Autism is characterized by a variety of abnormalities such as impaired social abilities, repetitive behaviors, and cognitive impairments. One of the things that individuals with autism tend to struggle with is face processing. Researchers have identified the N290 as a region related to face processing in infants and the N170 region has been identified as a face processing region in children and adults. Atypical activity in the N170 region has been found in children and adults with autism, which has led researchers to question whether atypical activity in the N290 would be predictive of the development of autism.
Maggie Guy's "Cortical Source Analysis of the Face Analysis of the Face Sensitive N290 ERP Component in Infants at High Risk for Autism" studies the N290 region as a potential biomarker for autism. The study involved using electroencephalography (EEG) to record event-related potentials (ERPs) in infants with Fragile X syndrome and infants with older siblings diagnosed with autism. Event-related potentials are neural responses to specific stimuli. In this case, the stimuli consisted of familiar and unfamiliar faces and familiar and unfamiliar toys. They also took structural MRIs of the infants when possible to compare the brain structures of infants with an increased risk for autism to infants with a low risk for autism. In the study, infants with Fragile X syndrome had significantly greater activation of the N290 region than siblings of children with autism and typically developing infants. In the analysis of the MRI scans, infants with Fragile X syndrome had peak activation in the right middle fusiform gyrus that correlated with the increased activation of the N290 region. Regions of the brain that were identified as abnormal in all infants with an increased risk for autism were the middle occipital gyrus, right cuneus, right lingual gyrus, left inferior temporal gyrus, and middle frontal gyrus. These results suggest that monitoring the development of these regions in infants could help children to receive autism diagnoses even earlier than what is currently possible.
Elizabeth Shepard and colleagues conducted cross-sectional and longitudinal studies that look into face processing in children at high risk for autism. They periodically tested children's face processing abilities from the ages of 7 months to 7 years. Their paper, "Neural and behavioral indices of face processing in siblings of children with autism spectrum disorder (ASD): a longitudinal study from infancy to mid-childhood" details their use of a face processing task with EEG recordings as the measures of data collection in children. The task required to children to press buttons to indicate whether or not they had seen the image before. For infants, they conducted a passive viewing task using EEG and eye-tracking technology to gather data. The images shown were faces and common objects. Similar to Maggie Guy's study, children with Fragile X syndrome and sibling of children with autism were labelled as high risk. Results of the study of older children found that boys with an high risk for autism had lower accuracy when determining whether they had previously seen a face or body, whereas high and low risk girls performed similarly. Accuracy for cars and scenes and the reaction times were similar across both low and high risk children. EEG recordings found higher amplitudes in the N170 region in high risk children during face processing tasks. High-risk children with slower reaction times and higher amplitudes in the N170 exhibited the most severe social-communication impairments and more severe sensory symptoms. In the longitudinal study, high risk infants who exhibited the most typical N290 results during face processing had more severe social-communication impariments in mid-childhood. They attribute this to the N290's role in noise processing. When they separated the N290 data for face processing and noise processing, they found that these children had smaller N290 amplitudes for noise stimuli. This could suggest that infants at high risk for autism are preferentially directing their attention towards non-social stimuli. Overall, the N290 did not prove to be indicative of behavior in mid-childhood.
These studies, although they aren't conclusive, show the importance of studying face processing in infants and its effects on development. There are certainly differences in face processing in infants at high risk for autism and continuing research on this subject could bring researchers to understand why. Studying face processing could not only lead to earlier diagnoses, but also a better understanding of autism and its progression.
Sources:
Guy, M.W., Richards, J.E., Roberts, J.E. Cortical Source Analysis of the Face Sensitive N290 ERP Component in Infants at High Risk for Autism. Brain Sci. 2022, 12, 1129. https://doi.org/10.3390/brainsci12091129
Shepard, E., Milosavlijevic, B., Mason, L., Elsabbagh, M., Tye, C., Gliga, T., Jones, E.J., Charman, T., Johnson, M. (2020). Neural and behavioral indices of face processing in siblings of children with autism spectrum disorder (ASD): a longitudinal study from infancy to mid-childhood. Cortex. 127, 162-179. https://doi.org/10.1016/j.cortex.2020.02.008
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