title: Differential activation of cerebral blood flow by stimulating amblyopic and fellow eye.
abstract: OBJECTIVE
  Positron emission tomography (PET), the blood flow response in the primary visual cortex (V1) to two visual stimuli, low temporal frequency (6 Hz) to activate the parvocellular system, and high temporal frequency (25 Hz) to activate the magnocellular system were used to investigate pathophysiologic mechanism of amblyopia.
  
  
  METHODS
  Five women and one man who were aged between 26 and 60 years, who were ophthalmologically normal except for amblyopia, and who had corrected visual acuity in the amblyopic eye of 0.6 or worse were examined. An intravenous injection of the H(2)(15)O was given, and the regional cerebral blood flow was measured by PET during full-field stimulation with either 6 Hz or 25 Hz flicker to the amblyopic or the sound eye.
  
  
  RESULTS
  The activation of blood flow in the contra-lateral area V1 by the 6-Hz stimulation of the sound eye was greater than that during the stimulation of the amblyopic eye (P<0.05, small volume correction, n=6). With 25-Hz stimulation of the sound and amblyopic eyes, the blood flow in the contra-lateral and ipsi-lateral areas V1 was not significantly different.
  
  
  CONCLUSIONS
  The decreased activation of blood flow in the contra-lateral V1 by low temporal frequency stimuli supports the hypothesis that the parvocellular pathway in amblyopic eyes is depressed.
authors.affiliation: Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University Graduate School, Tokyo, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Mizoguchi
authors.forename: Yukihisa
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Motohiro
authors.initials: M
authors.lastname: Kiyosawa
authors.forename: Manabu
authors.initials: M
authors.lastname: Mochizuki
authors.forename: Kenji
authors.initials: K
authors.lastname: Ishii
mesh_terms: D000328:Adult; D000550:Amblyopia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001345:Autoradiography / Q000379:methods; D001921:Brain / Q000098:blood supply*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D018450:Disease Progression; D004585:Electrooculography; D005133:Eye Movements; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D010104:Oxygen Radioisotopes / Q000008:administration & dosage; D049268:Positron-Emission Tomography / Q000379:methods; D012039:Regional Blood Flow / Q000502:physiology*; D015203:Reproducibility of Results; D013268:Stimulation, Chemical; D014792:Visual Acuity; D014867:Water / Q000008:administration & dosage
chemical_list: D010104:Oxygen Radioisotopes; D014867:Water