A Noninvasive Approach to Quantitative Functional Brain Mapping with H<sub>2</sub><sup>15</sup>O and Positron Emission Tomography

Fox, Peter T.; Mintun, Mark A.; Raichle, Marcus E.; Herscovitch, Peter

doi:10.1038/jcbfm.1984.49

Cited by 226 publications

(70 citation statements)

References 4 publications

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“…The recent development of brain-imaging methods, such as positron-emission tomography (PET) and functional magnetic resonance imaging (fMRI), allows researchers to study cortical activity in humans (Fox et al, 1984Bandettini et al, 1992;Kwong et al, 1992;Ogawa et al, 1992). In PET, concentration of a preinjected radioactive substance inside the body is revealed by the scanner.…”

Section: Functional Brain-imaging Studiesmentioning

confidence: 99%

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Functional and cortical adaptations to central vision loss

2005

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Age-related macular degeneration (AMD), affecting the retina, afflicts one out of ten people aged 80 years or older in the United States. AMD often results in vision loss to the central 15-20 deg of the visual field (i.e. central scotoma), and frequently afflicts both eyes. In most cases, when the central scotoma includes the fovea, patients will adopt an eccentric preferred retinal locus (PRL) for fixation. The onset of a central scotoma results in the absence of retinal inputs to corresponding regions of retinotopically mapped visual cortex. Animal studies have shown evidence for reorganization in adult mammals for such cortical areas following experimentally induced central scotomata. However, it is still unknown whether reorganization occurs in primary visual cortex (V1) of AMD patients. Nor is it known whether the adoption of a PRL corresponds to changes to the retinotopic mapping of V1. Two recent advances hold out the promise for addressing these issues and for contributing to the rehabilitation of AMD patients: improved methods for assessing visual function across the fields of AMD patients using the scanning laser ophthalmoscope, and the advent of brain-imaging methods for studying retinotopic mapping in humans. For the most part, specialists in these two areas come from different disciplines and communities, with few opportunities to interact. The purpose of this review is to summarize key findings on both the clinical and neuroscience issues related to questions about visual adaptation in AMD patients.

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Section: Functional Brain-imaging Studiesmentioning

confidence: 99%

“…In PET, concentration of a preinjected radioactive substance inside the body is revealed by the scanner. One of the often-used radioactive substances is water labeled with radioactive oxygen ( 15 O) (Fox et al, 1984). Change in blood flow is marked by the preinjected radioactive water and can be imaged by a PET scanner.…”

Section: Functional Brain-imaging Studiesmentioning

confidence: 99%

Functional and cortical adaptations to central vision loss

2005

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“…Second, when dopamine production outside the brain is adequately inhibited by a peripheral decarboxylase inhibitor like carbidopa, levodopa does not alter global cerebral blood flow [34,36,38]. This characteristic allows us to use qualitative measurements of blood flow such as blood oxygenation level-dependent (BOLD) signal in fMRI to determine the impact of levodopa on brain activity without misrepresenting an absolute change in local flow or neuronal activity [10,15,27]. Local blood flow (and BOLD signal) responses to behavioral or dopaminergic challenges primarily reflect changes in axonal terminal fields or local interneurons [33,44,47,52,67].…”

Section: Introductionmentioning

confidence: 99%

Dopaminergic modulation of response inhibition: an fMRI study

HERSHEY

2004

Cognitive Brain Research

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Dopamine has been hypothesized to modulate response inhibition. To test this hypothesis, we used functional magnetic resonance imaging (fMRI) to measure the effects of the dopamine prodrug levodopa on the brain responses to a well-validated response inhibition task (go/no-go, or GNG). Since abnormalities of response inhibition and dopamine have been thought to underlie tics and other symptoms of Tourette syndrome, we studied 8 neuroleptic-naive adults with tic disorders as well as 10 well-matched healthy controls. Subjects were pretreated with the peripheral decarboxylase inhibitor carbidopa, then scanned during GNG and control blocks, both before and during i.v. levodopa infusion. Both groups had similar task performance and task-related regional brain activity before and during levodopa infusion. Levodopa did not affect reaction times or accuracy, so fMRI findings can be interpreted without concern that they simply reflect a performance difference between conditions. Levodopa did affect the magnitude of GNG-related fMRI responses in the right cerebellum and right parietal cortex, significantly reducing both. Pre-levodopa activity in the right cerebellum correlated with reaction times (higher magnitudes associated with faster reaction times), and pre-levodopa activity in the right parietal cortex correlated with false alarm rate (higher magnitudes associated with higher error). In summary, right parietal and cerebellar regions important in mediating specific aspects of the GNG task were modulated by levodopa, suggesting a region-specific role for dopamine in response inhibition. D 2004 Elsevier B.V. All rights reserved.Theme: Neural basis of behavior Topic: Cognition

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“…Thus each condition (baseline and visual stimulation) covered the time required for whole brain data acquisition. O-15-water is the gold standard PET tracer for measurement of cerebral blood flow, and was used for functional activation studies before fMRI (Fox et al, 1984). O-15-water PET only takes about 3 min per scan, much less time compared to FDG-PET (Hurtig et al, 1994), and due to low radiation exposure (very short tracer half-life) can be repeated several times in the same volunteer.…”

Section: Discussionmentioning

confidence: 99%

“…In this study, we aimed to exploratively validate fQSM with data from a clinical 3T MR scanner and healthy volunteers, to propose a straightforward pipeline for fQSM analyses, and to focus on the phenomenology of volumes with negative correlations. Results from simultaneously acquired fMRI data, from truly quantitative cerebral blood flow (CBF) maps from Position Emission Tomography (PET) (Fox et al, 1984), and simulated data served as standards of reference. Preliminary results have been presented as conference and workshop abstracts (Özbay et al, 2015a; Özbay et al, 2014a; Özbay et al, 2014c).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Probing neuronal activation by functional quantitative susceptibility mapping under a visual paradigm: A group level comparison with BOLD fMRI and PET

et al. 2016

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Dynamic changes of brain-tissue magnetic susceptibility provide the basis for functional MR imaging (fMRI) via T2*-weighted signal-intensity modulations. Promising initial work on a detection of neuronal activity via quantitative susceptibility mapping (fQSM) has been published but consistently reported on ill-understood positive and negative activation patterns (Balla et al., 2014;Chen and Calhoun, 2015a). We set out to (i) demonstrate that fQSM can exploit established fMRI data acquisition and processing methods and to (ii) better describe aspects of the apparent activation patterns using fMRI and PET as standards of reference. Under a standardized visual-stimulation paradigm PET and 3-T gradient-echo EPI-based fQSM, fMRI data from 9 healthy volunteers were acquired and analyzed by means of Independent Component Analysis (ICA) at subject level and, for the first time, at group level. Numbers of activated (z-score>2.0) voxels were counted and their mean z-scores calculated in volumes of interest (occipital lobe (Nocc_lobe), segmented occipital gray-matter (NGM_occ_lobe), large veins (Nveins)), and in occipital-lobe voxels commonly activated in fQSM and fMRI component maps. Common but not entirely congruent regions of apparent activation were found in the occipital lobe in z-score maps from all modalities, fQSM, fMRI and PET, with distinct BOLD-negatively correlated regions in fQSM data. At subject-level, Nocc_lobe, NGM_occ_lobe and their mean z-scores were significantly smaller in fQSM than in fMRI, but their ratio, NGM_occ_lobe/Nocc_lobe, was comparable. Nveins did not statistically differ and the ratio Nveins/NGM_occ_lobe as well as the mean z-scores were higher for fQSM than for fMRI. In veins and immediate vicinity, z-score maps derived from both phase and fQSMdata showed positive and negative lobes resembling dipole shapes in simulated field and phase maps with no correlate in fMRI or PET data. Our results show that standard fMRI tools can directly be used for fQSM processing, and suggest that fQSM may have the potential to detect gray-matter activation distant from large veins, to improve detection of veins with stimulus-induced venous oxygen saturation (SvO2) variations, and to better localize areas of activation. However, our results seem to clearly expose issues that phenomenologically resemble an incomplete dipolar inversion and that need to be subject to further investigation. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. fMRI. In veins and immediate vicinity, z-score maps derived from both phase and fQSM-data showed positive and negative lobes resembling dipole shapes in simula...

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A Noninvasive Approach to Quantitative Functional Brain Mapping with H₂¹⁵O and Positron Emission Tomography

Cited by 226 publications

References 4 publications

Functional and cortical adaptations to central vision loss

Functional and cortical adaptations to central vision loss

Dopaminergic modulation of response inhibition: an fMRI study

Probing neuronal activation by functional quantitative susceptibility mapping under a visual paradigm: A group level comparison with BOLD fMRI and PET

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A Noninvasive Approach to Quantitative Functional Brain Mapping with H215O and Positron Emission Tomography

Cited by 226 publications

References 4 publications

Functional and cortical adaptations to central vision loss

Functional and cortical adaptations to central vision loss

Dopaminergic modulation of response inhibition: an fMRI study

Probing neuronal activation by functional quantitative susceptibility mapping under a visual paradigm: A group level comparison with BOLD fMRI and PET

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A Noninvasive Approach to Quantitative Functional Brain Mapping with H₂¹⁵O and Positron Emission Tomography