Cortical layer-dependent BOLD and CBV responses measured by spin-echo and gradient-echo fMRI: Insights into hemodynamic regulation

Zhao, Fuqiang; Wang, Ping; Hendrich, Kristy; Uğurbil, Kâmil; Kim, Seong Gi

doi:10.1016/j.neuroimage.2005.11.013

Cited by 257 publications

(308 citation statements)

References 49 publications

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“…In order to estimate the relative CBV change from the VASO signal change, a value of CBV rest needs to be assumed (usually 5.5%) . Although microvascular CBV rest is relatively homogeneously distributed across layers (Kim et al, 2013;Weber et al, 2008), when macrovasculature is also included the total CBV rest was found to be largest at the cortical surface, decreasing with cortical depth (Kennerley et al, 2005;Zhao et al, 2006). Higher CBV rest at the cortical surface is associated with a smaller relative ΔCBV for the same VASO signal change.…”

Section: Discussionmentioning

confidence: 91%

“…4D in (Kennerley et al, 2005) and Fig. 3A in (Zhao et al, 2006), respectively). When laminarindependent homogeneous baseline CBV is assumed, the baseline CBV in surface voxels is underestimated and thus, the relative CBV change calculated from VASO signal change is overestimated.…”

Section: Figmentioning

confidence: 84%

“…This resolution is thus insufficient to resolve laminar features, but adequate to estimate the influence of surface vasculature. Considering the laminar dependence of total CBV at rest, surface voxels are assumed to have 12% higher baseline CBV than deeper layers (Kennerley et al, 2005;Zhao et al, 2006) (see also discussion and Fig. 3D).…”

Section: Surface Detectionmentioning

confidence: 99%

“…Based on the ratio of the voxel size and cortical thickness, 12% higher CBV rest is assumed in surface voxels (e.g. surface/deeper CBV ratio of ≈ 0.56/0.44 (Kennerley et al, 2005), or ≈ 0.57/0.43 (Zhao et al, 2006)). These ratios are estimated based on the published profiles ( Fig.…”

Section: Figmentioning

confidence: 99%

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Investigation of the neurovascular coupling in positive and negative BOLD responses in human brain at 7T

et al. 2014

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Section: Discussionmentioning

confidence: 91%

Section: Figmentioning

confidence: 84%

Section: Surface Detectionmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of the neurovascular coupling in positive and negative BOLD responses in human brain at 7T

et al. 2014

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“…The sensitivity gain of the CBV measurement over the BOLD technique is dependent on the dose of the contrast agent, the imaging parameters, and the magnetic field. When 5-15 mg iron/kg body weight is used, the sensitivity gain is about 1.3 to 5-fold (Mandeville et al, 1998;Mandeville et al, 2001;Kim and Ugurbil, 2003;Zhao et al, 2006).…”

Section: Sensitivity and Specificity Of Hemodynamic-based Fmrimentioning

confidence: 99%

Lessons from fMRI about Mapping Cortical Columns

Kim

Fukuda

2007

Neuroscientist

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Recently-developed functional magnetic resonance imaging (fMRI) can map small functional structures non-invasively and repeatedly without any depth limitation. However, there has been a persistent concern as to whether the high-resolution fMRI signals actually mark the sites of increased neural activity. To examine this outstanding issue, we used iso-orientation columns of isofluraneanestheized cats as a biological model and confirmed the neural correlation of fMRI iso-orientation maps by comparing with intrinsic optical imaging maps. Our results suggest that highest fMRI signals indeed indicate the sites of increased neuronal activity. Now fMRI can be used to determine plastic and/or developmental change of functional columnar structure possibly on a layer to layer basis. In this review we focus mainly on what technical aspects should be considered when mapping functional cortical columns, including imaging techniques and experimental design.

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Layer‐specific BOLD activation in human V1

Koopmans¹,

Barth²,

Norris³

2010

Human Brain Mapping

216

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The neocortex is known to have a distinct laminar structure which has previously been probed in animals using high-resolution fMRI. Detection of layer-specific activation in humans has however to date proven elusive. In this study we demonstrate for the first time such layer-specific activation, specifically at a depth corresponding to layer IV of human primary visual cortex (V1). We used a gradient-echo (GE) sequence at 3T with an isotropic resolution of 0.75 mm, in which a stria at the depth of layer IV was visible in the averaged time series, and could be used as an anatomical landmark. Upon visual stimulation (7.5 Hz flickering checkerboard) the signal increase of 3% in layer IV was significantly higher than in the neighboring laminae. The width of this activation peak was 0.8-1 mm. Based on this result and known laminar organization of the intracortical vasculature we conclude that in the direction perpendicular to the cortical surface the intrinsic spatial resolution of the GE-BOLD fMRI signal is in the submillimetre range. Human laminar fMRI is a significant development which may improve our understanding of intracortical activation patterns and of the way in which different cortical regions interact.

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Cortical layer-dependent BOLD and CBV responses measured by spin-echo and gradient-echo fMRI: Insights into hemodynamic regulation

Cited by 257 publications

References 49 publications

Investigation of the neurovascular coupling in positive and negative BOLD responses in human brain at 7T

Investigation of the neurovascular coupling in positive and negative BOLD responses in human brain at 7T

Lessons from fMRI about Mapping Cortical Columns

Layer‐specific BOLD activation in human V1

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