Atypical Pattern of Frontal EEG Asymmetry to Direct Gaze in Young Children with Autism Spectrum Disorder

Background:

It has been suggested that another person’s direct gaze is not socially motivating for individuals with autism spectrum disorder (ASD) and therefore they ignore it. This assumption has gained psychophysiological support from previous findings indicating that, contrary to typically developing children, children with ASD did not show greater relative left-sided, approach-related frontal EEG activity to direct gaze in comparison to shut eyes. Relative right- and left-sided asymmetries in the frontal alpha-band EEG activity have been associated with activation of the avoidance- and approach-related motivational brain systems, respectively. The children in the previous study were, however, school-aged and high-functioning children with ASD, leaving it open whether a similar pattern of responses would be observed already at an earlier age, and whether the findings could be generalised to low-functioning ASD.

Objectives:

The aim of the study was to investigate motivation-related brain responses to direct gaze in young, low-functioning children with ASD. In order to ensure that the possible abnormal findings were autism-specific, we also investigated an IQ-matched comparison group of children without ASD in addition to a normative comparison group of age-matched typically developing children.

Methods:  

Twenty young (2.5-5.5 years of age) children with ASD, 20 typically developing children and 18 children with developmental delay without ASD participated in the study. The frontal alpha-band EEG (EGI Geodesic 128 channel system) activity was measured whilst the children viewed photos of faces with direct or downcast gaze and cars pictured from front or back view. On each trial, the stimulus was static for the first 2 seconds and then loomed towards the child for 3 seconds, creating an impression of an approaching person (or a car). Frontal EEG asymmetry was analysed separately to the static and moving phases of the stimuli.

Results:  

The results showed that the typically developing children showed greater approach-related frontal EEG activity to direct gaze compared to downcast gaze. In children with ASD, the downcast gaze elicited greater approach-related frontal EEG activity compared to the direct gaze. In the children with developmental delay without ASD, there was no significant difference between the gaze conditions in the frontal EEG activity. These patterns of activity were obtained for the moving but not static phases of the stimuli.

Conclusions:  

The pattern of frontal EEG activity to direct gaze was different in children with ASD compared to the other groups. The findings suggest that the lack of normative approach-related motivation towards another person´s direct gaze is evident early in the autistic development. It also strengthens the role of eye contact in abnormal social development of children with ASD. Interestingly, the dynamic stimuli seemed to be more sensitive than static stimuli to reveal differences in the motivation-related brain responses.