title: Relation between parametric change of the workload and prefrontal cortex activity during a modified version of the 'rock, paper, scissors' task.
abstract: OBJECTIVE
  Modified rock, paper, scissors (RPS) tasks have previously been used in neuroscience to investigate activity of the prefrontal cortex (PFC). In this study, we investigated hemodynamic changes in the PFC using near-infrared spectroscopy (NIRS) during a modified RPS task in which each subject's successful performance rate was equalized; the workload was increased parametrically in order to reveal the resulting pattern of PFC activation.
  
  
  METHODS
  The subjects were 20 healthy adults. During RPS, the player uses hand gestures to represent rock, paper, and scissors. Rock beats scissors, paper beats rock, and scissors beats paper. In the modified RPS task, the player is instructed to lose intentionally against the computer hand; the computer goes first and the player follows. The interstimulus interval (ISI) level was adjusted with 11 steps. If the level rose, the ISI decreased and the workload increased parametrically. The maximal level (maxLv: the shortest ISI and the biggest workload) in which a subject could perform the task correctly was determined for every subject during rehearsal of the task prior to the experiment. Lowering the level from the maxLv made the task easier. Hemodynamic changes were measured by NIRS over 4 task levels (maxLv-3, maxLv-2, maxLv-1 and maxLv).
  
  
  RESULTS
  The hemodynamic changes in the left lateral PFC and bilateral Brodmann area 6 rose significantly with the increase in workload and presented a linear trend.
  
  
  CONCLUSIONS
  These results suggest that PFC activation may linearly increase with increased workload during a modified RPS task in which successful performance rates of subjects are equalized.
authors.affiliation: Department of Psychiatry, Jichi Medical University, Shimotsuke, Japan. yskyamauchi @ jichi.ac.jp
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Yamauchi
authors.forename: Senichiro
authors.initials: S
authors.lastname: Kikuchi
authors.forename: Fumikazu
authors.initials: F
authors.lastname: Miwakeichi
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Masaki
authors.initials: M
authors.lastname: Nishida
authors.forename: Makio
authors.initials: M
authors.lastname: Ishiguro
authors.forename: Eiju
authors.initials: E
authors.lastname: Watanabe
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kato
mesh_terms: D000328:Adult; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D059906:Neuroimaging; D010108:Oxyhemoglobins / Q000378:metabolism; D017397:Prefrontal Cortex / Q000098:blood supply / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D016526:Workload / Q000523:psychology*
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin