Association of autism tendency and hemodynamic changes in the prefrontal cortex during facial expression stimuli measured by multi-channel near-infrared spectroscopy.

AIM: The aim of this study is to examine the hemodynamic changes induced by the cognitive process of facial expression by using multi-channel near-infrared spectroscopy in healthy subjects with varying degrees of autism tendency.
METHODS: Subjects were 38 volunteers, 20 men and 18 women. Autism tendency was measured by the Autism Spectrum Quotient. The hemodynamic changes in the prefrontal cortex were measured by 24-channel near-infrared spectroscopy system, while subjects were asked to judge their own emotional response to standardized pictures of eight kinds of facial expressions on a computer screen.
RESULTS: There were significant negative correlations between Autism Spectrum Quotient scores and accuracy of fearful expression recognition as well as increases in the concentration of oxygenated hemoglobin in response to four kinds of emotional faces (fear, contempt, sadness and disgust).
CONCLUSION: Our findings suggest that the greater tendency to autism that subjects have, the more difficulty they have in recognizing a fearful expression and the less hemodynamic change in the prefrontal cortex they show in response to negative facial expressions.