title: Ethnic influences on neurovascular coupling: a pilot study in whites and Asians.
abstract: OBJECTIVE
  An ethnic extraintracranial difference in atherosclerosis has been well reported, whereas the potential mechanism remains unclear. We aimed to investigate neurovascular coupling in healthy whites and Asians.
  
  
  METHODS
  Twenty volunteers of each ethnicity were recruited to perform a functional transcranial Doppler examination with standardized checkerboard patterns as visual stimulation (3 x 4, 6 x 8, and 12 x 16 checks subtending a visual field section of 18 degrees x 24 degrees , flicker rate 1 Hz). Hemodynamic responses in both posterior cerebral arteries were evaluated with a control system approach.
  
  
  RESULTS
  The rate time, that is, the initial speed of flow velocity adaptation, was significantly lower in Asians leading to an approximately 2-second delayed hemodynamic adaptation. The other hemodynamic parameters and the dependency of hemodynamic responses in regard to the complexity degree of the stimulus were similar between groups.
  
  
  CONCLUSIONS
  The constellation suggests a greater initial mismatch between functionally increased metabolic demand of neurons and adjusted cerebral blood flow in Asians.
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Hao
authors.forename: Lawrence K S
authors.initials: LK
authors.lastname: Wong
authors.forename: Wen Hua
authors.initials: WH
authors.lastname: Lin
authors.forename: Thomas W H
authors.initials: TW
authors.lastname: Leung
authors.forename: Manfred
authors.initials: M
authors.lastname: Kaps
authors.forename: Bernhard
authors.initials: B
authors.lastname: Rosengarten
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D044466:Asian People; D001921:Brain / Q000098:blood supply / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002561:Cerebrovascular Disorders / Q000208:ethnology / Q000235:genetics / Q000503:physiopathology; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D020022:Genetic Predisposition to Disease / Q000208:ethnology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D010865:Pilot Projects; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging* / Q000502:physiology*; D044469:Racial Groups; D011930:Reaction Time / Q000502:physiology; D017585:Ultrasonography, Doppler, Transcranial; D044465:White People; D055815:Young Adult