Layer-fMRI VASO with short stimuli and event-related designs at 7 T

Dresbach, Sebastian; Huber, Laurentius; Gulban, Omer Faruk; Goebel, Rainer

doi:10.1016/j.neuroimage.2023.120293

Cited by 8 publications

(12 citation statements)

References 58 publications

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“…This can be explained by the higher noise level in superficial layers which downscales the response at the cortical surface when interpreting the data in terms of z-scores (for z-scored event-related averages, see Supplementary Figures S8-S10 ). These findings are in line with our previous VASO results comparing block-to event-wise stimulation in humans (Dresbach et al, 2023) and animal work using MION contrast agent (e.g. Jin and Kim, 2008).…”

Section: Discussionsupporting

confidence: 92%

“…Firstly, having 4 equally spaced blocks within the acquisition period allowed us to systematically jitter the onset of our stimuli, thereby sampling the haemodynamic response to our stimuli with an effective sampling rate of 785 ms, uncoupling pair TR and effective temporal resolution. Secondly, including the delay before the BOLD EPI acquisition increased the temporal SNR (tSNR) of the BOLD data in previous experiments with a similar setup (Dresbach et al, 2023). Thirdly, the longer T1 relaxation period between inversion pulses led to a better structural T1 contrast in the mean VASO EPI image despite a short volume TR (Dresbach et al, 2023).…”

Section: Methodsmentioning

confidence: 98%

“…Secondly, including the delay before the BOLD EPI acquisition increased the temporal SNR (tSNR) of the BOLD data in previous experiments with a similar setup (Dresbach et al, 2023). Thirdly, the longer T1 relaxation period between inversion pulses led to a better structural T1 contrast in the mean VASO EPI image despite a short volume TR (Dresbach et al, 2023). This was especially important in our case, because it would facilitate the registration of images across sessions.…”

Section: Methodsmentioning

confidence: 98%

“…Each stimulus duration was presented once per jitter and run, resulting in at least 21 repetitions per participant. Based on a previous study (Dresbach et al, 2023), 20 repetitions per stimulus constitute a good trade-off between efficiency and data stability. Inter-trial intervals (ITIs) were either 10, 12, 14, 20, and 24 seconds (short ITIs) or 20, 22, 24, 30, and 40 seconds (long ITIs, Figure 1C ).…”

Section: Methodsmentioning

confidence: 99%

“…For example, it allows accounting for carryover effects, enables researchers to study fleeting phenomena such as surprise, or correlate additional factors such as task performance with brain activity. Recently, we have shown that it is feasible to use VASO with short (2 seconds) stimuli and event-related paradigms (Dresbach et al, 2023; for an earlier example of stimuli shorter than 20 seconds, see Persichetti et al, 2020). In this context, we found that stimuli with a duration of 2 seconds had a lower microvascular weighting compared to long stimuli.…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of laminar and vascular spatiotemporal dynamics of CBV and BOLD signals using VASO and ME-GRE at 7T in humans

Dresbach,

Huber,

Gulban

et al. 2024

Preprint

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Interpretation of cortical laminar functional magnetic resonance imaging (fMRI) activity requires detailed knowledge of the spatiotemporal haemodynamic response across vascular compartments due to the well-known vascular biases (e.g. the draining veins). Further complications arise from the spatiotemporal hemodynamic response that differs depending on the duration of stimulation. This information is crucial for future studies using depth-dependent cerebral blood volume (CBV) measurements, which promise higher specificity for the cortical microvasculature than the blood oxygenation level dependent (BOLD) contrast. To date, direct information about CBV dynamics with respect to stimulus duration, cortical depth and vasculature is missing in humans. Therefore, we characterized the cortical depth-dependent CBV-haemodynamic responses across a wide set of stimulus durations with 0.9 mm isotropic spatial and 0.785 seconds effective temporal resolution in humans using slice-selective slab-inversion vascular space occupancy (SS-SI VASO). Additionally, we investigated signal contributions from macrovascular compartments using fine-scale vascular information from multi-echo gradient-echo (ME-GRE) data at 0.35 mm isotropic resolution. In total, this resulted in >7.5h of scanning per participant (n=5). We have three major findings: (I) While we could demonstrate that 1 second stimulation is viable, more than 12 seconds stimulation provides the optimal CBV responses most sensitive to microvasculature, but durations beyond 24 seconds of stimulation may be wasteful for certain applications. (II) We observe that CBV responses show dilation patterns across the cortex. (III) While we found increasingly strong BOLD signal responses in vessel-dominated voxels with longer stimulation durations, we found increasingly strong CBV signal responses in vessel-dominated voxels only until 4 second stimulation durations. After 4 seconds, only the non-vessel dominated voxel signal kept increasing. This might explain why CBV responses are more specific to the underlying neuronal activity for long stimulus durations.

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Section: Discussionsupporting

confidence: 92%

Section: Methodsmentioning

confidence: 98%