Cerebral blood volume sensitive layer-fMRI in the human auditory cortex at 7T: Challenges and capabilities

Faes, Lonike; Martino, Federico De; Huber, Laurentius

doi:10.1371/journal.pone.0280855

Cited by 11 publications

(4 citation statements)

References 89 publications

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“…However, it must be noted that the measures to reduce venous bias used in this study can only serve as a first order correction as the BOLD effect of large veins affects all depths of the parenchyma 77,78 and the convolutional effect of draining veins 79 cannot be accounted for with masking. Hence, other fMRI contrasts like SE-BOLD 80 or non-BOLD alternatives like VASO 12,15,81 are needed to be developed further to obtain laminar fMRI responses with an as low as possible effect of large vessels and our results can serve as a benchmark to compare these contrasts to.…”

Section: Discussionmentioning

confidence: 99%

Characterizing BOLD activation patterns in the human hippocampus with laminar fMRI

Pfaffenrot,

Bouyeure,

Gomes

et al. 2024

Preprint

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The human hippocampus has been extensively studied at the macroscale using functional magnetic resonance imaging (fMRI) but the underlying microcircuits at the mesoscale (i.e., at the level of layers) are largely uninvestigated in humans. We target two questions fundamental to hippocampal laminar fMRI: How does the venous bias affect the interpretation of hippocampal laminar responses? And can we establish a benchmark laminar fMRI experiment which robustly elicits single-subject hippocampal activation utilizing the most widely applied GRE-BOLD contrast? We comprehensively characterized GRE-BOLD responses as well as T2*, tSNR and physiological noise as a function of cortical depth in individual subfields of the human hippocampus. Our results show that the vascular architecture differs between subfields leading to subfield-specific laminar biases of GRE-BOLD responses. Using an autobiographical memory paradigm, we robustly acquired depth-specific BOLD responses in hippocampal subfields. In the CA1 subregion, our results indicate a more pronounced trisynaptic path input rather than dominant direct inputs from entorhinal cortex during autobiographical memory retrival. Our study provides unique insights into the hippocampus at the mesoscale level, and will help interpreting hippocampal laminar fMRI responses and allow researchers to test mechanistic hypotheses of hippocampal function.

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Section: Discussionmentioning

confidence: 99%

Characterizing BOLD activation patterns in the human hippocampus with laminar fMRI

Pfaffenrot,

Bouyeure,

Gomes

et al. 2024

Preprint

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“…We employed a 30 s on/off block design, which is used in many layer-fMRI studies, especially when also recording non-BOLD responses, because of a good tradeoff between detection sensitivity, temporal efficiency and signal integrity (e.g. Dresbach et al, 2023;Faes et al, 2023;Pizzuti et al, 2023). Given that the triphasic response observed here is clearly locked to the stimulus onset, we do not believe that the effect is driven by preceding stimuli.…”

Section: Limitations and Future Directionsmentioning

confidence: 99%

Laminar CBV and BOLD response-characteristics over time and space in the human primary somatosensory cortex at 7T

Dresbach,

Gulban,

Steinbach

et al. 2024

Preprint

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Uncovering the cortical representation of the body has been at the core of human brain mapping for decades, with special attention given to the digits. In the last decade, advances in functional magnetic resonance imaging (fMRI) technologies have opened the possibility of noninvasively unraveling the 3rd dimension of digit representations in humans along cortical layers. In laminar fMRI it is common to combine the use of the highly sensitive blood oxygen level dependent (BOLD) contrast with cerebral blood volume sensitive measurements, like vascular space occupancy (VASO), that are more specific to the underlying neuronal populations. However, the spatial and temporal VASO response characteristics across cortical depth to passive stimulation of the digits are still unknown. Therefore, we characterized haemodynamic responses to vibrotactile stimulation of individual digit-tips across cortical depth at 0.75 mm in-plane spatial resolution using BOLD and VASO fMRI at 7T. We could identify digit-specific regions of interest (ROIs) in putative Brodmann area 3b, following the known anatomical organization. In the ROIs, the BOLD response increased towards the cortical surface due to the draining vein effect, while the VASO response was more shifted towards middle cortical layers, likely reflecting bottom-up input from the thalamus, as expected. Interestingly, we also found slightly negative BOLD and VASO responses for non-preferred digits in the ROIs, potentially indicating neuronal surround inhibition. Finally, we explored the temporal signal dynamics for BOLD and VASO as a function of distance from activation peaks resulting from stimulation of contralateral digits. With this analysis, we showed a triphasic response consisting of an initial peak and a subsequent negative deflection during stimulation, followed by a positive post-stimulus response in BOLD and to some extent in VASO. While similar responses were reported with invasive methods in animal models, here we demonstrate a potential neuronal excitation-inhibition mechanism in a center-surround architecture across layers in the human somatosensory cortex. Given that, unlike in animals, human experiments do not rely on anesthesia and can readily implement extensive behavioral testing, obtaining this effect in humans is an important step towards further uncovering the functional significance of the different aspects of the triphasic response.

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“…These and other factors (e.g. the need for large field of views to image bilateral auditory cortical areas) make imaging auditory cortical regions sensitive to geometric distortions and signal dropouts due to large B 0 inhomogeneities (Moerel et al, 2021) and not only for BOLD type acquisitions (Faes et al, 2023). Furthermore, the percent signal change elicited in auditory regions is lower than in visual cortex (De Martino et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the effect of denoising submillimeter auditory fMRI data with NORDIC

Faes,

Lage-Castellanos,

Valente

et al. 2024

Preprint

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Functional magnetic resonance imaging (fMRI) has emerged as an essential tool for exploring human brain function. Submillimeter fMRI, in particular, has emerged as a tool to study mesoscopic computations. The inherently low signal to noise ratio (SNR) at submillimeter resolutions warrants the use of denoising approaches tailored at reducing thermal noise; the dominant contributing noise component in high resolution fMRI. NORDIC PCA is one of such approaches, and has been benchmarked against other approaches in several applications. Here, we investigate the effects that two versions of NORDIC denoising have on auditory submillimeter data. As investigating auditory functional responses poses unique challenges, we anticipated that the benefit of this technique would be especially pronounced. Our results show that NORDIC denoising improves the detection sensitivity and the reliability of estimates in submillimeter auditory fMRI data. These effects can be explained by the reduction of the noise-induced signal variability. However, we also observed a reduction in the average response amplitude (percent signal), which may suggest that a small amount of signal was also removed. We conclude that, while evaluating the effects of the signal reduction induced by NORDIC may be necessary for each application, using NORDIC in high resolution auditory fMRI studies may be advantageous because of the large reduction in variability of the estimated responses.

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Cerebral blood volume sensitive layer-fMRI in the human auditory cortex at 7T: Challenges and capabilities

Cited by 11 publications

References 89 publications

Characterizing BOLD activation patterns in the human hippocampus with laminar fMRI

Characterizing BOLD activation patterns in the human hippocampus with laminar fMRI

Laminar CBV and BOLD response-characteristics over time and space in the human primary somatosensory cortex at 7T

Evaluating the effect of denoising submillimeter auditory fMRI data with NORDIC

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