scholarly journals A Model of the Dynamic Relationship between Blood Flow and Volume Changes during Brain Activation

2004 ◽  
Vol 24 (12) ◽  
pp. 1382-1392 ◽  
Author(s):  
Yazhuo Kong ◽  
Ying Zheng ◽  
David Johnston ◽  
John Martindale ◽  
Myles Jones ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Volume ◽  
Temporal Dynamics ◽  
Blood Oxygen Level Dependent ◽  
Extended Model ◽  
Biophysical Modeling ◽  
Blood Oxygen Level ◽  
Windkessel Model ◽  
Dynamic Relationship ◽  
Dependent Signal

The temporal relationship between changes in cerebral blood flow (CBF) and cerebral blood volume (CBV) is important in the biophysical modeling and interpretation of the hemodynamic response to activation, particularly in the context of magnetic resonance imaging and the blood oxygen level–dependent signal. Grubb et al. (1974) measured the steady state relationship between changes in CBV and CBF after hypercapnic challenge. The relationship CBVαCBFΦ has been used extensively in the literature. Two similar models, the Balloon ( Buxton et al., 1998 ) and the Windkessel ( Mandeville et al., 1999 ), have been proposed to describe the temporal dynamics of changes in CBV with respect to changes in CBF. In this study, a dynamic model extending the Windkessel model by incorporating delayed compliance is presented. The extended model is better able to capture the dynamics of CBV changes after changes in CBF, particularly in the return-to-baseline stages of the response.

scholarly journals Measurement of CMRO2 and its relationship with CBF in hypoxia with an extended calibrated BOLD method

2019 ◽  
Vol 40 (10) ◽  
pp. 2066-2080
Author(s):  
Yaoyu Zhang ◽  
Yayan Yin ◽  
Huanjie Li ◽  
Jia-Hong Gao
Keyword(s):  
Cerebral Blood Volume ◽  
Pulse Sequence ◽  
Blood Oxygen Level Dependent ◽  
Extended Model ◽  
Brain Health ◽  
Blood Oxygen Level ◽  
Oxygen Conditions ◽  
Health And Disease ◽  
The Brain ◽  
Mild Hypoxia

Cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) are physiological parameters that not only reflect brain health and disease but also jointly contribute to blood oxygen level-dependent (BOLD) signals. Nevertheless, unsolved issues remain concerning the CBF–CMRO2 relationship in the working brain under various oxygen conditions. In particular, the CMRO2 responses to functional tasks in hypoxia are less studied. We extended the calibrated BOLD model to incorporate CMRO2 measurements in hypoxia. The extended model, which was cross-validated with a multicompartment BOLD model, considers the influences of the reduced arterial saturation level and increased baseline cerebral blood volume (CBV) and deoxyhemoglobin concentration on the changes of BOLD signals in hypoxia. By implementing a pulse sequence to simultaneously acquire the CBV-, CBF- and BOLD-weighted signals, we investigated the effects of mild hypoxia on the CBF and CMRO2 responses to graded visual stimuli. Compared with normoxia, mild hypoxia caused significant alterations in both the amplitude and the trend of the CMRO2 responses but did not impact the corresponding CBF responses. Our observations suggested that the flow-metabolism coupling strategies in the brain during mild hypoxia were different from those during normoxia.

scholarly journals Relationship Between Changes in the Temporal Dynamics of the Blood-Oxygen-Level-Dependent Signal and Hypoperfusion in Acute Ischemic Stroke

Stroke ◽  
2017 ◽  
Vol 48 (4) ◽  
pp. 925-931 ◽  
Author(s):  
Ahmed A. Khalil ◽  
Ann-Christin Ostwaldt ◽  
Till Nierhaus ◽  
Ramanan Ganeshan ◽  
Heinrich J. Audebert ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Temporal Dynamics ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
Dependent Signal

Motor network recovery in patients with chronic spinal cord compression: a longitudinal study following decompression surgery

2018 ◽  
Vol 28 (4) ◽  
pp. 379-388 ◽  
Author(s):  
Kayla Ryan ◽  
Sandy Goncalves ◽  
Robert Bartha ◽  
Neil Duggal
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Compression ◽  
Surgical Intervention ◽  
Blood Oxygen Level Dependent ◽  
Cord Compression ◽  
Decompression Surgery ◽  
Blood Oxygen Level ◽  
Motor Network ◽  
Dependent Signal

OBJECTIVEThe authors used functional MRI to assess cortical reorganization of the motor network after chronic spinal cord compression and to characterize the plasticity that occurs following surgical intervention.METHODSA 3-T MRI scanner was used to acquire functional images of the brain in 22 patients with reversible cervical spinal cord compression and 10 control subjects. Controls performed a finger-tapping task on 3 different occasions (baseline, 6-week follow-up, and 6-month follow-up), whereas patients performed the identical task before surgery and again 6 weeks and 6 months after spinal decompression surgery.RESULTSAfter surgical intervention, an increased percentage blood oxygen level–dependent signal and volume of activation was observed within the contralateral and ipsilateral motor network. The volume of activation of the contralateral primary motor cortex was associated with functional measures both at baseline (r = 0.55, p < 0.01) and 6 months after surgery (r = 0.55, p < 0.01). The percentage blood oxygen level–dependent signal of the ipsilateral supplementary motor area 6 months after surgery was associated with increased function 6 months after surgery (r = 0.48, p < 0.01).CONCLUSIONSPlasticity of the contralateral and ipsilateral motor network plays complementary roles in maintaining neurological function in patients with spinal cord compression and may be critical in the recovery phase following surgery.

scholarly journals Aberrant blood-oxygen-level-dependent signal oscillations across frequency bands characterize the alcoholic brain

2017 ◽  
Vol 23 (2) ◽  
pp. 824-835 ◽  
Author(s):  
Jui-Yang Hong ◽  
Eva M. Müller-Oehring ◽  
Adolf Pfefferbaum ◽  
Edith V. Sullivan ◽  
Dongjin Kwon ◽  
...  
Keyword(s):  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
Frequency Bands ◽  
Dependent Signal

scholarly journals BOLD and Perfusion Response to Finger-Thumb Apposition after Acetazolamide Administration: Differential Relationship to Global Perfusion

2003 ◽  
Vol 23 (7) ◽  
pp. 829-837 ◽  
Author(s):  
Gregory G. Brown ◽  
Lisa T. Eyler Zorrilla ◽  
Bassem Georgy ◽  
Sandra S. Kindermann ◽  
Eric C. Wong ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Blood Oxygen Level Dependent ◽  
Bold Response ◽  
Blood Oxygen Level ◽  
Individual Subject ◽  
Cerebrovascular Reserve ◽  
Global Cerebral Blood Flow ◽  
Hand Area ◽  
Cortical Perfusion

The authors studied the effects of altering global cerebral blood flow on both blood oxygen level–dependent (BOLD) response and perfusion response to finger-thumb apposition. A PICORE/QUIPSS II protocol was used to collect interleaved BOLD-weighted and perfusion-weighted images on eight finger-thumb apposition trials. Subjects were studied on a drug-free day and on a day when acetazolamide was administered between the second and third trials. After acetazolamide administration, resting cortical perfusion increased an average of 20% from preadministration levels, whereas the BOLD response to finger-thumb apposition decreased by an average of 35% in the S1M1 hand area. Contrary to predictions from the exhausted cerebrovascular reserve hypothesis and the oxygen limitation model, an effect of acetazolamide on cerebral blood flow response in the S1M1 hand area was not observed. Across the acetazolamide trials, BOLD response was inversely correlated with resting cortical perfusion for individual subject data. These results suggest that resting perfusion affects the magnitude of the BOLD response and is thus an important confounding factor in fMRI studies, and that the physiologic systems that increase cerebral blood flow in response to acetazolamide administration and systems that increase cerebral blood flow in response to altered neural activity appear to have additive effects.

scholarly journals fMRI of the rod scotoma elucidates cortical rod pathways and implications for lesion measurements

2015 ◽  
Vol 112 (16) ◽  
pp. 5201-5206 ◽  
Author(s):  
Brian Barton ◽  
Alyssa A. Brewer
Keyword(s):  
Blood Oxygen Level Dependent ◽  
Cortical Reorganization ◽  
Blood Oxygen Level ◽  
Short Term ◽  
Traumatic Lesion ◽  
Electrophysiological Studies ◽  
Short Term Adaptation ◽  
Early Visual Cortex ◽  
Dependent Signal

Are silencing, ectopic shifts, and receptive field (RF) scaling in cortical scotoma projection zones (SPZs) the result of long-term reorganization (plasticity) or short-term adaptation? Electrophysiological studies of SPZs after retinal lesions in animal models remain controversial, because they are unable to conclusively answer this question because of limitations of the methodology. Here, we used functional MRI (fMRI) visual field mapping through population RF (pRF) modeling with moving bar stimuli under photopic and scotopic conditions to measure the effects of the rod scotoma in human early visual cortex. As a naturally occurring central scotoma, it has a large cortical representation, is free of traumatic lesion complications, is completely reversible, and has not reorganized under normal conditions (but can as seen in rod monochromats). We found that the pRFs overlapping the SPZ in V1, V2, V3, hV4, and VO-1 generally (i) reduced their blood oxygen level-dependent signal coherence and (ii) shifted their pRFs more eccentric but (iii) scaled their pRF sizes in variable ways. Thus, silencing, ectopic shifts, and pRF scaling in SPZs are not unique identifiers of cortical reorganization; rather, they can be the expected result of short-term adaptation. However, are there differences between rod and cone signals in V1, V2, V3, hV4, and VO-1? We did not find differences for all five maps in more peripheral eccentricities outside of rod scotoma influence in coherence, eccentricity representation, or pRF size. Thus, rod and cone signals seem to be processed similarly in cortex.

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