title: Differential frontal activation during exogenous and endogenous orientation of visuospatial attention. A near-infrared spectroscopy study.
abstract: OBJECTIVE
  The aim was to measure the prefrontal cortical activity involved in shifting spatial attention to visual stimuli in the left or right visual field using near-infrared spectroscopy.
  
  
  METHODS
  Eleven participants performed a simple vigilance task, an endogenous attention task and an exogenous attention task. In the endogenous task, the left or the right side of the center diamond brightened, indicating the side for subsequent target appearance (controlled shift of attention). In the exogenous task, the peripheral squares brightened, indicating the appearance of target in those squares (reflexive shift of attention).
  
  
  RESULTS
  Stimuli at validly cued locations were responded to faster than stimuli at invalidly cued locations. Increases in oxyhemoglobin (oxy-Hb) were observed in the right prefrontal cortex throughout the 3 tasks, and in the left prefrontal cortex during the vigilance and the exogenous tasks. In the exogenous task, marked decreases in oxy-Hb were observed in the bilateral ventrolateral prefrontal cortex.
  
  
  CONCLUSIONS
  These results suggest that the left and the right prefrontal cortices mediate distinct cognitive processes during the performance of visuospatial attentional tasks.
authors.affiliation: Department of Psychology, Asahikawa Medical College, Asahikawa, Japan. takam@asahikawa-med.ac.jp
authors.forename: Masaharu
authors.initials: M
authors.lastname: Takahashi
authors.forename: Masanaga
authors.initials: M
authors.lastname: Ikegami
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D003463:Cues; D005260:Female; D007839:Functional Laterality; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology*; D010108:Oxyhemoglobins / Q000378:metabolism; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D017397:Prefrontal Cortex / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013997:Time Factors; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin