A Primer on Functional Magnetic Resonance Imaging

Brown, Gregory G.; Perthen, Joanna E.; Liu, Thomas T.; Buxton, Richard B.

doi:10.1007/s11065-007-9028-8

Cited by 62 publications

(61 citation statements)

References 84 publications

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“…The calibrated-BOLD method offers a potentially powerful paradigm for fMRI by providing a quantitative probe of brain physiology (discussed further in (Brown et al, 2007)). Previously, St Lawrence and colleagues (St Lawrence et al, 2003) used the calibrated-BOLD approach to investigate the effects of a drug, indomethacin, on CBF and CMRO 2 responses to motor activation.…”

Section: Discussionmentioning

confidence: 99%

Caffeine-induced uncoupling of cerebral blood flow and oxygen metabolism: A calibrated BOLD fMRI study

et al. 2008

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Although functional MRI (fMRI) based on blood oxygenation-level dependent (BOLD) signal changes is a sensitive tool for mapping brain activation, quantitative studies of the physiological effects of pharmacological agents using fMRI alone are difficult to interpret due to the complexities inherent in the BOLD response. Hypercapnia calibrated-BOLD methodology is potentially a more powerful physiological probe of brain function, providing measures of the changes in cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen (CMRO 2 ). In this study, we implemented a quantitative R 2 * approach for assessing the BOLD response to improve the stability of repeated measurements, in combination with the calibrated-BOLD method, to examine the CBF and CMRO 2 responses to caffeine ingestion. Ten regular caffeine consumers were imaged before and after a 200mg caffeine dose. A dual echo arterial spin labeling technique was used to measure CBF and BOLD responses to visual stimulation, caffeine consumption and mild hypercapnia. For a region of interest defined by CBF activation to the visual stimulus, the results were: hypercapnia increased CBF (+46.6%, ±11.3, mean and standard error), visual stimulation increased both CBF (+47.9%, ±2.9) and CMRO 2 (+20.7%, ±1.4), and caffeine decreased CBF (-34.5%, ±2.6) with a non-significant change in CMRO 2 (+5.2%, ±6.4). The coupling between CBF and CMRO 2 was significantly different in response to visual stimulation compared to caffeine consumption. A calibrated-BOLD methodology using R 2 * is a promising approach for evaluating CBF and CMRO 2 changes in response to pharmacological interventions. Keywordsfunctional magnetic resonance imaging (fMRI); blood oxygenation level dependent (BOLD); cerebral blood flow (CBF); cerebral metabolic rate of oxygen (CMRO2); calibrated-BOLD; caffeine

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Section: Discussionmentioning

confidence: 99%

Caffeine-induced uncoupling of cerebral blood flow and oxygen metabolism: A calibrated BOLD fMRI study

et al. 2008

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“…Our preliminary work in this area (for reviews, see Brown et al, 2007;Wierenga and Bondi, 2007) suggests that aging results in differences in baseline cerebral blood volume or differences in baseline 0 2 extraction fraction. According to the deoxyhemoglobin dilution model (see Brown et al, 2007, for discussion), BOLD contrast can give misleading information about the underlying metabolic activity of neurons when differences in baseline CBV or CMRO 2 are present.…”

Section: Discussionmentioning

confidence: 99%

“…According to the deoxyhemoglobin dilution model (see Brown et al, 2007, for discussion), BOLD contrast can give misleading information about the underlying metabolic activity of neurons when differences in baseline CBV or CMRO 2 are present. There is an inherent ambiguity of interpreting BOLD response in isolation, especially in the presence of influencing factors such as age, disease, or disease risk.…”

Section: Discussionmentioning

confidence: 99%

Differential age effects on cerebral blood flow and BOLD response to encoding: Associations with cognition and stroke risk

Bangen

Restom

Liu

et al. 2009

Neurobiology of Aging

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Changes in the cerebrovascular system due to age or disease can significantly alter the bloodoxygenation-level-dependent (BOLD) signal and complicate its interpretation. The simultaneous acquisition of arterial spin labeling (ASL) and BOLD data represents a useful technique to more fully characterize the neurovascular underpinnings of functional brain response to cognition. We conducted a functional magnetic resonance imaging (FMRI) study of episodic memory encoding to investigate whether age is related to cerebral blood flow (CBF) and BOLD response in the medial temporal lobe (MTL). Results demonstrated a significant reduction in resting state CBF in older compared to young adults. Conversely, older adults showed significantly increased CBF but not BOLD response in the MTL during picture encoding relative to young adults. Correlations between CBF response and cognition were demonstrated whereas associations with BOLD were not observed. Stroke risk was associated with both CBF and BOLD response. Results suggest that aging effects on CBF and BOLD responses to encoding are dissociable and that cerebrovascular alterations contribute to findings of age-related differences.

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“…BOLD fMRI has been used extensively to investigate functional localization of neural activity associated with cognitive tasks or sensory processing. The BOLD signal, however, is only indirectly related to neural activity via a complex interplay of several factors including cerebral blood flow, cerebral blood volume, and cerebral metabolic rate of oxygen (D'Esposito et al, 2003;Brown et al, 2007;Logothetis, 2008). Thus, great caution is needed when inferring changes in neural activity from the temporal dynamics of the BOLD signal (Logothetis, 2008).…”

Section: Introductionmentioning

confidence: 99%

The Amplitude and Timing of the BOLD Signal Reflects the Relationship between Local Field Potential Power at Different Frequencies

et al. 2012

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There is growing evidence that several components of the mass neural activity contributing to the local field potential (LFP) can be partly separated by decomposing the LFP into nonoverlapping frequency bands. Although the blood oxygen level-dependent (BOLD) signal has been found to correlate preferentially with specific frequency bands of the LFP, it is still unclear whether the BOLD signal relates to the activity expressed by each LFP band independently of the others or if, instead, it also reflects specific relationships among different bands. We investigated these issues by recording, simultaneously and with high spatiotemporal resolution, BOLD signal and LFP during spontaneous activity in early visual cortices of anesthetized monkeys (Macaca mulatta). We used information theory to characterize the statistical dependency between BOLD and LFP. We found that the alpha (8 -12 Hz), beta (18 -30 Hz), and gamma (40 -100 Hz) LFP bands were informative about the BOLD signal. In agreement with previous studies, gamma was the most informative band. Both increases and decreases in BOLD signal reliably followed increases and decreases in gamma power. However, both alpha and beta power signals carried information about BOLD that was largely complementary to that carried by gamma power. In particular, the relationship between alpha and gamma power was reflected in the amplitude of the BOLD signal, while the relationship between beta and gamma bands was reflected in the latency of BOLD with respect to significant changes in gamma power. These results lay the basis for identifying contributions of different neural pathways to cortical processing using fMRI.

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A Primer on Functional Magnetic Resonance Imaging

Cited by 62 publications

References 84 publications

Caffeine-induced uncoupling of cerebral blood flow and oxygen metabolism: A calibrated BOLD fMRI study

Caffeine-induced uncoupling of cerebral blood flow and oxygen metabolism: A calibrated BOLD fMRI study

Differential age effects on cerebral blood flow and BOLD response to encoding: Associations with cognition and stroke risk

The Amplitude and Timing of the BOLD Signal Reflects the Relationship between Local Field Potential Power at Different Frequencies

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