Change of Neurophysiological Correlates of Biological Motion Processing By the Group Based SOSTA-FRA Intervention in High Functioning Children and Adolescents with ASD
Group based psychotherapy focusing on improvement of social and self-regulation skills is the intervention of choice in high functioning children and adolescents with autism spectrum disorder (ASD). Systematic empirical evaluation of such interventions aims at elucidating mechanisms by which they improve social skills in ASD. Neurophysiological studies can contribute by assessing neural correlates of behavioral change. Biological motion processing is a fundamental skill required for almost all social interactions, as we need to interpret dynamic social signals such as gestures, body language or facial expressions. Biological motion processing therefore seems well suited for evaluating perceptual and cognitive changes following social skills trainings in ASD.
We hypothesized that the group based SOSTA-FRA intervention would change neural correlates of visual and cognitive biological motion processing in individuals with ASD.
Data was collected within a randomized controlled trial. The intervention group received twelve sessions of the manualized SOSTA-FRA training, while the control group continued to receive treatment as usual (TAU). Both groups were assessed three times (t1=baseline, t2=post intervention, t3=3-months follow-up), completing both questionnaires and the neurophysiological assessment at all time points. In each group 17 matched children participated in the neurophysiological assessment at all three time-points and provided sufficient artifact free data for analysis. The task comprised two conditions in which pointlight-displays of biological (walking human figure) and non-biological motion (scrambled stimulus derived from the human stimulus) were shown and participants were instructed to discriminate between the two motion types. Taking into account hemisphere and condition we compared amplitudes and latencies of the P100, N200 and P400 event related potentials (ERPs) between the two groups across all three measurements.
Both groups showed a constant high performance on the motion discrimination task and no changes across time (F2,60=.273;p=.762) or between groups (group*time: F2,60=.791; p=.458) were evident. Still, ERP analysis revealed reduced N200 latencies at three months follow-up for the SOSTA-FRA but not the TAU group (F2,64= 4.067; p=.022).
While no improvement in task performance could be observed, likely due to ceiling effects, ERP results point towards change of neural function following the intervention. The intervention led to faster early neural processing of complex visual stimuli, which has been discussed as a deficit typical for ASD. While the exact mechanisms that lead to this change need to be investigated in further detail, results indicate improved visual processing strategies by SOSTA-FRA.