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 Simultaneous Blood Oxygenation Level-Dependent and Cerebral Blood Flow Functional Magnetic Resonance Imaging during Forepaw Stimulation in the Rat

1999 ◽  
Vol 19 (8) ◽  
pp. 871-879 ◽  
Author(s):  
Afonso C. Silva ◽  
Sang-Pil Lee ◽  
Guang Yang ◽  
Costantino Iadecola ◽  
Seong-Gi Kim
Keyword(s):  
Correlation Coefficient ◽  
Cerebral Blood Volume ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Single Shot ◽  
Bold Signal ◽  
Doppler Flowmetry ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Signal Changes

The blood oxygenation level-dependent (BOLD) contrast mechanism can be modeled as a complex interplay between CBF, cerebral blood volume (CBV), and CMRO2. Positive BOLD signal changes are presumably caused by CBF changes in excess of increases in CMRO2. Because this uncoupling between CBF and CMRO2 may not always be present, the magnitude of BOLD changes may not be a good index of CBF changes. In this study, the relation between BOLD and CBF was investigated further. Continuous arterial spin labeling was combined with a single-shot, multislice echo-planar imaging to enable simultaneous measurements of BOLD and CBF changes in a well-established model of functional brain activation, the electrical forepaw stimulation of a-chloralose-anesthetized rats. The paradigm consisted of two 18- to 30-second stimulation periods separated by a 1-minute resting interval. Stimulation parameters were optimized by laser Doppler flowmetry. For the same cross-correlation threshold, the BOLD and CBF active maps were centered within the size of one pixel (470 µm). However, the BOLD map was significantly larger than the CBF map. Measurements taken from 15 rats at 9.4 T using a 10-millisecond echo-time showed 3.7 ± 1.7% BOLD and 125.67 ± 81.7% CBF increases in the contralateral somatosensory cortex during the first stimulation, and 2.6 ± 1.2% BOLD and 79.3 ± 43.6% CBF increases during the second stimulation. The correlation coefficient between BOLD and CBF changes was 0.89. The overall temporal correlation coefficient between BOLD and CBF time-courses was 0.97. These results show that under the experimental conditions of the current study, the BOLD signal changes follow the changes in CBF.

Sign in / Sign up

Export Citation Format

Share Document