19848
Perception of Biological Motion and Integration of Audio-Visual Stimuli in Infants at Risk for Autism
Objectives: Neural responses to BM and AVS were compared in infants at high-risk (HR; having an older sibling with ASD) and infants at normal risk (NR; no family history of ASD) for ASD. Through investigation of electrophysiological markers of BM and AVS, we aimed to (a) compare sensitivity to BM, (b) evaluate the degree of neural facilitation when processing multisensory stimuli, and (c) track the emergence of BM sensitivity and AVS facilitation to define typical vs. atypical trajectories.
Methods: Through a longitudinal design, HR (n=36), and NR (n= 42) infants were assessed at three-month intervals between three and twenty-four months. EEG was recorded with a 128-channel Hydrocel Geodesic Sensor net while infants viewed point-light displays illustrating BM and scrambled motion (SM; Experiment 1) or unimodal/bimodal auditory (tone) and visual (blue circle) stimuli (Experiment 2). In Experiment 1, two event-related potentials (ERPs) indexing BM perception (N200, negative deflection over right occipitotemporal scalp between 200-300ms; PSW, late anterior positive slow wave between 900-1500ms) were examined. In Experiment 2, two ERPs indexing multisensory integration (N100, negative deflection over fronto-central scalp between 90-145ms; N200, negative deflection over occipitotemporal scalp between 150-200ms) were assessed.
Results: Preliminary analyses from Experiment 1 found that neither HR nor NR infants exhibited significant differentiation between BM and SM (p>.05) at the six and nine-month time points. Descriptively, both groups exhibited attenuated N200 to BM, relative to SM, at six months, but this differentiation did not reach significance. NR infants, but not HR infants, continued to demonstrate this N200 attenuation to BM at nine months. In Experiment 2, 9 to 12 month NR infants exhibited a significantly enhanced N200 in response to AVS, (p=.01), whereas HR infants did not.
Conclusions: HR and NR infants elicited differential neural responses to BM at six months of age, and 9-12 month old HR infants exhibited neural atypicalities for AVS. These characteristic changes in neural response to BM and AVS over the first two years of life have the potential to serve as early indicators of ASD and to guide development of individually-tailored early interventions.