Poster B128, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Electrophysiological Correlates of an Excitatory:Inhibitory Imbalance in Children with Autism Spectrum Disorder
Lauren C. Shuffrey1,2,3,4, Lisa Levinson1, Heather L. Green1, Dayna Moya Sepulveda1, Grace Pak1, Alexis Becerra1, Karen Froud1; 1Teachers College, Columbia University, 2Columbia University Medical Center, 3New York State Psychiatric Institute, 4Center for Autism and the Developing Brain
Emergent evidence suggests that sensory processing abnormalities in Autism Spectrum Disorder (ASD) may be due to a neurochemical imbalance between excitatory glutamate (Glu) and inhibitory γ-aminobutyric acid (GABA) neurotransmission, also known as the excitatory:inhibitory (E:I) theory of ASD. Behavioral studies have demonstrated that healthy adults have a directional impairment of discrimination in conditions of large/high-contrast visual stimuli, thought to reflect surround suppression of motion selective neurons and to be driven by GABA (Tadin et al. 2003; Aaen-Stockdale et al. 2009). To explore possible consequences of imbalanced GABA:Glu neurotransmission on the visual system, we investigated surround suppression in ASD using a visual motion processing task during electroencephalography recording to derive the N1 event related potential (ERP). Five high-functioning medication-free children with ASD based on DSM-5 criteria and four typically developing (TD) children aged 7 – 12 years were recruited. Stimuli consisted of 1 cycle/degree vertical sine wave gratings surrounded by two-dimensional Gaussian envelopes drifting either right or left at a consistent speed. Stimulus size was either 5.0° or 0.7° and stimulus contrast was either 92% or 2.8%. In the high-contrast experiment, children with ASD showed significantly enhanced processing of large stimuli compared to small stimuli, thought to reflect weakened surround suppression (p=.007) as indexed by N1 ERP latency. Children with ASD had significantly shorter N1 ERP latencies to large/high contrast-stimuli than TD children (p=.006). This paradigm may have potential for use as a clinical outcome measure in research trials to evaluate the effectiveness of investigational pharmaceuticals that act on GABAergic neurotransmission.
Topic Area: PERCEPTION & ACTION: Vision