Basic abnormalities in visual processing affect face processing at an early age in autism spectrum disorder.
BACKGROUND
A detailed visual processing style has been noted in autism spectrum disorder (ASD); this contributes to problems in face processing and has been directly related to abnormal processing of spatial frequencies (SFs). Little is known about the early development of face processing in ASD and the relation with abnormal SF processing. We investigated whether young ASD children show abnormalities in low spatial frequency (LSF, global) and high spatial frequency (HSF, detailed) processing and explored whether these are crucially involved in the early development of face processing.


METHODS
Three- to 4-year-old children with ASD (n = 22) were compared with developmentally delayed children without ASD (n = 17). Spatial frequency processing was studied by recording visual evoked potentials from visual brain areas while children passively viewed gratings (HSF/LSF). In addition, children watched face stimuli with different expressions, filtered to include only HSF or LSF.


RESULTS
Enhanced activity in visual brain areas was found in response to HSF versus LSF information in children with ASD, in contrast to control subjects. Furthermore, facial-expression processing was also primarily driven by detail in ASD.


CONCLUSIONS
Enhanced visual processing of detailed (HSF) information is present early in ASD and occurs for neutral (gratings), as well as for socially relevant stimuli (facial expressions). These data indicate that there is a general abnormality in visual SF processing in early ASD and are in agreement with suggestions that a fast LSF subcortical face processing route might be affected in ASD. This could suggest that abnormal visual processing is causative in the development of social problems in ASD.
Vlamings
Petra Hendrika Johanna Maria
PH
Department of Cognitive Neuroscience, Universiteit Maastricht, The Netherlands. Vlamings@psychology.unimaas.nl
Jonkman
Lisa Marthe
LM
van Daalen
Emma
E
van der Gaag
Rutger Jan
RJ
Kemner
Chantal
C
D001921:Brain / Q000503:physiopathology*; D002659:Child Development Disorders, Pervasive / Q000503:physiopathology*; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000503:physiopathology; D005074:Evoked Potentials, Visual / Q000502:physiology; D005149:Facial Expression; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*