High-resolution fMRI of macaque V1

Goense, Jozien; Zappe, Anne-Catherin; Logothetis, Nikos K.

doi:10.1016/j.mri.2007.02.013

Cited by 65 publications

(59 citation statements)

References 36 publications

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“…In this case, though, such differences are minimized at the current spatial resolution (up to 2 mm) and the large smoothing kernel. Indeed, Goense et al [30,31] compared SE and GE and found that the lateral spread and extent of activation are usually similar. Finally, the major results for frontoparietal activations are similar for group maps based on all three or just the two animals scanned with the GE sequence.…”

Section: Resultsmentioning

confidence: 99%

Frontoparietal activity with minimal decision and control in the awake macaque at 7 T

Stoewer

Goense

et al. 2010

Magnetic Resonance Imaging

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Section: Resultsmentioning

confidence: 99%

Frontoparietal activity with minimal decision and control in the awake macaque at 7 T

Stoewer

Goense

et al. 2010

Magnetic Resonance Imaging

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“…Layer IVc of the macaque's primary visual cortex displays a vascular density that is ϳ30% higher than in the other layers (Weber et al, 2008). This vascularization difference results in discernability of layer IVc in highresolution SE BOLD fMRI (Goense et al, 2007). Zheng et al (1991) have estimated the difference in vascular density between blobs and interblobs in primate V1 to be 42%.…”

Section: Discussionmentioning

confidence: 99%

“…Our own recent study found a close correlation between vascularization and laminar organization of CO activity in V1 of macaques (Weber et al, 2008). Layer IVc, with the highest vascular density, was different from the other cortical layers by ϳ30%, rendering it clearly discernable in high-resolution spin-echo blood oxygenation level-dependent functional magnetic resonance imaging (SE BOLD fMRI) (Goense et al, 2007). Consequently, given the allegedly even higher blob/interblob difference found by Zheng and colleagues and a blob size of ϳ0.25 mm, blobs should be detectable using high-resolution MRI.…”

Section: Introductionmentioning

confidence: 94%

Vascularization of Cytochrome Oxidase-Rich Blobs in the Primary Visual Cortex of Squirrel and Macaque Monkeys

Keller¹,

Schüz²,

Logothetis³

et al. 2011

J. Neurosci.

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The close correlation between energy supply by blood vessels and energy consumption by cellular processes in the brain is the basis of blood flow-related functional imaging techniques. Regional differences in vascular density can be detected using high-resolution functional magnetic resonance imaging. Therefore, inhomogeneities in vascularization might help to identify anatomically distinct areas noninvasively in vivo. It was reported previously that cytochrome oxidase-rich blobs in the striate cortex of squirrel monkeys are characterized by a notably higher vascular density (42% higher than interblob regions). However, blobs have so far never been identified in vivo on the basis of their vascular density. Here, we analyzed blobs of the primary visual cortex of squirrel monkeys and macaques with respect to the relationship between vascularization and cytochrome oxidase activity. By double staining with cytochrome oxidase enzyme histochemistry to define the blobs and collagen type IV immunohistochemistry to quantify the blood vessels, a close correlation between oxidative metabolism and vascularization was confirmed and quantified in detail. The vascular length density in cytochrome oxidase blobs was on average 4.5% higher than in the interblob regions, a difference almost one order of magnitude smaller than previously reported. Thus, the vascular density that is closely associated with local average metabolic activity is a structural equivalent of cerebral metabolism and blood flow. However, the quantitative differences in vascularization between blob and interblob regions are small and below the detectability threshold of the noninvasive hemodynamic imaging methods of today.

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“…Based on similar cat visual stimulation studies, Harel et al found the highest CBV change at a small valley in the SE-BOLD cortical profile (which is consistent with our observation), but assigned the region with the highest SE-BOLD change to layer IV . Goense et al also reported that SE-BOLD peaked at the middle of the V1 cortex of monkey at 4.7 T (Goense and Logothetis, 2006), where the change in R 2 was found to be the highest after MION injection (Goense et al, 2007). A significant contribution of functional T 2 * change to SE-BOLD fMRI during a long readout time may shift the peak of the lamina response because the T 2 * contribution of pial veins monotonically decreases along cortical depth.…”

Section: Spatial Specificity Of Si-vaso Signalsmentioning

confidence: 95%

Improved cortical-layer specificity of vascular space occupancy fMRI with slab inversion relative to spin-echo BOLD at 9.4 T

Jin

Kim

2008

NeuroImage

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Cerebral blood volume (CBV)-weighted endogenous functional contrast can be obtained by the vascular space occupancy (VASO) technique. VASO relies on nonselective inversion for nulling blood signals, but the implementation of VASO at magnetic fields higher than 3 T is difficult due to similar T 1 values of tissue and blood water and a stronger counteracting blood oxygen leveldependent (BOLD) effect. To improve functional CBV sensitivity, we proposed to use VASO with slab-selective inversion (SI-VASO). Computer simulations showed that the SI-VASO approach significantly increases functional sensitivity compared to the original VASO in a stronger magnetic field with a shorter repetition time. To examine layer-dependent specificity, SI-VASO and spin-echo BOLD (SE-BOLD) functional magnetic resonance imaging (fMRI) experiments were performed on isoflurane-anesthetized cats during visual stimulation at 9.4 T. Unlike simultaneously acquired SE-BOLD signal, the SI-VASO signal peaked at 0.9 mm from the surface of the cortex and was localized to the middle cortical layer. The full-width at half maximal response across the cortex was narrower for SI-VASO than for SE-BOLD (1.7 mm vs. 2.5 mm, respectively), suggesting that SI-VASO is better localized to neuronally active sites than SE-BOLD fMRI. The magnitude of the SI-VASO change in the middle cortex was −1.45% with our experimental parameters, corresponding to a relative CBV change of ∼8% when baseline CBV was assumed to be 5% in a two-compartment model. The signal response profile across the cortex, the calculated CBV change, and the time course of SI-VASO fMRI were similar to those of previously obtained CBV-weighted fMRI with contrast agent in the same animal model, suggesting that SI-VASO measures predominately functional CBV responses.

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High-resolution fMRI of macaque V1

Cited by 65 publications

References 36 publications

Frontoparietal activity with minimal decision and control in the awake macaque at 7 T

Frontoparietal activity with minimal decision and control in the awake macaque at 7 T

Vascularization of Cytochrome Oxidase-Rich Blobs in the Primary Visual Cortex of Squirrel and Macaque Monkeys

Improved cortical-layer specificity of vascular space occupancy fMRI with slab inversion relative to spin-echo BOLD at 9.4 T

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