Neural Correlates of Response to Joint Attention in Toddlers with Autism Spectrum Disorder and Their Typically Developing Peers.

Background:

Joint attention development is atypical in children with autism spectrum disorder (ASD). As far as initiation of joint attention is concerned, the literature points unanimously to an impaired development in individuals with ASD, whereas there is less agreement concerning response to joint attention, as observational methods alone do not consistently detect differences between children with ASD and typically developing (TD) children. On the other hand, toddler studies using eye-tracking, as well as neuroimaging research in older children suggest that, in spite of a preserved gaze-following ability, response to joint attention in ASD and TD children might be qualitatively different.

Objectives:

With this study we have been investigating the neural correlates of joint attention response in toddlers with ASD and their TD peers using fNIRS, to gain a deeper insight into joint attention development in ASD.

Methods:

We are planning to test 20 toddlers with ASD and 20 TD toddlers. 40% of total data has been collected to date, as we have tested 5 toddlers with ASD (all boys, mean age 3.13 ± 0.63) and 13 TD controls (6 boys, mean age 2.99 ± 0.68). Participants watched fragments of age-appropriate cartoons (duration: 11-13 s) interspliced by a static baseline (duration: 13-15 s). In 50% of trials, the start of the cartoon is signalled by the experimenter (joint attention condition). In the other 50% of trials, the attentional cue is a computer sound and the experimenter looks away from the screen while the cartoon plays.

Results:

Preliminary results (ASD: 25% of data analysed, TD: 65% of data analysed) show group differences over the effects of joint attention over dorsomedial prefrontal cortex (DMPFC) and right temporo-parietal junction (rTPJ). Over DMPFC we found an ATTENTION x GROUP interaction in the 0-5 s time-window (F(1,16) = 11.719, p =.002). Follow-up analysis shows that effects of joint attention were only present in the TD group (F(1,12) = 16.265, p = .001). Over rTPJ, the ATTENTION x GROUP interaction approaches significance in the 10-15 s time-window (inferior rTPJ/Brodmann area 41: F (1, 14) = 4.348, p =.059; superior rTPJ/Brodmann area 40: F (1, 13) = 4.163, p =.061). Follow-up shows that the interaction is due to a lack of activation during joint attention in the ASD group (p >.05).

Conclusions:

We found atypical activation in children with ASD during response to joint attention in areas (DMPFC and rTPJ) that are involved both in general attentional orienting and in mentalisation. The timing of the activation over these areas suggests that children with ASD do orient to social attention cues, but this process is slower for them than for their TD peers, which in turn may impair their ability to infer the social intention of the initiator of joint attention.