Neurophysiological Markers of ASD in Tuberous Sclerosis Complex
Objectives: To identify potential neurophysiological markers of ASD in infants with TSC by assaying low- and high-level visual processing.
Methods: The data reported form part of an ongoing multi-site, longitudinal investigation mapping the development of infants with and without TSC from 6 months through to 36 months. High-density electroencephalographic (EEG) recordings were conducted with infants with TSC and age-matched typically developing controls. Low-level visual processing was assessed using a pattern-reversal visual evoked potential (VEP) paradigm. Higher-level visual processing was assessed using a face-object paradigm. Peak amplitude and latency of the P1 was quantified in the VEP paradigm and mean amplitude of the N290 and P400 was quantified in the face-object task. ASD was assessed at 24 and 36 months with the Autism Diagnostic Observation Schedule and developmental level was assessed using the Mullen Scales of Early Learning.
Results: Preliminary findings demonstrate that children with TSC and ASD show distinct patterns of neurophysiological responding across low-level and higher-level visual processing paradigms by 24 months. In terms of low-level processing, the P1 was of higher amplitude and longer latency in TSC and ASD children compared to typically developing children (Figure 1). In terms of higher-level visual processing, children with TSC and no-ASD and typically developing children showed differential N290 and P400 amplitudes to faces versus objects; however, there was a lack of differential responding in children with TSC and ASD (Figure 2).
Conclusions: Preliminary findings suggest that children with TSC who meet criteria for ASD display distinct electrophysiological responses to visual stimuli. Specifically, these findings point towards alterations in both low-level and higher-level visual processing in infants with TSC and ASD. Disturbances in the neural processing of visual stimuli may be a contributing pathway to the high rates of ASD in TSC.