Highlights

Abstract

Keywords

Introduction

Experimental Procedures

Subjects

Data collection

Data processing

Activity Statistical analysis

Connectivity Statistical analysis

Results

Behavior assessments upon enrollment

Activity comparisons

Information flow Comparisons

Correlation of connectivity with ABC, CARS, and PEP-3

Discussion

Intensity of regional activity

Intensity of information flow

Correlation between information flow and CARS score

Limitations

Uncited references

References

Abstract

Resting gamma-band brain networks are known as an inhibitory component in functional brain networks. Although autism spectrum disorder (ASD) is considered as with imbalanced brain networks, the inhibitory component remains not fully explored. The study reported 10 children with ASD and 10 typically-developing (TD) controls. The power spectral density analysis of the gamma-band signal in the cerebral cortex was performed at the source level. The normalized phase transfer entropy values (nPTEs) were calculated to construct brain connectivity. Gamma-band activity of the ASD group was lower than the TD children. The significantly inhibited brain regions were mainly distributed in the bilateral frontal and temporal lobes. Connectivity analysis showed alterations in the connections from key nodes of the social brain network. The behavior assessments in the ASD group revealed a significantly positive correlation between the total score of Childhood Autism Rating Scale and the regional nPTEs of the right transverse temporal gyrus. Our results provide strong evidence that the gamma-band brain networks of ASD children have a lower level of brain activities and different distribution of information flows. Clinical meanings of such imbalances of both activity and connectivity were also worthy of further explorations.

Introduction

Autism spectrum disorder (ASD) is a developmental neural disorder defined by abnormal social behavior and deficits in communication, repetitive behaviors, and restricted interests (Mostafavi and Gaitanis, 2020, Berenguer et al., 2020, American Psychiatric Association, 2013). There is a trending up the incidence of ASD among Asian kids despite about 0.36% nowadays (Qiu et al., 2020). ASD has become a non-negligible risk factor affecting the physical and mental health of children and adults. Although vast numbers of studies have been investigated, the etiology and pathogenesis of ASD remain unclear.

Most electroencephalogram (EEG) studies suggest that there are abnormalities in children with ASD, especially in the gamma-band (Rojas & Wilson, 2014). Brain activity in the gamma-band is associated with the function of gamma-aminobutyric acid (GABA) neurons, that is, it represents the inhibitory neurotransmitter system (McNally & McCarley, 2016). The current explanation of the pathogenesis of ASD is predominantly based on the excitation-inhibition imbalance theory of signal processing in the brain (Sohal & Rubenstein, 2019). In terms of the activity level of the brain regions, van Diessen et al. reported a significant increase at the activity level of resting gamma-band among children with ASD (van Diessen et al., 2015). Meanwhile, Cornew et al. also found the same phenomena at the anterior temporal lobe, posterior frontal lobe, and occipital lobe (Cornew et al., 2012). In contrast, Sheikhani et al. reported a significant reduction in bilateral frontal gamma-band activity (Sheikhani et al., 2009, 2012). Considering the inter-regional connectivity, Shou et al. and Ye et al. observed excessive connectivity in the bilateral frontal lobe, left parietal lobe, left temporal lobe, and subcutaneous region in the resting state gamma-band (Shou et al., 2018, Ye et al., 2014). Lajiness-O’Neill et al. found reduced connections in the frontal and parietal gamma-band (Lajiness-O’Neill et al., 2018). Thus, researchers still have not achieved consensus regarding brain activity and connectivity in the gamma-band.