scholarly journals Hemodynamic response function in resting brain: disambiguating neural events and autonomic effects

2015 ◽  
Author(s):  
Guorong Wu ◽  
Daniele Marinazzo
Keyword(s):  
Point Process ◽  
Resting State ◽  
Process Analysis ◽  
Cardiac Activity ◽  
Hemodynamic Response ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Bold Signal ◽  
Hemodynamic Response Function ◽  
Blood Oxygen Level

It has been shown that resting state brain dynamics can be characterized by looking at sparse blood-oxygen-level dependent (BOLD) events, which can be retrieved by point process analysis. Cardiac activity can also induce changes in the BOLD signal, thus affect both the number of these events and the mapping between neural events and BOLD signal, namely the hemodynamic response. To isolate neural activity and autonomic effects, we compare the resting state hemodynamic response retrieved by means of a point process analysis with and without deconvolving the cardiac fluctuations. Brainstem and the surrounding cortical area (such as precuneus, insula etc.) are found to be significantly affected by cardiac pulses. Methodological and physiological implications are then discussed.

Retinotopic variations of the negative blood-oxygen-level dependent hemodynamic response function in human primary visual cortex

2021 ◽  
Vol 125 (4) ◽  
pp. 1045-1057 ◽  
Author(s):  
Natasha de la Rosa ◽  
David Ress ◽  
Amanda J. Taylor ◽  
Jung Hwan Kim
Keyword(s):  
Visual Cortex ◽  
Response Function ◽  
Complex Dynamics ◽  
Hemodynamic Response ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Hemodynamic Response Function ◽  
Blood Oxygen Level ◽  
Early Visual Cortex

We investigate dynamics of the negative hemodynamic response function (nHRF), the negative blood-oxygen-level-dependent (BOLD) response (NBR) evoked by a brief stimulus, in human early visual cortex. Here, we show that the nHRFs are not inverted versions of the corresponding pHRFs. The nHRF has complex dynamics that varied significantly with eccentricity. The results also show shift-invariant temporal linearity does not hold for the NBR.

scholarly journals Evaluating Cognitive Relationships with Resting-State and Task-driven Blood Oxygen Level-Dependent Variability

2021 ◽  
Vol 33 (2) ◽  
pp. 279-302
Author(s):  
Peter R. Millar ◽  
Beau M. Ances ◽  
Brian A. Gordon ◽  
Tammie L. S. Benzinger ◽  
John C. Morris ◽  
...  
Keyword(s):  
Task Performance ◽  
Resting State ◽  
Attentional Control ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Bold Signal ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
Age Related ◽  
And Task

Recent functional magnetic resonance imaging studies have reported that moment-to-moment variability in the blood oxygen level-dependent (BOLD) signal is positively associated with task performance and, thus, may reflect a behaviorally sensitive signal. However, it is not clear whether estimates of resting-state and task-driven BOLD variability are differentially related to cognition, as they may be driven by distinct sources of variance in the BOLD signal. Moreover, other studies have suggested that age differences in resting-state BOLD variability may be particularly sensitive to individual differences in cardiovascular, rather than neural, factors. In this study, we tested relationships between measures of behavioral task performance and BOLD variability during both resting-state and task-driven runs of a Stroop and an animacy judgment task in a large, well-characterized sample of cognitively normal middle-aged to older adults. Resting-state BOLD variability was related to composite measures of global cognition and attentional control, but these relationships were eliminated after correction for age or cardiovascular estimates. In contrast, task-driven BOLD variability was related to attentional control measured both inside and outside the scanner, and importantly, these relationships persisted after correction for age and cardiovascular measures. Overall, these results suggest that BOLD variability is a behaviorally sensitive signal. However, resting-state and task-driven estimates of BOLD variability may differ in the degree to which they are sensitive to age-related, cardiovascular, and neural mechanisms.

scholarly journals Sensitivity of the resting-state haemodynamic response function estimation to autonomic nervous system fluctuations

2016 ◽  
Vol 374 (2067) ◽  
pp. 20150190 ◽  
Author(s):  
Guo-Rong Wu ◽  
Daniele Marinazzo
Keyword(s):  
Point Process ◽  
Response Function ◽  
Neural Activity ◽  
Resting State ◽  
Process Analysis ◽  
Low Frequency ◽  
Cardiac Activity ◽  
Haemodynamic Response ◽  
Design Matrix ◽  
Bold Signal

The haemodynamic response function (HRF) is a key component of the blood oxygen level-dependent (BOLD) signal, providing the mapping between neural activity and the signal measured with functional magnetic resonance imaging (fMRI). Most of the time the HRF is associated with task-based fMRI protocols, in which its onset is explicitly included in the design matrix. On the other hand, the HRF also mediates the relationship between spontaneous neural activity and the BOLD signal in resting-state protocols, in which no explicit stimulus is taken into account. It has been shown that resting-state brain dynamics can be characterized by looking at sparse BOLD ‘events’, which can be retrieved by point process analysis. These events can be then used to retrieve the HRF at rest. Crucially, cardiac activity can also induce changes in the BOLD signal, thus affecting both the number of these events and the estimation of the haemodynamic response. In this study, we compare the resting-state haemodynamic response retrieved by means of a point process analysis, taking the cardiac fluctuations into account. We find that the resting-state HRF estimation is significantly modulated in the brainstem and surrounding cortical areas. From the analysis of two high-quality datasets with different temporal and spatial resolution, and through the investigation of intersubject correlation, we suggest that spontaneous point process response durations are associated with the mean interbeat interval and low-frequency power of heart rate variability in the brainstem.

scholarly journals How networks communicate: propagation patterns in spontaneous brain activity

2016 ◽  
Vol 371 (1705) ◽  
pp. 20150546 ◽  
Author(s):  
Anish Mitra ◽  
Marcus E. Raichle
Keyword(s):  
Spontaneous Activity ◽  
Resting State ◽  
Metabolic Cost ◽  
Blood Oxygen Level Dependent ◽  
Temporal Organization ◽  
Intrinsic Activity ◽  
Blood Oxygen ◽  
Bold Signal ◽  
Oxygen Level ◽  
Blood Oxygen Level

Initially regarded as ‘noise’, spontaneous (intrinsic) activity accounts for a large portion of the brain's metabolic cost. Moreover, it is now widely known that infra-slow (less than 0.1 Hz) spontaneous activity, measured using resting state functional magnetic resonance imaging of the blood oxygen level-dependent (BOLD) signal, is correlated within functionally defined resting state networks (RSNs). However, despite these advances, the temporal organization of spontaneous BOLD fluctuations has remained elusive. By studying temporal lags in the resting state BOLD signal, we have recently shown that spontaneous BOLD fluctuations consist of remarkably reproducible patterns of whole brain propagation. Embedded in these propagation patterns are unidirectional ‘motifs’ which, in turn, give rise to RSNs. Additionally, propagation patterns are markedly altered as a function of state, whether physiological or pathological. Understanding such propagation patterns will likely yield deeper insights into the role of spontaneous activity in brain function in health and disease. This article is part of the themed issue ‘Interpreting blood oxygen level-dependent: a dialogue between cognitive and cellular neuroscience’.

scholarly journals A novel method of quantifying hemodynamic delays to improve hemodynamic response, and CVR estimates in CO2 challenge fMRI

2021 ◽  
pp. 0271678X2097858
Author(s):  
Jinxia (Fiona) Yao ◽  
Ho-Ching (Shawn) Yang ◽  
James H Wang ◽  
Zhenhu Liang ◽  
Thomas M Talavage ◽  
...  
Keyword(s):  
Arrival Time ◽  
Stress Test ◽  
Low Frequency ◽  
Hemodynamic Response ◽  
Blood Oxygen Level Dependent ◽  
Cerebrovascular Reactivity ◽  
Bold Signal ◽  
Hemodynamic Response Function ◽  
Carbon Dioxide Co2 ◽  
Co2 Challenge

Elevated carbon dioxide (CO2) in breathing air is widely used as a vasoactive stimulus to assess cerebrovascular functions under hypercapnia (i.e., “stress test” for the brain). Blood-oxygen-level-dependent (BOLD) is a contrast mechanism used in functional magnetic resonance imaging (fMRI). BOLD is used to study CO2-induced cerebrovascular reactivity (CVR), which is defined as the voxel-wise percentage BOLD signal change per mmHg change in the arterial partial pressure of CO2 (PaCO2). Besides the CVR, two additional important parameters reflecting the cerebrovascular functions are the arrival time of arterial CO2 at each voxel, and the waveform of the local BOLD signal. In this study, we developed a novel analytical method to accurately calculate the arrival time of elevated CO2 at each voxel using the systemic low frequency oscillations (sLFO: 0.01-0.1 Hz) extracted from the CO2 challenge data. In addition, 26 candidate hemodynamic response functions (HRF) were used to quantitatively describe the temporal brain reactions to a CO2 stimulus. We demonstrated that our approach improved the traditional method by allowing us to accurately map three perfusion-related parameters: the relative arrival time of blood, the hemodynamic response function, and CVR during a CO2 challenge.

scholarly journals The effect of self- vs. externally generated actions on timing, duration and amplitude of BOLD response for visual feedback processing

2021 ◽  
Author(s):  
Eleftherios Kavroulakis ◽  
Bianca M van Kemenade ◽  
Ezgi B Arikan ◽  
Tilo Kircher ◽  
Benjamin Straube
Keyword(s):  
Hemodynamic Response ◽  
Blood Oxygen Level Dependent ◽  
Neural Processing ◽  
Hemodynamic Response Function ◽  
Subcortical Structures ◽  
Blood Oxygen Level ◽  
Feedback Processing ◽  
Variable Delays ◽  
Custom Made ◽  
Predictive Mechanisms

It has been widely assumed that internal forward models use efference copies to create predictions about the sensory consequences of our own actions. While these predictions had been frequently associated with reduced neural processing in sensory cortices, the timing and duration of the hemodynamic response of self-generated as opposed to externally generated movements is poorly investigated. In the present study we tested the hypothesis that predictive mechanisms for self-generated actions lead to early and shorter neural processing compared with externally generated movements. Using a first and second-order Taylor approximation in terms of the temporal (TD) and dispersion (DD) derivatives of a canonical hemodynamic response function, we investigated the timing and duration of activation for self-generated and externally generated movements using a custom-made fMRI-compatible movement device. Visual video feedback of the active and passive hand movements were presented in real time or with variable delays (0 - 417 ms). Participants had to judge, whether the feedback was delayed. We found earlier feedback processing for self-generated compared to externally generated movements in several regions including the supplementary motor area, cerebellum, subcortical structures such as the putamen and visual cortices. Shorter processing was found in areas, which show also lower blood oxygen level dependent (BOLD) amplitudes, such as the SMA, occipital and parietal cortex. Specifically, earlier activation in the putamen, of self-generated movements was associated with worse performance in detecting delays. These findings support our hypothesis, that efference copy based predictive mechanisms enable earlier processing of action feedback, as potential source for behavioral effects.

scholarly journals Multiple sclerosis-related white matter microstructural change alters the BOLD hemodynamic response

2016 ◽  
Vol 36 (11) ◽  
pp. 1872-1884 ◽  
Author(s):  
Nicholas A Hubbard ◽  
Monroe Turner ◽  
Joanna L Hutchison ◽  
Austin Ouyang ◽  
Jeremy Strain ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
White Matter ◽  
Diffusion Tensor ◽  
Hemodynamic Response ◽  
Blood Oxygen Level Dependent ◽  
Bold Signal ◽  
Hemodynamic Response Function ◽  
Related Factors ◽  
Bold Imaging ◽  
Microstructural Integrity

Multiple sclerosis (MS) results in inflammatory damage to white matter microstructure. Prior research using blood-oxygen-level dependent (BOLD) imaging indicates MS-related alterations to brain function. What is currently unknown is the extent to which white matter microstructural damage influences BOLD signal in MS. Here we assessed changes in parameters of the BOLD hemodynamic response function (HRF) in patients with relapsing-remitting MS compared to healthy controls. We also used diffusion tensor imaging to assess whether MS-related changes to the BOLD-HRF were affected by changes in white matter microstructural integrity. Our results showed MS-related reductions in BOLD-HRF peak amplitude. These MS-related amplitude decreases were influenced by individual differences in white matter microstructural integrity. Other MS-related factors including altered reaction time, limited spatial extent of BOLD activity, elevated lesion burden, or lesion proximity to regions of interest were not mediators of group differences in BOLD-HRF amplitude. Results are discussed in terms of functional hyperemic mechanisms and implications for analysis of BOLD signal differences.

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