title: Hemodynamic changes in the prefrontal cortex during digit span task: a near-infrared spectroscopy study.
abstract: OBJECTIVE
  In this study, we examined changes in the concentrations of oxygenated and deoxygenated hemoglobin (oxy- and deoxy-Hb, respectively) in the prefrontal cortex (PFC) during the digit span task by using near-infrared spectroscopy (NIRS).
  
  
  METHODS
  The digit span task consists of the digit span forward and backward tasks. The tasks were performed by 22 healthy undergraduate students who participated in this study. Differences in the mean concentrations of oxy-Hb and deoxy-Hb between the baseline and task intervals were evaluated.
  
  
  RESULTS
  In digit span backward, oxy-Hb was significantly higher during the task interval than during the baseline. Further, deoxy-Hb was significantly lower during the task interval than during the baseline in both digit span forward and digit span backward. Digit span forward performance was significantly higher for the right-PFC-dominant group than for the left-PFC-dominant group.
  
  
  CONCLUSIONS
  These results suggest that the digit span backward task is more demanding and requires greater activation of the prefrontal cortex than the digit span forward task. Our NIRS findings suggest that the digit span backward task involves executive functioning.
authors.affiliation: Center for Developmental Clinical Psychology and Psychiatry, Nagoya University, Nagoya, Japan. kaneko@cc.nagoya-u.ac.jp
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kaneko
authors.forename: Toru
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Nomura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ito
authors.forename: Hoshiko
authors.initials: H
authors.lastname: Yamauchi
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Ogura
authors.forename: Shuji
authors.initials: S
authors.lastname: Honjo
mesh_terms: D000293:Adolescent; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared; D055815:Young Adult
chemical_list: D006454:Hemoglobins