Effects of mild hypoxic hypoxia on poststimulus undershoot of blood-oxygenation-level-dependent fMRI signal in the human visual cortex

2006 ◽  
Vol 24 (8) ◽  
pp. 993-999 ◽  
Author(s):  
Pasi I. Tuunanen ◽  
Rishma Vidyasagar ◽  
Risto A. Kauppinen
Keyword(s):  
Visual Cortex ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Hypoxic Hypoxia ◽  
Human Visual Cortex ◽  
Fmri Signal ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

Blood oxygenation level-dependent (BOLD) total and extravascular signal changes and ΔR 2 * in human visual cortex at 1.5, 3.0 and 7.0 T

2010 ◽  
Vol 24 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Manus J. Donahue ◽  
Hans Hoogduin ◽  
Peter C. M. van Zijl ◽  
Peter Jezzard ◽  
Peter R. Luijten ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Human Visual Cortex ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Signal Changes

scholarly journals Dynamic metabolic changes in human visual cortex in regions with positive and negative blood oxygenation level-dependent response

2018 ◽  
Vol 39 (11) ◽  
pp. 2295-2307 ◽  
Author(s):  
Miguel Martínez-Maestro ◽  
Christian Labadie ◽  
Harald E Möller
Keyword(s):  
Visual Cortex ◽  
Tricarboxylic Acid Cycle ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Metabolic Changes ◽  
Resonance Spectroscopy ◽  
Bold Response ◽  
Full Field ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

Dynamic metabolic changes were investigated by functional magnetic resonance spectroscopy (fMRS) during sustained stimulation of human primary visual cortex. Two established paradigms, consisting of either a full-field or a small-circle flickering checkerboard, were employed to generate wide-spread areas of positive or negative blood oxygenation level-dependent (BOLD) responses, respectively. Compared to baseline, the glutamate concentration increased by 5.3% ( p = 0.007) during activation and decreased by −3.8% ( p = 0.017) during deactivation. These changes were positively correlated with the amplitude of the BOLD response ( R = 0.60, p = 0.002) and probably reflect changes of tricarboxylic acid cycle activity. During deactivation, the glucose concentration decreased by −7.9% ( p = 0.025) presumably suggesting increased consumption or reduced glucose supply. Other findings included an increased concentration of glutathione (4.2%, p = 0.023) during deactivation and a negative correlation of glutathione and BOLD signal changes ( R = −0.49, p = 0.012) as well as positive correlations of aspartate ( R = 0.44, p = 0.035) and N-acetylaspartylglutamate ( R = 0.42, p = 0.035) baseline concentrations with the BOLD response. It remains to be shown in future work if the observed effects on glutamate and glucose levels deviate from the assumption of a direct link between glucose utilization and regulation of blood flow or support previous suggestions that the hemodynamic response is mainly driven by feedforward release of vasoactive messengers.

scholarly journals BOLD-Perfusion Coupling during Monocular and Binocular Stimulation

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Claudine Gauthier ◽  
Richard D. Hoge
Keyword(s):  
Visual Cortex ◽  
Oxidative Metabolism ◽  
Visual Stimulation ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Bold Signal ◽  
Blood Oxygenation Level ◽  
Monocular Stimulation ◽  
Binocular Stimulation ◽  
Oxygenation Level

Previous studies have suggested that during selective activation of a subset of the zones comprising a columnar system in visual cortex, perfusion increases uniformly in all columns of the system, while increases in oxidative metabolism occur predominantly in the activated columns. This could lead to disproportionately large blood oxygenation level-dependent (BOLD) signal increases for a given flow increase during monocular (relative to binocular) stimulation, due to contributions from columns which undergo large increases in perfusion with little or no change in oxidative metabolism. In the present study, we sought to test this hypothesis by measuring BOLD-perfusion coupling ratios in spatially averaged signals over V1 during monocular and binocular visual stimulation. It was found that, although withholding input to one eye resulted in statistically significant decreases in BOLD and perfusion signals in primary visual cortex, the ratio between BOLD and perfusion increases did not change significantly. These results do not support a gross mismatch between spatial patterns of flow and metabolism response during monocular stimulation.

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