"Despite the fact that the siblings of those with autism did not have a diagnosis of autism or Asperger syndrome, they had decreased activity in various areas of the brain (including those associated with empathy, understanding others’ emotions and processing information from faces) compared to those with no family history of autism. The scans of those with autism revealed that the same areas of the brain as their siblings were also underactive, but to a greater degree. (These brain regions included the temporal poles, the superior temporal sulcus, the superior frontal gyrus, the dorsomedial prefrontal cortex and the fusiform face area.)"
From the article:
"…atypical neural response within these brain areas in autism and sibling groups specifically to happy faces may reflect the possibility that an implicit response to happy faces is driven by empathy—impairments of which have a central role within the phenotype of autism—whereas the response to fearful stimuli (found in this study to be intact in siblings but not individuals with autism) is likely driven by their role as indicators of threat.”
M D Spencer, R J Holt, L R Chura, J Suckling, A J Calder, E T Bullmore, S Baron-Cohen. A novel functional brain imaging endophenotype of autism: the neural response to facial expression of emotion. Translational Psychiatry, 2011; 1 (7): e16 DOI: 10.1038/tp.2011.18
The genesis of autism is shaping up to be strikingly similar to that of the endophenotypic development of schizophrenia. I can only imagine that scientists will start investigating genetic markers as well to see if there are a series of genes that contribute to the decreased activation in these cortical areas. Several of the areas they reference have been previously implicated in other neurological conditions involving distorted or abnormal facial perception, such as prosopagnosia.
The only disagreeable notion that this article puts forth is the notion of a definitive set of biomarkers, hence why I changed the title to reflect what I feel is the article’s true gist, sans academic grandstanding.