Social Perception Deficits In Children with ASD : Correlations with STS Anatomical Connectivity

Background: Social perception deficits in ASD have recently been quantified with eye-tacking methodology. Results have shown that children with ASD have a reduced preference for viewing social stimuli and spend a smaller percentage of time examining the core features of the face (Saitovitch et al., IMFAR 2011). In addition, anatomo-functional abnormalities in the social brain (superior temporal sulcus, orbito-frontal cortex, amygdala and fusiform gyrus) have been previously described in ASD. More recently, diffusion neuroimaging techniques have also suggested that ASD is associated with white matter abnormalities, suggesting anatomical connectivity disruptions in this disorder.

Objectives: To correlate social perception eye-tracking data in children with ASD with diffusion tensor imaging MRI data.

Methods: ASD diagnosis was based on DSM IV-R and ADI-R criteria. Participants were 9 ASD boys (mean age : 12,3 ± 3,7 years; mean IQ : 69,2 ± 32,4). Eye-tracking studies (Tobii T120 Eye Tracker) were performed during presentation of social relevant video clips (film and cartoon versions), non-social control video clip and during presentation of static pictures, taken from each video clip. Gaze parameters were measured in areas with strong social contents (eyes, mouth, and face) and in non-social areas. White matter integrity was voxel-wise assessed over the whole brain using high-angular resolution diffusion tensor imaging (DTI). High angular resolution diffusion images (HARDI) were acquired on a GE-Signa 1.5 T using an echoplanar sequence (41 directions, TE=70 ms; TR=9000 ms; 2*1.8*1.8 mm3; b=1500 s/mm2). Fractional anisotropy (FA) maps were estimated with Brainvisa software (http://brainvisa.info) and then non linearly spatially normalized on study-specific FA template and spatially smoothed (8mm) using SPM5 software (http://www.fil.ion.ucl.ac.uk/spm/). Correlation analysis between FA and eye-tracking data were performed with SPM5.

Results:  Significant correlations were observed between gaze parameters and FA values: the less children with ASD looked to social content areas in the scene (eyes, mouth, face), the more FA values were reduced in “social brain” areas (posterior and anterior arcuate fasciculi). In addition, the longer children with ASD looked at non-social features of the scene, the more FA values were reduced in same “social brain” areas.

Conclusions: The present results obtained through direct comparison between imaging data and gaze parameters show a correlation between structural abnormalities and behavioural patterns. These preliminary results suggest that social perception deficits in ASD children are related with abnormal anatomical connectivity in regions of the social brain.