Pivotal Response Treatment Increases Neural Processing Efficiency of Faces in Children with Autism Spectrum Disorder

Background:  

Pivotal Response Treatment (PRT) is an empirically validated, naturalistic behavioral intervention that uses the principles of Applied Behavior Analysis (ABA) to address core deficits in social communication in individuals with Autism Spectrum Disorder (ASD). Originally developed to promote language acquisition in nonverbal children with ASD (Koegel et al., 1987), PRT has been expanded to target other developmental areas. Recent work has demonstrated improvements in pragmatic language, social engagement, and adaptive functioning skills (Ventola et al., 2014), as well as normalization of neural activation (Ventola et al., 2015) following a 16-week course of PRT. Effects of PRT on the temporal dynamics of neural activation have yet to be studied. By utilizing the precise temporal resolution of electroencephalography (EEG), this study aims to assess changes in the efficiency of neural processing of social information following a 16-week course of PRT. 

Objectives:  

To identify changes in temporal dynamics of the neural processing of social information following a 16-week course of PRT.

Methods:  

Seven children with ASD between the ages of 4 and 6 years received PRT (6 hours with the child and 2 hours with the parent per week) for 16 consecutive weeks. Participants completed an EEG session, recorded with a 128-channel Hydrocel Geodesic sensor net, before and after treatment and at 16-week follow-up. A subset of participants (n = 3) completed an additional EEG 16 weeks prior to the start of treatment as a waitlist control group. During EEG recording, participants were presented with 73 computer-generated faces that displayed either neutral or fearful expressions. Event-related potentials (ERPs) were measured over the right occipitotemporal region. The latency and amplitude of ERP components that reflect early visual processing and face processing (P100 and N170, respectively) were examined at each time point. 

Results:  

An overall main effect of treatment on N170 latency was observed [F(1,6) = 11.34, p = .015], signifying a change in the efficiency of face processing. Post-hoc paired samples t-tests revealed that a significant reduction in N170 latency occurred to both neutral (p = .027) and fearful (p = .029) face stimuli following treatment. There were no significant changes in N170 amplitude or in either P100 latency or amplitude (ps > .05). Additionally, no significant change in N170 latency was observed over the 16-week period prior to treatment in the waitlist control group [F(1,2) = 2.45, p = .26]. Preliminary analyses of follow-up data suggest stability in increased efficiency of N170 latency.

Conclusions:  

These preliminary findings suggest that a 16-week course of PRT is associated with increased processing efficiency of socially salient stimuli. The improvements were seen only in brain responses associated with social perception (N170), as opposed to lower-level visual processes (P100), suggesting focal treatment effects on social processing. Waitlist control data indicate that this is unlikely to related to practice effects, and follow-up data suggest that these effects endure beyond treatment. Results suggest specific and persistent action of PRT on neural systems subserving social perception.