A critical assessment of data quality and venous effects in sub-millimeter fMRI

Kay, Kendrick; Jamison, Keith; Vizioli, Luca; Zhang, Ruyuan; Margalit, Eshed; Uğurbil, Kâmil

doi:10.1016/j.neuroimage.2019.02.006

Cited by 100 publications

(168 citation statements)

References 103 publications

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“…(Kashyap et al, 2018)). This can result in additional fMRI signal changes in the GM voxels in close proximity to PVs (see, for example, recent reports of (Kay et al, 2019;Moerel et al, 2018)). Although we model dHb and CBV changes in extra-and intra-vascular compartments of PVs, the contribution of the blooming effect to the laminar BOLD signal is not accounted for in the proposed model.…”

Section: Limitations and Future Prospectsmentioning

confidence: 99%

A dynamical model of the laminar BOLD response

Havlíček

Uludağ

2019

Preprint

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High-resolution functional magnetic resonance imaging (fMRI) using blood oxygenation dependent level-dependent (BOLD) signal is an increasingly popular tool to non-invasively examine neuronal processes at the mesoscopic level. However, as the BOLD signal stems from hemodynamic changes, its temporal and spatial properties do not match those of the underlying neuronal activity. In particular, the laminar BOLD response (LBR), commonly measured with gradient-echo (GE) MRI sequence, is confounded by non-local changes in deoxygenated hemoglobin and cerebral blood volume propagated within intracortical ascending veins, leading to a unidirectional blurring of the neuronal activity distribution towards the cortical surface. Here, we present a new cortical depth-dependent model of the BOLD response based on the principle of mass conservation, which takes the effect of ascending (and pial) veins on the cortical BOLD responses explicitly into account. It can be used to dynamically model cortical depth profiles of the BOLD signal as a function of various baselineand activity-related physiological parameters for any spatiotemporal distribution of neuronal changes. We demonstrate that the commonly observed spatial increase of LBR is mainly due to baseline blood volume increase towards the surface. In contrast, an occasionally observed local maximum in the LBR (i.e. the so-called "bump") is mainly due to spatially inhomogeneous neuronal changes rather than locally higher baseline blood volume. In addition, we show that the GE-BOLD signal laminar point-spread functions, representing the signal leakage towards the surface, depend on several physiological parameters and on the level of neuronal activity. Furthermore, even in the case of simultaneous neuronal changes at each depth, inter-laminar delays of LBR transients are present due to the ascending vein. In summary, the model provides a conceptual framework for the biophysical interpretation of common experimental observations in high-resolution fMRI data. In the future, the model will allow for deconvolution of the spatiotemporal hemodynamic bias of the LBR and provide an estimate of the underlying laminar excitatory and inhibitory neuronal activity.

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Section: Limitations and Future Prospectsmentioning

confidence: 99%

A dynamical model of the laminar BOLD response

Havlíček

Uludağ

2019

Preprint

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“…Finally, despite the advances afforded by UHF imaging, GE-EPI remains limited by vasculature contribution to BOLD signals at the cortical surface resulting in loss of spatial 34 specificity (Kay et al, 2019). Here, we combined several approaches to reduce this superficial bias by removing voxels with high temporal signal to noise ratio (Olman et al, 2007) and high t-statistic for stimulation contrast (Kashyap et al, 2018;Polimeni et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Fine-scale computations for adaptive processing in the human brain

Zamboni

Kemper

Goncalves

et al. 2020

Preprint

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Humans and animals are known to adapt to the statistics of the environment by reducing brain responses to repetitive sensory information. Despite the importance of this rapid form of brain plasticity for efficient information processing, the fine-scale circuits that support this adaptive processing in the human brain remain largely unknown. Here, we capitalize on the submillimetre resolution afforded by ultra-high field (UHF) imaging to examine BOLD-fMRI signals across cortical depth and discern competing hypotheses about the brain mechanisms (feedforward vs. feedback) that mediate visual adaptation. Combining UHF imaging with a visual adaptation paradigm comprising repeated presentation of gratings at the same orientation, we provide evidence for the fine-scale human brain circuits that mediate adaptive visual processing. We demonstrate that visual adaptation is implemented by suppressive local recurrent processing within visual cortex, as indicated by stronger BOLD decrease in superficial than middle and deeper layers. Further, functional connectivity analysis shows dissociable connectivity mechanisms for adaptive processing: feedforward connectivity within the visual cortex, while feedback connectivity from posterior parietal to visual cortex, reflecting top-down influences (i.e. expectation for repeated stimuli) on visual processing. Thus, our findings provide evidence for a circuit of local recurrent and feedback interactions that mediate rapid brain plasticity for adaptive information processing.

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“…Three approaches were combined to reduce the influence from large pial veins. First, vertices with low EPI intensity from the mean EPI image were removed (Kay, Jamison et al 2019) . The mean EPI image was first bias-corrected to remove non-uniformity of signal intensity (3dUnifize in AFNI), then vertices with an intensity below 75% of the mean intensity of all surface vertices were excluded.…”

Section: Roi Definitionmentioning

confidence: 99%

Layer-dependent multiplicative effects of spatial attention on contrast responses in human early visual cortex

Guo

Liu

Cui

et al. 2020

Preprint

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Attention mechanisms at different cortical layers of human visual cortex remain poorly understood. Using submillimeter-resolution fMRI at 7T, we investigated the effects of top-down spatial attention on the contrast responses across different cortical depths in human early visual cortex. Gradient echo (GE) T2* weighted BOLD signal showed an additive effect of attention on contrast responses across cortical depths. Compared to the middle cortical depth, attention modulation was stronger in the superficial and deep depths of V1, and also stronger in the superficial depth of V2 and V3. Using ultra-high resolution (0.3mm in-plane) balanced steadystate free precession (bSSFP) fMRI, a multiplicative scaling effect of attention was found in the superficial and deep layers, but not in the middle layer of V1. Attention modulation of low Highlights • Response or activity gain of spatial attention in superficial and deep layers • Contrast gain or baseline shift of attention in V1 middle layer • Nonlinearity of large blood vessel causes additive effect of attention on T2* BOLD

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A critical assessment of data quality and venous effects in sub-millimeter fMRI

Cited by 100 publications

References 103 publications

A dynamical model of the laminar BOLD response

A dynamical model of the laminar BOLD response

Fine-scale computations for adaptive processing in the human brain

Layer-dependent multiplicative effects of spatial attention on contrast responses in human early visual cortex

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