Dehesa, J., Meseguer, F., … Gálvez, F. (1998). Sound Attenuation by a Two-Dimensional Array of Rigid Cylinders. Physical Review Letters, 80(24), 5325-5328. doi:10.1103/physrevlett.80.5325Rubio, C., Caballero, D., Sanchez-Perez, J. V., Martinez-Sala, R., Sanchez-Dehesa, J., Meseguer, F., & Cervera, F. (1999). The existence of full gaps and deaf bands in two-dimensional sonic crystals. Journal of Lightwave Technology, 17(11), 2202-2207. doi:10.1109/50.803012Caballero, D., Sánchez-Dehesa, J., Rubio, C., Mártinez-Sala, R., Sánchez-Pérez, J. V., Meseguer, F., & Llinares, J. (1999). Large two-dimensional sonic band gaps. Physical Review E, 60(6), R6316-R6319. doi:10.1103/physreve.60.r6316Caballero, D., Sánchez-Dehesa, J., Martínez-Sala, R., Rubio, C., Sánchez-Pérez, J. V., Sanchis, L., & Meseguer, F. (2001). Suzuki phase in two-dimensional sonic crystals. Physical Review B, 64(6). doi:10.1103/physrevb.64.064303Chen, Y.-Y., & Ye, Z. (2001). Acoustic Attenuation by Two-Dimensional Arrays of Rigid Cylinders. Physical Review Letters, 87(18). doi:10.1103/physrevlett.87.184301Sanchez-Perez, J. V., Rubio, C., Martinez-Sala, R., Sanchez-Grandia, R., & Gomez, V. (2002). Acoustic barriers based on periodic arrays of scatterers. Applied Physics Letters, 81(27), 5240-5242. doi:10.1063/1.1533112Goffaux, C., Maseri, F., Vasseur, J. O., Djafari-Rouhani, B., & Lambin, P. (2003). Measurements and calculations of the sound attenuation by a phononic band gap structure suitable for an insulating partition application. Applied Physics Letters, 83(2), 281-283. doi:10.1063/1.1592016Goffaux, C., & Vigneron, J. P. (2001). Theoretical study of a tunable phononic band gap system. Physical Review B, 64(7). doi:10.1103/physrevb.64.075118Zhong, L., Wu, F., Zhang, X., Zhong, H., & Zhong, S. (2005). Effects of orientation and symmetry of rods on the complete acoustic band gap in two-dimensional periodic solid/gas systems. Physics Letters A, 339(1-2), 164-170. doi:10.1016/j.physleta.2005.03.025Umnova, O., Attenborough, K., & Linton, C. M. (2006). Effects of porous covering on sound attenuation by periodic arrays of cylinders. The Journal of the Acoustical Society of America, 119(1), 278-284. doi:10.1121/1.2133715Martínez-Sala, R., Rubio, C., García-Raffi, L. M., Sánchez-Pérez, J. V., Sánchez-Pérez, E. A., & Llinares, J. (2006). Control of noise by trees arranged like sonic crystals. Journal of Sound and Vibration, 291(1-2), 100-106. doi:10.1016/j.jsv.2005.05.030Sanchis, L., Håkansson, A., Cervera, F., & Sánchez-Dehesa, J. (2003). Acoustic interferometers based on two-dimensional arrays of rigid cylinders in air. Physical Review B, 67(3). doi:10.1103/physrevb.67.03542

Profiling allele-specific gene expression in brains from individuals with autism spectrum disorder reveals preferential minor allele usage.

One fundamental but understudied mechanism of gene regulation in disease is allele-specific expression (ASE), the preferential expression of one allele. We leveraged RNA-sequencing data from human brain to assess ASE in autism spectrum disorder (ASD). When ASE is observed in ASD, the allele with lower population frequency (minor allele) is preferentially more highly expressed than the major allele, opposite to the canonical pattern. Importantly, genes showing ASE in ASD are enriched in those downregulated in ASD postmortem brains and in genes harboring de novo mutations in ASD. Two regions, 14q32 and 15q11, containing all known orphan C/D box small nucleolar RNAs (snoRNAs), are particularly enriched in shifts to higher minor allele expression. We demonstrate that this allele shifting enhances snoRNA-targeted splicing changes in ASD-related target genes in idiopathic ASD and 15q11-q13 duplication syndrome. Together, these results implicate allelic imbalance and dysregulation of orphan C/D box snoRNAs in ASD pathogenesis

Reduced preference for social rewards in a novel tablet based task in young children with Autism Spectrum Disorders

Atypical responsivity to social rewards has been observed in young children with or at risk of Autism Spectrum Disorders (ASD). These observations contributed to the hypothesis of reduced social motivation in ASD. In the current study we develop a novel task to test social reward preference using a tablet computer (iPad), where two differently coloured buttons were associated with a social and a nonsocial rewarding image respectively. 63 young children, aged 14–68 months, with and without a diagnosis of ASD took part in the study. The experimental sessions were also recorded on video, using an in-built webcam on the tablet as well as an external camera. Children with ASD were found to show a reduced relative preference for social rewards, indexed by a lower proportion of touches for the button associated with the social reward image. Greater social preference as measured using the tablet-based task was associated with increased use of social communicative behaviour such as eye contact with the experimenter and social smile in response to the social reward image. These results are consistent with earlier findings from eye-tracking studies, and provide novel empirical insights into atypical social reward responsivity in ASD

Reading comprehension in autism spectrum disorders: The role of oral language and social functioning

Reading comprehension is an area of difficulty for many individuals with autism spectrum disorders (ASD). According to the Simple View of Reading, word recognition and oral language are both important determinants of reading comprehension ability. We provide a novel test of this model in 100 adolescents with ASD of varying intellectual ability. Further, we explore whether reading comprehension is additionally influenced by individual differences in social behaviour and social cognition in ASD. Adolescents with ASD aged 14-16 years completed assessments indexing word recognition, oral language, reading comprehension, social behaviour and social cognition. Regression analyses show that both word recognition and oral language explain unique variance in reading comprehension. Further, measures of social behaviour and social cognition predict reading comprehension after controlling for the variance explained by word recognition and oral language. This indicates that word recognition, oral language and social impairments may constrain reading comprehension in ASD