Functional connectivity networks in the autistic and healthy brain assessed using Granger causality

Pollonini, Luca; Patidar, Udit; Situ, Ning; Rezaie, Roozbeh; Papanicolaou, Andrew C.; Zouridakis, George

doi:10.1109/iembs.2010.5626702

Cited by 50 publications

(64 citation statements)

References 34 publications

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“…In an EEG study comparing children with autism to healthy controls, children with autism showed a loss of small-world architecture, characterized by a significantly increased path length and reduced clustering [313,314]. Similar findings were also demonstrated for high-functioning adults with autism and for those with Asperger syndrome [315,316]. Another neurodevelopmental disorder that has been studied using a network approach is ADHD.…”

Section: Resultsmentioning

confidence: 87%

Sensory and motor secondary symptoms as indicators of brain vulnerability

Levit‐Binnun

Davidovitch

Golland

2013

J Neurodevelop Disord

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In addition to the primary symptoms that distinguish one disorder from the next, clinicians have identified, yet largely overlooked, another set of symptoms that appear across many disorders, termed secondary symptoms. In the emerging era of systems neuroscience, which highlights that many disorders share common deficits in global network features, the nonspecific nature of secondary symptoms should attract attention. Herein we provide a scholarly review of the literature on a subset of secondary symptoms––sensory and motor. We demonstrate that their pattern of appearance––across a wide range of psychopathologies, much before the full-blown disorder appears, and in healthy individuals who display a variety of negative symptoms––resembles the pattern of appearance of network abnormalities. We propose that sensory and motor secondary symptoms can be important indicators of underlying network aberrations and thus of vulnerable brain states putting individuals at risk for psychopathology following extreme circumstances.

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Section: Resultsmentioning

confidence: 87%

Sensory and motor secondary symptoms as indicators of brain vulnerability

Levit‐Binnun

Davidovitch

Golland

2013

J Neurodevelop Disord

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“…EEG and MEG connectivity studies using graph analysis generally report autism to be associated with sub-optimal network properties, such as less clustering, larger characteristic path, reduced eigenvector centrality (a measure of the importance of nodes as communication hubs), and an architecture less typical of small-world networks [89–91,114,133,135,136]. Small-world networks are thought to be striking an optimal balance between integration and segregation, making them particularly efficient.…”

Section: Resultsmentioning

confidence: 99%

“…The use of functional connectivity features for diagnostic application is also relevant since high accuracy (85–95%) has been reported by many independent research teams [88,97,102,125,126,135]. However, how such biomarkers would perform in infants for an early diagnosis is still an open question and fraught with several pragmatic and ethical complications [185].…”

Section: Discussionmentioning

confidence: 99%

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

2017

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BackgroundAlthough 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.Objectives1) 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).MethodsLiterature 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.ResultsOur 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.ConclusionsThe 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.

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“…One electroencephalography (EEG) based study found reduced functional connectivity in ASD during the resting state in the α band [23]. A series of studies of ASD using magnetoencephalography (MEG) found increased short-range and reduced long-range functional connectivity in the δ band [24], broadband abnormalities [25, 26, 27], decreased coherence in lower frequency bands [28], and abnormalities limited again just to the α band [26]. However, all of these studies lacked spatial specificity.…”

Section: Introductionmentioning

confidence: 99%

Altered Development and Multifaceted Band-Specific Abnormalities of Resting State Networks in Autism

Kitzbichler

Khan

Ganesan

et al. 2015

Biological Psychiatry

101

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Background Extensive evidence indicates that cortical connectivity patterns are abnormal in autism spectrum disorders (ASD), showing both over- and under-connectivity. Since, however, studies to date focused on either spatial or spectral dimensions, but not both simultaneously, much remains unknown about the nature of these abnormalities. In particular, it remains unknown whether abnormal connectivity patterns in ASD are driven by specific frequency bands, by spatial network properties, or by some combination of these factors. Methods Magnetoencephalography (MEG) recordings (15 ASD, 15 controls) mapped back onto cortical space were used to study resting state networks in ASD with both spatial and spectral specificity. The data were quantified using graph theoretic metrics. Results The two major factors that drove the nature of connectivity abnormalities in ASD were the mediating frequency band and whether the network included frontal nodes. These factors determined whether clustering and integration were increased or decreased in cortical resting state networks in ASD. These measures also correlated with abnormalities in the developmental trajectory of resting state networks in ASD. Lastly, these measures correlated with ASD severity in some frequency bands and spatially specific sub-networks. Conclusions Our findings suggest that network abnormalities in ASD are widespread, are more likely in subnetworks that include the frontal lobe, and can be opposite in nature depending on the frequency band. These findings thus elucidate seemingly contradictory prior findings of both over- and under- connectivity in ASD.

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Functional connectivity networks in the autistic and healthy brain assessed using Granger causality

Cited by 50 publications

References 34 publications

Sensory and motor secondary symptoms as indicators of brain vulnerability

Sensory and motor secondary symptoms as indicators of brain vulnerability

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

Altered Development and Multifaceted Band-Specific Abnormalities of Resting State Networks in Autism

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