Submillimeter-resolution fMRI

Fukuda, Mitsuhiro; Poplawsky, Alexander John; Kim, S.-G.

doi:10.1016/bs.pbr.2016.03.003

Cited by 14 publications

(9 citation statements)

References 140 publications

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“…Activity patterns obtained in our experiments are similar to the blood oxygenation level dependent signals (BOLD) produced in fMRI or activity patterns obtained by near-infrared spectroscopy (NIRS) (Fukuda et al, 2016; Lenkov et al, 2012). Both BOLD fMRI and NIRS methods employ hemoglobin as an endogenous contrast agent and visualize neuronal activity indirectly via correlations with local metabolism (Arthurs and Boniface, 2002).…”

Section: Introductionsupporting

confidence: 82%

Planar implantable sensor for in vivo measurement of cellular oxygen metabolism in brain tissue

Tsytsarev

Akkentli

Pumbo

et al. 2017

Journal of Neuroscience Methods

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Background Brain imaging methods are continually improving. Imaging of the cerebral cortex is widely used in both animal experiments and charting human brain function in health and disease. Among the animal models, the rodent cerebral cortex has been widely used because of patterned neural representation of the whiskers on the snout and relative ease of activating cortical tissue with whisker stimulation. New Method We tested a new planar solid-state oxygen sensor comprising a polymeric film with a phosphorescent oxygen-sensitive coating on the working side, to monitor dynamics of oxygen metabolism in the cerebral cortex following sensory stimulation. Results Sensory stimulation led to changes in oxygenation and deoxygenation processes of activated areas in the barrel cortex. We demonstrate the possibility of dynamic mapping of relative changes in oxygenation in live mouse brain tissue with such a sensor. Comparison with Existing Method Oxygenation-based functional magnetic resonance imaging (fMRI) is very effective method for functional brain mapping but have high costs and limited spatial resolution. Optical imaging of intrinsic signal (IOS) does not provide the required sensitivity, and voltage-sensitive dye optical imaging (VSDi) has limited applicability due to significant toxicity of the voltage-sensitive dye. Our planar solid-state oxygen sensor imaging approach circumvents these limitations, providing a simple optical contrast agent with low toxicity and rapid application. Conclusions The planar solid-state oxygen sensor described here can be used as a tool in visualization and real-time analysis of sensory-evoked neural activity in vivo. Further, this approach allows visualization of local neural activity with high temporal and spatial resolution.

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Section: Introductionsupporting

confidence: 82%

Planar implantable sensor for in vivo measurement of cellular oxygen metabolism in brain tissue

Tsytsarev

Akkentli

Pumbo

et al. 2017

Journal of Neuroscience Methods

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“…The blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) has proven to be a valuable tool to non-invasively probe various brain areas at a macroscopic scale (Fukuda et al, 2016; Goense et al, 2016). With continued improvement in both spatial and temporal resolution of MRI, BOLD fMRI has recently been applied to study the temporal dynamics of the laminar hemodynamic response and its underlying neural activity in both animal models and humans (Hirano et al, 2011; Jin and Kim, 2008; Siero et al, 2011; Silva and Koretsky, 2002).…”

Section: Introductionmentioning

confidence: 99%

Investigating the spatiotemporal characteristics of the deoxyhemoglobin-related and deoxyhemoglobin-unrelated functional hemodynamic response across cortical layers in awake marmosets

2018

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Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) has become a major tool to map neural activity. However, the spatiotemporal characteristics of the BOLD functional hemodynamic response across the cortical layers remain poorly understood. While human fMRI studies suffer from low spatiotemporal resolution, the use of anesthesia in animal models introduces confounding factors. Additionally, inflow contributions to the fMRI signal become non-negligible when short repetition times (TRs) are used. In the present work, we mapped the BOLD fMRI response to somatosensory stimulation in awake marmosets. To address the above technical concerns, we used a dual-echo gradient-recalled echo planar imaging (GR-EPI) sequence to separate the deoxyhemoglobin-related response (absolute T* differences) from the deoxyhemoglobin-unrelated response (relative S changes). We employed a spatial saturation pulse to saturate incoming arterial spins and reduce inflow effects. Functional GR-EPI images were obtained from a single coronal slice with two different echo times (13.5 and 40.5ms) and TR=0.2s. BOLD, T*, and S images were calculated and their functional responses were detected in both hemispheres of primary somatosensory cortex, from which five laminar regions (L1+2, L3, L4, L5, and L6) were derived. The spatiotemporal distribution of the BOLD response across the cortical layers was heterogeneous, with the middle layers having the highest BOLD amplitudes and shortest onset times. ΔT* also showed a similar trend. However, functional S changes were detected only in L1+2, with a fast onset time. Because inflow effects were minimized, the source of S functional changes in L1+2 could be attributed to a reduction of cerebrospinal fluid volume fraction due to the functional increase in cerebral blood volume and to unmodeled T* changes in the extra- and intra-venous compartments. Caution should be exercised when interpreting laminar BOLD fMRI changes in superficial layers as surrogates of underlying neural activity.

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“…Red and blue traces: OIS evoked by horizontal and vertical gratings, respectively; green traces: differential profile (red − blue); horizontal grey bars: horizontal iso-orientation domains determined by negative deflections of green traces at 1.5 s in deoxyHb-weighted OISI. Adapted from [17].…”

Section: Spatial Specificity Of Fmri Examined With the Functional Colmentioning

confidence: 99%

Time-dependent spatial specificity of high-resolution fMRI: insights into mesoscopic neurovascular coupling

Fukuda

Poplawsky

Kim

2020

Phil. Trans. R. Soc. B

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High-resolution functional magnetic resonance imaging (fMRI) is becoming increasingly popular because of the growing availability of ultra-high magnetic fields which are capable of improving sensitivity and spatial resolution. However, it is debatable whether increased spatial resolutions for haemodynamic-based techniques, like fMRI, can accurately detect the true location of neuronal activity. We have addressed this issue in functional columns and layers of animals with haemoglobin-based optical imaging and different fMRI contrasts, such as blood oxygenation level-dependent, cerebral blood flow and cerebral blood volume fMRI. In this review, we describe empirical evidence primarily from our own studies on how well these fMRI signals are spatially specific to the neuronally active site and discuss insights into neurovascular coupling at the mesoscale. This article is part of the theme issue ‘Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity’.

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Submillimeter-resolution fMRI

Cited by 14 publications

References 140 publications

Planar implantable sensor for in vivo measurement of cellular oxygen metabolism in brain tissue

Planar implantable sensor for in vivo measurement of cellular oxygen metabolism in brain tissue

Investigating the spatiotemporal characteristics of the deoxyhemoglobin-related and deoxyhemoglobin-unrelated functional hemodynamic response across cortical layers in awake marmosets

Time-dependent spatial specificity of high-resolution fMRI: insights into mesoscopic neurovascular coupling

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