Rethinking Etiology: Autism Spectrum Disorder

In research conducted by Dr. Maggie Guy and colleagues, the study titled Neural correlates of face processing in etiologically-distinct 12-month-old infants at high-risk of autism spectrum disorder, reports the EEG recordings of infants at high risk of developing Autism Spectrum Disorder (ASD). Data were collected among three groups; infants with siblings diagnosed with ASD (ASIBs), infants with fragile X syndrome (FXS), and a low-risk control group. Their particular focus was on areas of activity associated with face processing, with the primary ERP components being N290 and P400 located in the temporal and occipital regions. Dr. Guy and colleagues averaged the activity levels of the event-related potentials (ERP) across each of the trials. They found that ASIBs showed muted N290 responses, while infants with FXS had higher amplitude responses. Their results suggest that different neural activity patterns in high-risk infants distinguish the two ASD groups and reveal different developmental trajectories.

While very compelling, Dr. Guy’s research brings with it additional questions regarding the neural differences between different high-risk ASD groups. If there are apparent differences in neural activity between ASIBs and individuals with FXS, does the same apply to where precisely in the brain that activity takes place? In a study conducted by Andrew Mckechanie and colleagues, this question is delved into more detail using a functional neuroimaging approach. Like Dr. Guy’s study, the area of interest concerns facial processing and specialization.

Using functional magnetic resonance imaging (fMRI), Mckechanie’s study manages to explore further the differences in brain activation between individuals with idiopathic autism, FXS with no autism diagnosis, and individuals with FXS with a comorbid autism diagnosis. The study recorded the blood-oxygen-level-dependent (BOLD) signals for both groups in response to images of fearful and neutral faces. According to the data produced, they found that there was significantly reduced activation in the left superior temporal gyrus and superior temporal sulcus in individuals with FXS and comorbid autism compared to the participants with FXS alone. Their data suggest that autism in FXS and idiopathic ASD have significant differences compared to those of non-autistic individuals with FXS. With the addition of Dr. Guy’s research, the combination of both studies may suggest altogether that there are further groups that might be included in future research. Autism spectrum disorder does encompass a wide variety of symptoms, but as the research suggests, it overall might have the same neurological basis with regards to facial processing mechanisms.

References


McKechanie, A. G., Campbell, S., Eley, S., & Stanfield, A. C. (2019). Autism in Fragile X Syndrome; A Functional MRI Study of Facial Emotion-Processing. Genes, 10(12), 1052. https://doi.org/10.3390/genes10121052



Guy, M. W., Richards, J. E., Tonnsen, B. L., & Roberts, J. E. (2018). Neural
correlates of face processing in etiologically-distinct 12-month-old infants at high-risk of autism spectrum disorder. Developmental cognitive neuroscience, 29, 61-71. https://doi.org/10.1016/j.dcn.2017.03.002