Electrophysiological Analysis of Empathy and Theory of Mind Function in Children with Autism Spectrum Disorder

Background:  Previous research has identified the mirror neuron system (MNS) as a collection of neurons involved in the integration of observation and execution into a matching system. MNS activity monitored by EEG has been indexed through power suppression from 8-13Hz (mu rhythms) over the sensorimotor cortex.

Objectives: Typically developing (TD) individuals show mu power suppression during goal oriented actions in observation and execution. Individuals with autism spectrum disorder (ASD) show suppression only in goal oriented actions involving execution and not observation.

Methods: Our research focused upon two methods for analyzing social cognition through observation of visual stimuli, empathy and theory of mind (ToM).

Results: The ToM method revealed results that reinforced a previous study that dissociates ToM into two subcomponents. The empathy study applied to TD children revealed mu power suppression to emotional faces. In contrast, children with ASD showed similar mu power across different conditions. This result suggests that children with ASD do not engage the mirror neuron system in face emotion processing as do TD children. In addition, TD children show higher mu power suppression in the right hemisphere than in the left. However, children with ASD showed no mu power difference between hemispheres.

Conclusions: Therefore, the electrophysiological data collected through these two methods contribute to the theory that children with ASD are deficient in their ability to suppress mu rhythms. These results provide a fundamental basis for an ongoing study that is investigating whether the electrophysiological discrepancies in ASD are functional, structural or both.