Academic journal article Iranian Journal of Psychiatry

Comparison between Face and Object Processing in Youths with Autism Spectrum Disorder: An Event Related Potentials Study

Academic journal article Iranian Journal of Psychiatry

Comparison between Face and Object Processing in Youths with Autism Spectrum Disorder: An Event Related Potentials Study

Article excerpt

Objective: Incapability in face perception and recognition is one of the main issues in autism spectrum disorders (ASD). Event related potential (ERP) studies have revealed controversial insights on autistic brain responses to faces and objects. The current investigation examined the ERP components of young children with ASD compared to a typically developing (TD) group when looking at the upright and inverted images of faces and cars .

Methods: Fourteen children and adolescents aged between 9 and 17 diagnosed as having ASD were compared with 18 age- gender matched normally developing individuals. All participants' ERPs were recorded while they were seeing the images of human faces and objects in both upright and inverted positions. The ERP components including N170 (latency and amplitude) were compared between the two groups in two conditions of upright and inverted using the repeated measure analysis method.

Results: The processing speed for upright faces was faster than the inverted faces in the TD group; however, the difference was not significant. A significant difference was observed in terms of N170 latency between the two groups for different stimulus categories such as objects and faces(p<0.05).Moreover, inverted vs. upright stimuli in both groups elicited a greater response in terms of N170 amplitude in both groups, and this effect was significantly prominent in the right hemisphere (p<0.05). The N170 amplitude turned out to be greater for the inverted vs. upright stimuli irrespective of the stimuli type and group .

Conclusion: These data suggest youths with ASD have difficulty processing information, particularly in face perception regardless of the stimuli orientation.

Key words: Autism, face, N170, object, event related potentials

Iran J Psychiatry 2013; 8:4:179-187

Autism is a developmental disorder characterized by communication and social interaction impairments (1). The ability to perceive and recognize faces is an important aspect of social cognition. A large body of research has provided compelling evidence for impairment in perception and recognition of faces in individuals with Autism Spectrum Disorders (2, 3, 4,5,6,7, and 8). Functional magnetic resonance imaging (fMRI) studies have reported that the right fusiform gyms shows a pronounced activation when typically developing (TD) individuals look at faces. Conversely, when individuals with autism spectrum disorder (ASD) confront facial cues, the activation of the fusiform face area is modest (9, 10). Event-Related Potentials (ERPs) have provided temporal information on face processing. In adults, the N170 (a negative component seen 170 ms following the stimulus onsetjhas been reported as a typical 'face' sensitive ERP component. Moreover, some studies have substantiated a lower amplitude and greater latency in N170 component captured in response to objects and words compared to that of faces. This non-face stimuli ERP pattem is predominantly seen in the right hemisphere rather than the left. Furthermore, inverted faces are found to induce N170 components of greater amplitude and shorter latency compared to the upright faces(ll, 12, 13).On the other hand, literatme lias argued that while N170 may not specifically belong to the face as a category, it might be a widely experienced phenomenon in people when recognizing faces (14- 18). Having noted the inconsistency in ERP studies with regards to ASD and face processing, it lias generally been reported that ASD individuals are worse in face processing compared to normal people (19, 20). Nevertheless, some behavioral studies have shown no difference between autistic individuals and normal adults with regards to response to the inverted faces (21, 22). However, some investigators have reported the lack of inversion effect in autistic individuals (23). In line with these data, some ERP studies have revealed that the N170 amplitude and latency remain unchanged when ASD individuals look at the inverted vs. …

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