Spatially congruent negative BOLD responses to different stimuli do not summate in visual cortex

Wilson, Ross; Thomas, Andrea T; Mayhew, Stephen D.

doi:10.1016/j.neuroimage.2020.116891

Cited by 3 publications

(3 citation statements)

References 88 publications

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“…When observing the averaged subject-level analysis, it seemed that the most prominent cluster was situated in the visual cortex but closer to the parietal lobe, in contrast to pBOLD, which was concentrated at the occipital pole. Although this cluster did not emerge in the grouplevel analysis, its location corresponds to regions of the visual cortex that were identified as non-stimulated during the paradigm and had been previously detected by nBOLD [5].…”

Section: Exploring Neural Activity/deactivation With Bold and Adc Mapsmentioning

confidence: 67%

“…Positive BOLD (pBOLD) is linked to neuronal activity through a process known as neurovascular coupling [3]. In task fMRI, negative BOLD (nBOLD) has been observed in sensory cortices not engaged by the stimulation paradigm, such as the deactivation of the auditory cortex during a visual task [4,5]. However, it remains unclear whether nBOLD during a task reflects neural inhibition or results from a 'blood-steal' effect [6].…”

Section: Introductionmentioning

confidence: 99%

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Mapping activity and functional organisation of the motor and visual pathways using ADC-fMRI in the human brain

Nguyen-Duc,

de Riedmatten,

Spencer

et al. 2024

Preprint

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In contrast to blood-oxygenation-level-dependent (BOLD) functional MRI (fMRI), which relies on changes in blood flow and oxygenation levels to infer brain activity, diffusion fMRI (DfMRI) investigates brain dynamics by monitoring alterations in the Apparent Diffusion Coefficient (ADC) of water. These ADC changes may arise from fluctuations in neuronal morphology, providing a distinctive perspective on neural activity. The potential of ADC as an fMRI contrast (ADC-fMRI) lies in its capacity to reveal neural activity independently of neurovascular coupling, thus yielding complementary insights into brain function.To demonstrate the specificity and value of ADC-fMRI, both ADC-and BOLD-fMRI data were collected at 3T in human subjects during visual stimulation and motor tasks. The first aim of this study was to identify an acquisition design for ADC that minimises BOLD contributions. By examining the timings in responses, we report that ADC 0/1 timeseries (acquired with b-values of 0 and 1 ms/µm2) exhibit residual vascular contamination while ADC 0.2/1 timeseries (with b-values of 0.2 and 1 ms/µm2) show minimal BOLD influence and higher sensitivity to neuromorphological coupling. Second, a General Linear Model was employed to identify activation clusters for ADC 0.2/1 and BOLD, from which average ADC and BOLD responses were calculated. The negative ADC response exhibited a significantly reduced delay relative to the task onset and offset as compared to BOLD. This early onset further supports the notion that ADC is sensitive to neuromorphological rather than neurovascular coupling. Remarkably, in the group-level analysis, positive BOLD activation clusters were detected in the visual and motor cortices, while the negative ADC clusters mainly highlighted pathways in white matter connected to the motor cortex. In the averaged individual level analysis, negative ADC activation clusters were also present in the visual cortex. This finding confirmed the reliability of negative ADC as an indicator of brain function, even in regions with lower vascularisation such as white matter. Finally, we established that ADC-fMRI timecourses yield the expected functional organisation of the visual system, including both gray and white matter regions of interest. Functional connectivity matrices were used to perform hierarchical clustering of brain regions, where ADC-fMRI successfully reproduced the expected structure of the dorsal and ventral visual pathways. This organisation was not replicated with the b=0.2 ms/µm2diffusion-weighted time courses, which can be seen as a proxy for BOLD (viaT2-weighting). These findings underscore the robustness of ADC time courses in functional MRI studies, offering complementary insights to BOLD-fMRI regarding brain function and connectivity patterns.KeypointsThe functional time course of the Apparent Diffusion Coefficient (ADC), specifically measured with alternating b-values of 0.2 and 1 ms/µm2at 3T, appears to be minimally affected by BOLD contamination.In the activity maps, the location of negative ADC clusters suggests neural activity in WM tracts that are connected to the motor cortex, which is not detected with positive BOLD.Functional Connectivity analysis utilising ADC is better able to detect the organisation of the dorsal and ventral visual streams than diffusion- andT2-weighted time courses.

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Section: Exploring Neural Activity/deactivation With Bold and Adc Mapsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Mapping activity and functional organisation of the motor and visual pathways using ADC-fMRI in the human brain

Nguyen-Duc,

de Riedmatten,

Spencer

et al. 2024

Preprint

View full text Add to dashboard Cite

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“…Especially in respect to nociceptive stimuli, studies have shown that those might trigger local deactivation or inhibition of the corresponding brain areas and therefore a different hemodynamic response than activations following nonnociceptive stimuli (Apkarian et al, 1992; Disbrow, Buonocore, Antognini, Carstens, & Rowley, 1998). In connection with this phenomenon, there is ongoing discussion about the role of the universally observed negative Blood‐Oxygenation‐Level‐Dependent (BOLD) response in fMRI (Tal, Geva, & Amedi, 2017; Wilson, Thomas, & Mayhew, 2020). It is interpreted most commonly as neuronal deactivation or inhibition (Stefanovic, Warnking, & Pike, 2004; Sten et al, 2017), but some studies are revealing a more complex situation since different hemodynamic mechanisms at various depth layers of the brain might be the trigger for the positive BOLD response (PBR) and the negative BOLD response (NBR) (Goense, Merkle, & Logothetis, 2012; Huber et al, 2014; Mullinger, Mayhew, Bagshaw, Bowtell, & Francis, 2014).…”

Section: Introductionmentioning

confidence: 99%

Characterization of cortical hemodynamic changes following sensory, visual, and speech activation by intraoperative optical imaging utilizing phase‐based evaluation methods

Oelschlägel

Polanski

Morgenstern

et al. 2021

Human Brain Mapping

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Alterations within cerebral hemodynamics are the intrinsic signal source for a wide variety of neuroimaging techniques. Stimulation of specific functions leads due to neurovascular coupling, to changes in regional cerebral blood flow, oxygenation and volume. In this study, we investigated the temporal characteristics of cortical hemodynamic responses following electrical, tactile, visual, and speech activation for different stimulation paradigms using Intraoperative Optical Imaging (IOI). Image datasets from a total of 22 patients that underwent surgical resection of brain tumors were evaluated. The measured reflectance changes at different light wavelength bands, representing alterations in regional cortical blood volume (CBV), and deoxyhemoglobin (HbR) concentration, were assessed by using Fourier-based evaluation methods. We found a decrease of CBV connected to an increase of HbR within the contralateral primary sensory cortex (SI) in patients that were prolonged (30 s/15 s) electrically stimulated. Additionally, we found differences in amplitude as well as localization of activated areas for different stimulation patterns. Contrary to electrical stimulation, prolonged tactile as well as prolonged visual stimulation are provoking increases in CBV within the corresponding activated areas (SI, visual cortex). The processing of the acquired data from awake patients performing speech tasks reveals areas with increased, as well as areas with decreased CBV. The results lead us to the conclusion, that the CBV decreases in connection with HbR increases

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The Relationship Between Cognition and Cerebrovascular Reactivity: Implications for Task-Based fMRI

et al. 2021

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Elucidating the brain regions and networks associated with cognitive processes has been the mainstay of task-based fMRI, under the assumption that BOLD signals are uncompromised by vascular function. This is despite the plethora of research highlighting BOLD modulations due to vascular changes induced by disease, drugs, and aging. On the other hand, BOLD fMRI-based assessment of cerebrovascular reactivity (CVR) is often used as an indicator of the brain's vascular health and has been shown to be strongly associated with cognitive function. This review paper considers the relationship between BOLD-based assessments of CVR, cognition and task-based fMRI. How the BOLD response reflects both CVR and neural activity, and how findings of altered CVR in disease and in normal physiology are associated with cognition and BOLD signal changes are discussed. These are pertinent considerations for fMRI applications aiming to understand the biological basis of cognition. Therefore, a discussion of how the acquisition of BOLD-based CVR can enhance our ability to map human brain function, with limitations and potential future directions, is presented.

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Spatially congruent negative BOLD responses to different stimuli do not summate in visual cortex

Cited by 3 publications

References 88 publications

Mapping activity and functional organisation of the motor and visual pathways using ADC-fMRI in the human brain

Mapping activity and functional organisation of the motor and visual pathways using ADC-fMRI in the human brain

Characterization of cortical hemodynamic changes following sensory, visual, and speech activation by intraoperative optical imaging utilizing phase‐based evaluation methods

The Relationship Between Cognition and Cerebrovascular Reactivity: Implications for Task-Based fMRI

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