Task-Evoked BOLD Responses Are Normal in Areas of Diaschisis After Stroke

Fair, Damien A.; Snyder, Abraham Z.; Connor, Lisa Tabor; Nardos, Binyam; Corbetta, Maurizio

doi:10.1177/1545968308317699

Cited by 11 publications

(10 citation statements)

References 20 publications

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“…Consequently, these changes may have only a minimal effect on the signal. This conclusion is further supported by literature suggesting that altered HDRs are not observed in diaschesis [19], which is a condition characterized by loss of function in a portion of the brain that is distant from the lesion.…”

Section: Discussionsupporting

confidence: 82%

Changes in hemodynamic responses in chronic stroke survivors do not affect fMRI signal detection in a block experimental design

Promjunyakul

Schmit

Schindler-Ivens

2013

Magnetic Resonance Imaging

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The use of canonical functions to model BOLD-fMRI data in people post-stroke may lead to inaccurate descriptions of task-related brain activity. The purpose of this study was to determine whether the spatiotemporal profile of hemodynamic responses (HDRs) obtained from stroke survivors during an event-related experiment could be used to develop individualized HDR functions that would enhance BOLD-fMRI signal detection in block experiments. Our long term goal was to use this information to develop individualized HDR functions for stroke survivors that could be used to analyze brain activity associated with locomotor-like movements. We also aimed to examine the reproducibility of HDRs obtained across two scan sessions in order to determine whether data from a single event-related session could be used to analyze block data obtained in subsequent sessions. Results indicate that the spatiotemporal profile of HDRs measured with BOLD-fMRI in stroke survivors was not the same as that observed in individuals without stroke. We observed small between-group differences in the rates of rise and decline of HDRs that were more apparent in individuals with cortical as compared to subcortical stroke. There were no differences in the peak or time to peak of HDRs in people with and without stroke. Of interest, differences in HDRs were not as substantial as expected from previous reports and were not large enough to necessitate the use of individualized HDR functions to obtain valid measures of movement-related brain activity. We conclude that all strokes do not affect the spatiotemporal characteristics of HDRs in such a way as to produce inaccurate representations of brain activity as measured by BOLD-fMRI. However, care should be taken to identify individuals whose BOLD-fMRI data may not provide an accurate representation of underlying brain activation when canonical models are used. Examination of HDRs need not be done for each scan session, as our data suggest that the characteristics of HDRs in stroke survivors are reproducible across days.

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Section: Discussionsupporting

confidence: 82%

Changes in hemodynamic responses in chronic stroke survivors do not affect fMRI signal detection in a block experimental design

Promjunyakul

Schmit

Schindler-Ivens

2013

Magnetic Resonance Imaging

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“…The BOLD responses were minimally affected in areas of chronic diaschisis. For the patients in this study, the mechanism underlying the BOLD signal, which includes a mismatch between neuronally driven increases in blood flow and a corresponding increase in oxygen use, appeared to be intact in areas of chronic diaschisis (Fair et al, 2009). …”

Section: Participant Variables: Inclusion and Exclusion Criteriamentioning

confidence: 74%

Neuroimaging in aphasia treatment research: Quantifying brain lesions after stroke

et al. 2013

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New structural and functional neuroimaging methods continue to rapidly develop, offering promising tools for cognitive neuroscientists. In the last 20 years, advanced magnetic resonance imaging (MRI) techniques have provided invaluable insights into how language is represented and processed in the brain and how it can be disrupted by damage to, or dysfunction of, various parts of the brain. Current functional MRI (fMRI) approaches have also allowed researchers to purposefully investigate how individuals recover language after stroke. This paper presents recommendations for quantification of brain lesions derived from discussions among international researchers at the Neuroimaging in Aphasia Treatment Research Workshop held at Northwestern University (Evanston, Illinois, USA). Methods for detailing and characterizing the brain damage that can influence results of fMRI studies in chronic aphasic stroke patients are discussed. Moreover, we aimed to provide the reader with a set of general practical guidelines and references to facilitate choosing adequate structural imaging strategies that facilitate fMRI studies in aphasia treatment research.

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“…Some investigators have demonstrated significant reductions in resting activity in structurally intact regions homologous to the site of damage using positron emission tomography (24) and magnetoencephalography (25), as well as decreases in EEG coherence throughout the lesion hemisphere (26) and across the entire brain (27). One study, however, found that whereas resting PET activity showed significant decreases at a distance from the lesioned site, task-evoked BOLD signal was minimally affected (24).…”

Section: Discussionmentioning

confidence: 98%

Double dissociation of two cognitive control networks in patients with focal brain lesions

Nomura

Gratton

Visser

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

168

155

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Neuroimaging studies of cognitive control have identified two distinct networks with dissociable resting state connectivity patterns. This study, in patients with heterogeneous damage to these networks, demonstrates network independence through a double dissociation of lesion location on two different measures of network integrity: functional correlations among network nodes and within-node graph theory network properties. The degree of network damage correlates with a decrease in functional connectivity within that network while sparing the nonlesioned network. Graph theory properties of intact nodes within the damaged network show evidence of dysfunction compared with the undamaged network. The effect of anatomical damage thus extends beyond the lesioned area, but remains within the bounds of the existing network connections. Together this evidence suggests that networks defined by their role in cognitive control processes exhibit independence in resting data.functional MRI | functional connectivity | graph theory | resting state | stroke C ognitive control is required in everyday life to coordinate our thoughts and actions to achieve internal goals while still allowing the flexibility to adjust these goals with changing task demands. Although previous studies have attributed cognitive control to various prefrontal cortical regions (1, 2), recently it has been proposed that a dual-network architecture exists in the human brain in which cognitive control depends on regions that extend beyond the frontal cortex (3). In a recent cross-task analysis, Dosenbach et al. (4) identified a number of regions active during different stages of cognitive control tasks. Given the difficulty in isolating cognitive control networks that are simultaneously active during task performance, the investigators took advantage of the recent advent of resting state functional MRI (rs-fMRI) for detecting spontaneous fluctuations between coherent brain regions. In a follow-up study, these predefined regions of interest (ROIs) obtained from the task data served as seeds in a correlation analysis of rs-fMRI data (3) in which graph theory and hierarchical clustering were applied to the correlation matrices. These analyses identified two distinct networks labeled as fronto-parietal (FP) and cinguloopercular (CO) (Fig. 1A). Based on their role in cognitive tasks, the FP network consists of nodes proposed to provide signals that act on a rapid time scale to initiate and adjust control, whereas the CO network nodes act to provide signals that allow set maintenance over a longer time scale (3,5).Numerous studies using rs-fMRI have shown that neuronal activity is characterized by temporal correlations in blood oxygen level-dependent signal across disparate brain regions (6, 7). These fluctuations seem highly consistent over time and reflect the presence of intrinsic functional (8) and structural (9) connectivity. Among these fluctuations, different networks can be distinguished, many of which show remarkable resemblance to task-related networks (...

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Task-Evoked BOLD Responses Are Normal in Areas of Diaschisis After Stroke

Cited by 11 publications

References 20 publications

Changes in hemodynamic responses in chronic stroke survivors do not affect fMRI signal detection in a block experimental design

Changes in hemodynamic responses in chronic stroke survivors do not affect fMRI signal detection in a block experimental design

Neuroimaging in aphasia treatment research: Quantifying brain lesions after stroke

Double dissociation of two cognitive control networks in patients with focal brain lesions

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