Rapid BOLD fMRI signal loss in the primary motor cortex of a stroke patient

Carvalho, Sonia M. Fioravanti; Pontes-Neto, Octávio M.; Fábio, Soraia Ramos Cabette; Leite, João P.; Santos, Antônio Carlos dos; Araújo, Dráulio Barros de

doi:10.1590/s0004-282x2008000600022

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…Herein, a remarkable and consistent rapid decrease of the BOLD signal amplitude was detected during a single fMRI session in all studied patients. A similar finding has been reported by our group in a single stroke patient study8.…”

Section: Discussionsupporting

confidence: 92%

“…The key finding of this work is the remarkable progressive attenuation of the BOLD response when stroke survivors were moving their paretic hand8. Such short-term BOLD attenuation was consistently observed in every single patient in the present study, and led to a siginificant underestimation of the region of activation when the conventional GLM analysis was applied to the data.…”

Section: Discussionsupporting

confidence: 63%

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The Stability of the Blood Oxygenation Level-Dependent Functional MRI Response to Motor Tasks Is Altered in Patients With Chronic Ischemic Stroke

Mazzetto-Betti

Leoni

Pontes-Neto

et al. 2010

Stroke

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Background and Purpose-Functional MRI is a powerful tool to investigate recovery of brain function in patients withstroke. An inherent assumption in functional MRI data analysis is that the blood oxygenation level-dependent (BOLD) signal is stable over the course of the examination. In this study, we evaluated the validity of such assumption in patients with chronic stroke. Methods-Fifteen patients performed a simple motor task with repeated epochs using the paretic and the unaffected hand in separate runs. The corresponding BOLD signal time courses were extracted from the primary and supplementary motor areas of both hemispheres. Statistical maps were obtained by the conventional General Linear Model and by a parametric General Linear Model. Results-Stable BOLD amplitude was observed when the task was executed with the unaffected hand. Conversely, the BOLD signal amplitude in both primary and supplementary motor areas was progressively attenuated in every patient when the task was executed with the paretic hand. The conventional General Linear Model analysis failed to detect brain activation during movement of the paretic hand. However, the proposed parametric General Linear Model corrected the misdetection problem and showed robust activation in both primary and supplementary motor areas. Conclusions-The

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 63%

The Stability of the Blood Oxygenation Level-Dependent Functional MRI Response to Motor Tasks Is Altered in Patients With Chronic Ischemic Stroke

Mazzetto-Betti

Leoni

Pontes-Neto

et al. 2010

Stroke

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“…However, it is important to point out some limitations and caveats of our study: (i) the absence of a control group (without intervention), which limits our ability to associate the observed changes to the MT intervention; (ii) the number of patients is small; (iii) we did not evaluate patient's clinical improvement; (iv) the cohort was restricted to well-recovered patients, with mild motor impairment, as study participants should be able to move their hand during the fMRI protocol; (v) the use of fixedeffects models, which limits the conclusion of our results to the population studied; (vi) it is know that within-session fMRI reliability is higher than between-session, particularly in stroke survivors who show altered cerebrovascular coupling, which may interfere with fMRI analysis and interpretation 26,47,48 ;…”

Section: Discussionmentioning

confidence: 99%

Neurofunctional changes after a single mirror therapy intervention in chronic ischemic stroke

Novaes

Palhano-Fontes

Peres

et al. 2018

International Journal of Neuroscience

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“…Low SNR [Bonakdarpour et al, 2007;Krainik et al, 2005;Murata et al, 2006] and progressive attenuation of the magnitude of BOLD response [Carvalho et al, 2008;Mazzetto-Betti et al, 2010] may lead to underestimation of neural activity in patients after stroke. As previously discussed, low SNR is already a problem in the detection of neural activity in aging populations [Brodtmann et al, 2003;D'Esposito et al, 1999;Huettel et al, 2001], and this may be compounded in older stroke patients.…”

Section: Low Snrmentioning

confidence: 99%

Beyond BOLD: Optimizing functional imaging in stroke populations

Veldsman

Cumming

Brodtmann

2014

Human Brain Mapping

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Blood oxygenation level-dependent (BOLD) signal changes are often assumed to directly reflect neural activity changes. Yet the real relationship is indirect, reliant on numerous assumptions, and subject to several sources of noise. Deviations from the core assumptions of BOLD contrast functional magnetic resonance imaging (fMRI), and their implications, have been well characterized in healthy populations, but are frequently neglected in stroke populations. In addition to conspicuous local structural and vascular changes after stroke, there are many less obvious challenges in the imaging of stroke populations. Perilesional ischemic changes, remodeling in regions distant to lesion sites, and diffuse perfusion changes all complicate interpretation of BOLD signal changes in standard fMRI protocols. Most stroke patients are also older than the young populations on which assumptions of neurovascular coupling and the typical analysis pipelines are based. We present a review of the evidence to show that the basic assumption of neurovascular coupling on which BOLD-fMRI relies does not capture the complex changes arising from stroke, both pathological and recovery related. As a result, estimating neural activity using the canonical hemodynamic response function is inappropriate in a number of contexts. We review methods designed to better estimate neural activity in stroke populations. One promising alternative to event-related fMRI is a resting-state-derived functional connectivity approach. Resting-state fMRI is well suited to stroke populations because it makes no performance demands on patients and is capable of revealing network-based pathology beyond the lesion site.

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Rapid BOLD fMRI signal loss in the primary motor cortex of a stroke patient

Cited by 5 publications

References 10 publications

The Stability of the Blood Oxygenation Level-Dependent Functional MRI Response to Motor Tasks Is Altered in Patients With Chronic Ischemic Stroke

The Stability of the Blood Oxygenation Level-Dependent Functional MRI Response to Motor Tasks Is Altered in Patients With Chronic Ischemic Stroke

Neurofunctional changes after a single mirror therapy intervention in chronic ischemic stroke

Beyond BOLD: Optimizing functional imaging in stroke populations

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