Interhemispheric alpha-band hypoconnectivity in children with autism spectrum disorder

Abstract

Diverse genetic and environmental etiologies converge onto circuit level brain dysfunction in autism spectrum disorder (ASD), manifesting at a macroscopic level as aberrant neural connectivity. Previous studies have described atypical patterns of decreased short range and increased long range connectivity in ASD [1]. However, it remains unclear whether group level features of circuit dysfunction are consistently present across the range of cognitive function seen in the autism spectrum.

The dynamics of neural oscillations in the alpha range (6-12 Hz) are exquisitely sensitive to healthy development of functional and structural connectivity. Alpha-band coherence, measured with high temporal-precision electroencephalography (EEG) therefore represents an ideal tool for studying neural connectivity in developmental populations.

Here we examined spontaneous alpha phase coherence in a heterogeneous sample of 59 children with ASD and 39 age matched typically developing children. Using a data driven approach, we conducted an unbiased examination of all possible atypical connectivity patterns across all cortical regions.

Long-range hypoconnectivity was present in children with ASD compared to typically developing children, with temporal interhemispheric connectivity showing the largest difference between the two groups. Decreased long range alpha coherence distinguishes a heterogeneous group of ASD children from typically developing children. Interhemispheric temporal hypoconnectivity represents a fundamental functional difference in children with ASD across a wide cognitive and age range that may reflect white matter disturbances or increased signal variability at temporal sites in ASD.

Keywords: Alpha; Autism; Circuit dysfunction; Development; Electroencephalography; Neural connectivity.

Figure 1

Coherence matrices for the A) ASD group and B) TD group, demonstrating increased phase coherence in the TD group for many electrode pairs.

Figure 2

Group average resting state functional connections revealed by alpha phase coherence for A) ASD and B) typically developing groups. Connection color depicts value of connection strength, with all connections >0.4 phase coherence illustrated. C) Group differences in alpha phase coherence. Connection color indicates FDR correction value. All depicted connections represent decreased phase coherence in the ASD group. Labelled connection represents significant electrode pair group difference after implementing FDR correction at 0.05.

Figure 3

Dot plot demonstrating alpha phase coherence for electrode pair T9-T10 (with group mean and error bars representing SD) for both ASD and TD groups.