The BOLD response and vascular reactivity during visual stimulation in the presence of hypoxic hypoxia

Yi Ching L. Ho, Rishma Vidyasagar, Yuji Shen, George M. Balanos, Xavier Golay, Risto A. Kauppinen

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


A disproportionate increase in cerebral blood flow (CBF) relative to the cerebral metabolic rate of oxygen (CMRO2), in response to neuronal activation, results in a decreased oxygen extraction fraction (OEF) and hence local 'hyperoxygenation'. The mismatch is the key 'physiological substrate' for blood oxygenation level dependent (BOLD) fMRI. The mismatch may reflect inefficient O2 diffusion in the brain tissue, a factor requiring maintenance of a steep [O2] gradient between capillary bed and neural cell mitochondria. The aim of this study was to assess vascular responsiveness to reduced blood oxygen saturation, using both BOLD fMRI and the CBV-weighted vascular space occupancy (VASO)-dependent fMRI technique, during visual activation in hypoxic hypoxia. Our fMRI results show decreased amplitude and absence of initial sharp overshoot in the BOLD response, while VASO signal was not influenced by decreasing oxygen saturation down to 0.85. The results suggest that the OEF during visual activation may be different in hypoxia relative to normoxia, due to a more efficient oxygen extraction under compromised oxygen availability. The data also indicate that vascular reactivity to brain activation is not affected by mild hypoxia.

Original languageEnglish (US)
Pages (from-to)179-188
Number of pages10
Issue number2
StatePublished - Jun 2008


  • BOLD
  • Hypoxia
  • Oxygen limitation
  • VASO
  • Vascular reactivity
  • Visual
  • fMRI

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience


Dive into the research topics of 'The BOLD response and vascular reactivity during visual stimulation in the presence of hypoxic hypoxia'. Together they form a unique fingerprint.

Cite this