title: Autistic traits and brain activation during face-to-face conversations in typically developed adults.
abstract: BACKGROUND
  Autism spectrum disorders (ASD) are characterized by impaired social interaction and communication, restricted interests, and repetitive behaviours. The severity of these characteristics is posited to lie on a continuum that extends into the general population. Brain substrates underlying ASD have been investigated through functional neuroimaging studies using functional magnetic resonance imaging (fMRI). However, fMRI has methodological constraints for studying brain mechanisms during social interactions (for example, noise, lying on a gantry during the procedure, etc.). In this study, we investigated whether variations in autism spectrum traits are associated with changes in patterns of brain activation in typically developed adults. We used near-infrared spectroscopy (NIRS), a recently developed functional neuroimaging technique that uses near-infrared light, to monitor brain activation in a natural setting that is suitable for studying brain functions during social interactions.
  
  
  METHODS
  We monitored regional cerebral blood volume changes using a 52-channel NIRS apparatus over the prefrontal cortex (PFC) and superior temporal sulcus (STS), 2 areas implicated in social cognition and the pathology of ASD, in 28 typically developed participants (14 male and 14 female) during face-to-face conversations. This task was designed to resemble a realistic social situation. We examined the correlations of these changes with autistic traits assessed using the Autism-Spectrum Quotient (AQ).
  
  
  RESULTS
  Both the PFC and STS were significantly activated during face-to-face conversations. AQ scores were negatively correlated with regional cerebral blood volume increases in the left STS during face-to-face conversations, especially in males.
  
  
  CONCLUSIONS
  Our results demonstrate successful monitoring of brain function during realistic social interactions by NIRS as well as lesser brain activation in the left STS during face-to-face conversations in typically developed participants with higher levels of autistic traits.
authors.affiliation: Department of Psychiatry and Neuroscience, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Suda
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takei
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Aoyama
authors.forename: Kosuke
authors.initials: K
authors.lastname: Narita
authors.forename: Noriko
authors.initials: N
authors.lastname: Sakurai
authors.forename: Masato
authors.initials: M
authors.lastname: Fukuda
authors.forename: Masahiko
authors.initials: M
authors.lastname: Mikuni
mesh_terms: D000328:Adult; D001321:Autistic Disorder / Q000503:physiopathology*; D001931:Brain Mapping; D003142:Communication; D005145:Face; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D019655:Quantitative Trait, Heritable; D013647:Task Performance and Analysis; D055815:Young Adult
chemical_list: D006454:Hemoglobins