title: Frontal activity during the digit symbol substitution test determined by multichannel near-infrared spectroscopy.
abstract: BACKGROUND
  The digit symbol substitution test (DSST) is a clinically useful and widely accepted tool for the detection of various psychiatric disorders. Investigating neural activity during the DSST is useful when considering the relationship between the poor performance on the DSST and neurocognitive deficits. However, obtaining reliable functional imaging of the neural mechanisms associated with this test is challenging due to motion artifacts.
  
  
  OBJECTIVE
  To circumvent this problem, we examined frontal lobe activity during the DSST using multichannel near-infrared spectroscopy, a noninvasive functional imaging technique that does not interfere with the DSST procedure.
  
  
  METHODS
  Twenty-five healthy volunteers were enrolled in this study. Changes in the concentration of oxygenated hemoglobin (oxyHb) during the DSST were determined bilaterally in 52 measurement points (channels) on the frontal area.
  
  
  RESULTS
  We found significant increases in oxyHb in more than 70% of the channels, with the intensity of the increase being more pronounced in the left hemisphere. Several channels showed significant positive correlations between changes in oxyHb and DSST performance. Some of the channels with a significant increase in oxyHb during the DSST did not show a correlation with the DSST performance.
  
  
  CONCLUSIONS
  Our findings indicate that the DSST could prove useful as a frontal lobe stimulating task. Further examinations of DSST/near-infrared spectroscopy analyses of neural mechanisms in patients with psychiatric and neurological diseases are necessary to assess its effectiveness in clinical practice for the evaluation of neuropsychopathology.
authors.affiliation: Department of Clinical Neuroscience and Psychiatry, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakahachi
authors.forename: Ryouhei
authors.initials: R
authors.lastname: Ishii
authors.forename: Masao
authors.initials: M
authors.lastname: Iwase
authors.forename: Leonides
authors.initials: L
authors.lastname: Canuet
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Takahashi
authors.forename: Ryu
authors.initials: R
authors.lastname: Kurimoto
authors.forename: Kouji
authors.initials: K
authors.lastname: Ikezawa
authors.forename: Michiyo
authors.initials: M
authors.lastname: Azechi
authors.forename: Ryuji
authors.initials: R
authors.lastname: Sekiyama
authors.forename: Eiko
authors.initials: E
authors.lastname: Honaga
authors.forename: Chigusa
authors.initials: C
authors.lastname: Uchiumi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iwakiri
authors.forename: Naoyasu
authors.initials: N
authors.lastname: Motomura
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Takeda
mesh_terms: D000328:Adult; D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D004192:Discrimination, Psychological / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism*; D006801:Humans; D007802:Language; D008297:Male; D009483:Neuropsychological Tests; D010108:Oxyhemoglobins / Q000378:metabolism; D019265:Spectroscopy, Near-Infrared; D055815:Young Adult
chemical_list: D010108:Oxyhemoglobins