On the Use of Caffeine as a Contrast Booster for BOLD fMRI Studies

Mulderink, Todd; Gitelman, Darren R.; Mesulam, M. Marsel; Parrish, Todd B.

doi:10.1006/nimg.2001.0973

Cited by 157 publications

(143 citation statements)

References 31 publications

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“…However, previous studies have shown that preconstriction of the cerebral vasculature can enhance the BOLD response evoked by somatosensory stimulation (Mulderink et al . 2002). Interestingly, it has been shown that SHRs display increased vertebrobasilar artery remodeling and constriction (Cates et al .…”

Section: Discussionmentioning

confidence: 99%

Abnormal oxygen homeostasis in the nucleus tractus solitarii of the spontaneously hypertensive rat

Hosford

Millar

Ramage

et al. 2017

Experimental Physiology

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New Findings What is the central question of this study? Arterial hypertension is associated with impaired neurovascular coupling in the somatosensory cortex. Abnormalities in activity‐dependent oxygen consumption in brainstem regions involved in the control of cardiovascular reflexes have not been explored previously. What is the main finding and its importance? Using fast‐cyclic voltammetry, we found that changes in local tissue PnormalO2 in the nucleus tractus solitarii induced by electrical stimulation of the vagus nerve are significantly impaired in spontaneously hypertensive rats. This is consistent with previous observations showing that brainstem hypoxia plays an important role in the pathogenesis of arterial hypertension. The effects of arterial hypertension on cerebral blood flow remain poorly understood. Haemodynamic responses within the somatosensory cortex have been shown to be impaired in the spontaneously hypertensive rat (SHR) model. However, it is unknown whether arterial hypertension affects oxygen homeostasis in vital brainstem areas that control cardiovascular reflexes. In this study, we assessed vagus nerve stimulation‐induced changes in local tissue PnormalO2 (PnormaltO2) in the caudal nucleus tractus solitarii (cNTS) of SHRs and normotensive Wistar rats. Measurements of PnormaltO2 were performed using a novel application of fast‐cyclic voltammetry, which allows higher temporal resolution of O2 changes than traditional optical fluorescence techniques. Electrical stimulation of the central cut end of the vagus nerve (ESVN) caused profound reductions in arterial blood pressure along with biphasic changes in PnormaltO2 in the cNTS, characterized by a rapid decrease in PnormaltO2 (‘initial dip’) followed by a post‐stimulus overshoot above baseline. The initial dip was found to be significantly smaller in SHRs compared with normotensive Wistar rats even after ganglionic blockade. The post‐ESVN overshoot was similar in both groups but was reduced in Wistar rats after ganglionic blockade. In conclusion, neural activity‐dependent changes in tissue oxygen in brainstem cardiovascular autonomic centres are significantly impaired in animals with arterial hypertension.

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Section: Discussionmentioning

confidence: 99%

Abnormal oxygen homeostasis in the nucleus tractus solitarii of the spontaneously hypertensive rat

Hosford

Millar

Ramage

et al. 2017

Experimental Physiology

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“…Furthermore, differences in cardiac and respiratory induced noise and true differences in the BOLD signal e.g. due to different levels of hormones or drugs such as caffeine (Mulderink et al, 2002) may also contribute to the inter-session variance in fMRI.…”

Section: Discussionmentioning

confidence: 99%

Motion or activity: their role in intra- and inter-subject variation in fMRI

Lund¹,

Nørgaard²,

Rostrup³

et al. 2005

NeuroImage

212

157

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Functional MRI (fMRI) carries the potential for non-invasive measurements of brain activity. Typically what are referred to as activation images are actually thresholded statistical parametric maps. These maps possess large inter-session variability. This is especially problematic when applying fMRI to pre-surgical planning because of a higher requirement for intra-subject precision. The purpose of this study was to investigate the impact of residual movement artefacts on intra-subject and intersubject variability in the observed fMRI activation. Ten subjects were examined using three different word-generation tasks. Two of the subjects were examined 10 times on 10 different days using the same paradigms. We systematically investigated one approach of correcting for residual movement effects: the inclusion of regressors describing movement-related effects in the design matrix of a General Linear Model (GLM). The data were analysed with and without modeling the residual movement artefacts and the impact on inter-session variance was assessed using F-contrasts. Inclusion of motion parameters in the analysis significantly reduced both the intrasubject as well as the inter-subject-variance.

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“…The proportional hypothesis states that the stimulus-evoked fMRI change is proportional to the basal CBF or tissue oxygenation, resulting in a constant relative CBF or BOLD change (Cohen et al, 2002;Shimosegawa et al, 1995). Recently, models describing a more complex dependence of BOLD on baseline CBF (Mulderink et al, 2002) and a "feed-forward" mechanism for neurovascular coupling (Uludag et al, 2003) have been proposed to account for the confounding effects of global CBF and BOLD signals on the stimulus-evoked fMRI responses. However, these previous studies measured only relative BOLD (Cohen et al, 2002;Friston et al, 1990;Ramsay et al, 1993;Shimosegawa et al, 1995) and/or relative CBF (Hoge et al, 1999;Li et al, 2000) changes, and thus their conclusions were indirect.…”

Section: Additive Versus Proportional Hypothesismentioning

confidence: 99%

Effects of hypoxia, hyperoxia, and hypercapnia on baseline and stimulus-evoked BOLD, CBF, and CMRO2 in spontaneously breathing animals

2005

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Functional magnetic resonance imaging (fMRI) was used to investigate the effects of inspired hypoxic, hyperoxic, and hypercapnic gases on baseline and stimulus-evoked changes in blood oxygenation level-dependent (BOLD) signals, cerebral blood flow (CBF), and the cerebral metabolic rate of oxygen (CMRO 2 ) in spontaneously breathing rats under isoflurane anesthesia. Each animal was subjected to a baseline period of six inspired gas conditions (9% O 2 , 12% O 2 , 21% O 2 , 100% O 2 , 5% CO 2 , and 10% CO 2 ) followed by a superimposed period of forepaw stimulation. Significant stimulus-evoked fMRI responses were found in the primary somatosensory cortices. Relative fMRI responses to forepaw stimulation varied across gas conditions and were dependent on baseline physiology, whereas absolute fMRI responses were similar across moderate gas conditions (12% O 2 , 21% O 2 100% O 2 , and 5% CO 2 ) and were relatively independent of baseline physiology. Consistent with data obtained using well-established techniques, baseline and stimulus-evoked CMRO 2 were invariant across moderate physiological perturbations thereby supporting a CMRO 2 -fMRI technique for non-invasive CMRO 2 measurement. However, under 9% O 2 and 10% CO 2 , stimulus-evoked CBF and BOLD were substantially reduced and the CMRO 2 formalism appeared invalid, likely due to attenuated neurovascular coupling and/or a failure of the model under extreme physiological perturbations. These findings demonstrate that absolute fMRI measurements help distinguish neural from non-neural contributions to the fMRI signals and may lend a more accurate measure of brain activity during states of altered basal physiology. Moreover, since numerous pharmacologic agents, pathophysiological states, and psychiatric conditions alter baseline physiology independent of neural activity, these results have implications for neuroimaging studies using relative fMRI changes to map brain activity.

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On the Use of Caffeine as a Contrast Booster for BOLD fMRI Studies

Cited by 157 publications

References 31 publications

Abnormal oxygen homeostasis in the nucleus tractus solitarii of the spontaneously hypertensive rat

Abnormal oxygen homeostasis in the nucleus tractus solitarii of the spontaneously hypertensive rat

Motion or activity: their role in intra- and inter-subject variation in fMRI

Effects of hypoxia, hyperoxia, and hypercapnia on baseline and stimulus-evoked BOLD, CBF, and CMRO2 in spontaneously breathing animals

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