Visual event-related potentials to biological motion stimuli in autism spectrum disorders

Abstract

Atypical visual processing of biological motion contributes to social impairments in autism spectrum disorders (ASD). However, the exact temporal sequence of deficits of cortical biological motion processing in ASD has not been studied to date. We used 64-channel electroencephalography to study event-related potentials associated with human motion perception in 17 children and adolescents with ASD and 21 typical controls. A spatio-temporal source analysis was performed to assess the brain structures involved in these processes. We expected altered activity already during early stimulus processing and reduced activity during subsequent biological motion specific processes in ASD. In response to both, random and biological motion, the P100 amplitude was decreased suggesting unspecific deficits in visual processing, and the occipito-temporal N200 showed atypical lateralization in ASD suggesting altered hemispheric specialization. A slow positive deflection after 400 ms, reflecting top-down processes, and human motion-specific dipole activation differed slightly between groups, with reduced and more diffuse activation in the ASD-group. The latter could be an indicator of a disrupted neuronal network for biological motion processing in ADS. Furthermore, early visual processing (P100) seems to be correlated to biological motion-specific activation. This emphasizes the relevance of early sensory processing for higher order processing deficits in ASD.

Keywords: N200; P100; event-related-potentials; hemisphere-asymmetry; motion perception.

Fig. 1

Example of experimental stimuli and stimuli presentation.

Fig. 2

Topographic scalp maps in (A) typical controls and (B) autistic children (ASD) in both experimental conditions and the difference maps (walker–scramble).

Fig. 3

ERPs to both experimental conditions and in typical controls (solid line) and autistic children (ASD; dashed line) for (A) the P100 at electrodes O1 (left hemisphere) and O2 (right hemisphere), and (B) the N200 at electrodes P9 (left hemisphere) and P10 (right hemisphere).

Fig. 4

P400+ at electrodes CPz, Pz, PO1, PO2, P1 and P2 (averaged) walker condition and scramble condition for typical controls (dashed line) and ASD.

Fig. 5

(A) Difference waves at the surface electrodes Cz, P10 (right hemisphere) and P9 (left hemisphere) in typical controls (solid line) and ASD (dashed line). (B) Dipole localization. (C) Dipole waves, displaying activity in the left and right occipito-temporal junction.

Fig. 6

Correlation between P100 amplitude (averaged for both conditions and hemispheres) separately for each group and (A) N200 lateralisation (P10–P9, averaged for both conditions), (B) P400+ amplitude (averaged for both conditions), (C) dipole activity (averaged for both hemispheres). Typical controls are indicated by circles and subjects with ASD by stars.