Lessons from fMRI about Mapping Cortical Columns

Kim, Seong‐Gi; Fukuda, Mitsuhiro

doi:10.1177/1073858407309541

Cited by 21 publications

(19 citation statements)

References 75 publications

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“…Thus, unlike the late positive deoxy-Hb-weighted OIS (Fig. 2) or the decomposed deoxy-Hb signal (Malonek and Grinvald, 1996), the BOLD fMRI signal evoked by horizontal grating is larger than that evoked by vertical grating in iso-orientation domains for the horizontal grating (Kim and Fukuda, 2008;Moon et al, 2007). Additionally, the increase in both plasma blood volume and total-Hb content in the same iso-orientation domains suggests that arterioles rather than capillaries should be responsible for the column-specific blood volume regulation because capillaries do not seem to dilate to sensory stimulation (Chaigneau et al, 2003;Kleinfeld et al, 1998;Takano et al, 2006).…”

Section: Spatial Specificity Of Fmrimentioning

confidence: 88%

Submillimeter-resolution fMRI

Fukuda

Poplawsky

Kim

2016

Progress in Brain Research

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Section: Spatial Specificity Of Fmrimentioning

confidence: 88%

Submillimeter-resolution fMRI

Fukuda

Poplawsky

Kim

2016

Progress in Brain Research

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“…Due to the indirect nature of the BOLD signal as a surrogate for neural activity, the spatial resolution of BOLD fMRI is a complex interplay between technical constraints (e.g., field strength, see Harel et al, 2006) that determine voxel size, physics (e.g., signal production as a function of sequence type and sensitivity to various vessel types and sizes, see Uludağ et al, 2009) and vascular point spread function (Menon and Goodyear, 1999;Sheth et al, 2004b;Harel et al, 2006;Shmuel et al, 2007;Yacoub et al, 2008;Kim and Fukuda, 2008). Thus, as pointed out by Harrison et al, 2002, further detailed mapping studies of blood pathways and associated control points are needed to estimate the ultimate spatial resolution of hemodynamic-based functional imaging methods such as fMRI.…”

Section: Hemodynamic Variations Induced By Local Vasodilationsmentioning

confidence: 99%

Simulation study of brain blood flow regulation by intra-cortical arterioles in an anatomically accurate large human vascular network. Part II: Flow variations induced by global or localized modifications of arteriolar diameters

Lorthois¹,

Cassot²,

Lauwers³

2011

NeuroImage

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. In a companion paper (Lorthois et al., Neuroimage, in press), we perform the first simulations of blood flow in an anatomically accurate large human intra-cortical vascular network (~10000 segments), using a 1D non-linear model taking into account the complex rheological properties of blood flow in microcirculation. This model predicts blood pressure, blood flow and hematocrit distributions, volumes of functional vascular territories, regional flow at voxel and network scales, etc. Using the same approach, we study flow reorganizations induced by global arteriolar vasodilations (an isometabolic global increase in cerebral blood flow). For small to moderate global vasodilations, the relationship between changes in volume and changes in flow is in close agreement with Grubb's law, providing a quantitative tool for studying the variations of its exponent with underlying vascular architecture. A significant correlation between blood flow and vascular structure at the voxel scale, practically unchanged with respect to baseline, is demonstrated. Furthermore, the effects of localized arteriolar vasodilations, representative of a local increase in metabolic demand, are analyzed. In particular, localized vasodilations induce flow changes, including vascular steal, in the neighboring arteriolar trunks at small distances (b 300 μm), while their influence in the neighboring veins is much larger (about 1 mm), which provides an estimate of the vascular point spread function. More generally, for the first time, the hemodynamic component of various functional neuroimaging techniques has been isolated from metabolic and neuronal components, and a direct relationship with several known characteristics of the BOLD signal has been demonstrated. IntroductionThere is increasing recognition that, by its structural implication in neuro-vascular coupling, underlying vascular architecture is a key player in hemodynamically based functional imaging techniques (including fMRI and PET) (Harrison et al., 2002;d'Esposito et al., 2003;Logothetis and Wandell, 2004;Lauwers et al., 2008;Weber et al., 2008). In particular, the spatial resolution and specificity of such techniques are bound to the density of blood capillary vasculature and blood flow regulating structures (Harel et al., 2006). This is especially important in the context of high field fMRI Harel et al., 2006), because, despite a dramatic increase in the theoretical spatial resolution obtained by using higher magnetic fields, associated with other hardware advancements, "the spatial extent of the hemodynamic response ultimately will impose a fundamental limitation on the spatial resolution of fMRI modalities" ).However, little is known about the fundamentals of the relationship between vascular structure and hemodynamic changes induced by brain activation. A growing body of evidence indicates that neurons, glia, and cerebral blood vessels, actin...

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“…An fMRI study of the visual cortex demonstrated that accurate localization and resolution of the cortical columns could only be achieved when visual stimuli were kept relatively short [17]. In addition, other studies have suggested that appropriate task paradigms and activity quantification methods are required in order to evaluate the spatial resolution limits of BOLD fMRI [18,19].…”

Section: Introductionmentioning

confidence: 99%