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 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.

scholarly journals Disrupted Spontaneous Neural Activity in Patients With Thyroid-Associated Ophthalmopathy: A Resting-State fMRI Study Using Amplitude of Low-Frequency Fluctuation

2021 ◽  
Vol 15 ◽  
Author(s):  
Wen Chen ◽  
Qian Wu ◽  
Lu Chen ◽  
Jiang Zhou ◽  
Huan-Huan Chen ◽  
...  
Keyword(s):  
Neural Activity ◽  
Resting State ◽  
Low Frequency ◽  
Occipital Lobe ◽  
Frequency Fluctuation ◽  
Clinical Activity ◽  
Spontaneous Neural Activity ◽  
Thyroid Associated Ophthalmopathy ◽  
Middle Occipital Gyrus ◽  
Left Middle

PurposeThe purpose of the study was to investigate the brain functional alteration in patients with thyroid-associated ophthalmopathy (TAO) by evaluating the spontaneous neural activity changes using resting-state functional magnetic resonance imaging (rs-fMRI) with the amplitude of low-frequency fluctuation (ALFF) method.Materials and MethodsThe rs-fMRI data of 30 TAO patients (15 active and 15 inactive) and 15 healthy controls (HCs) were included for analyses. The ALFF values were calculated and compared among groups. Correlations between ALFF values and clinical metrics were assessed.ResultsCompared with HCs, active TAOs showed significantly decreased ALFF values in the left middle occipital gyrus, superior occipital gyrus, and cuneus. Compared with inactive TAOs, active TAOs showed significantly increased ALFF values in the bilateral precuneus. Additionally, inactive TAOs showed significantly decreased ALFF values in the left middle occipital gyrus, superior occipital gyrus, cuneus, and bilateral precuneus than HCs. The ALFF value in the right precuneus of TAOs was positively correlated with clinical activity score (r = 0.583, P < 0.001) and Mini-Mental State Examination (MMSE) score (r = 0.377, P = 0.040), and negatively correlated with disease duration (r = −0.382, P = 0.037). Moreover, the ALFF value in the left middle occipital gyrus of TAOs was positively correlated with visual acuity (r = 0.441, P = 0.015).ConclusionTAO patients had altered spontaneous brain activities in the left occipital lobe and bilateral precuneus. The neuropsychological aspect of the disease should be noticed during clinical diagnosis and treatment.

scholarly journals Subcortical connectivity in dementia with Lewy bodies and Alzheimer's disease

2013 ◽  
Vol 203 (3) ◽  
pp. 209-214 ◽  
Author(s):  
Eva R. Kenny ◽  
John T. O'Brien ◽  
Michael J. Firbank ◽  
Andrew M. Blamire
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Connectivity ◽  
Resting State ◽  
Dementia With Lewy Bodies ◽  
Lewy Bodies ◽  
Low Frequency ◽  
Blood Oxygen Level Dependent ◽  
Bold Signal ◽  
Blood Oxygen Level

BackgroundResting-state functional magnetic resonance imaging (fMRI) can be used to measure correlations in spontaneous low-frequency fluctuations in the blood oxygen level-dependent (BOLD) signal which represent functional connectivity between key brain areas.AimsTo investigate functional connectivity with regions hypothesised to be differentially affected in dementia with Lewy bodies (DLB) compared with Alzheimer's disease and controls.MethodFifteen participants with probable DLB, 16 with probable Alzheimer's disease and 16 controls were scanned in the resting-state using a 3T scanner. The BOLD signal time-series of fluctuations in seed regions were correlated with all other voxels to measure functional connectivity.ResultsParticipants with DLB and Alzheimer's disease showed greater caudate and thalamic connectivity compared with controls. Those with DLB showed greater putamen connectivity compared with those with Alzheimer's disease and the controls. No regions showed less connectivity in DLB or Alzheimer's disease v. controls, or in DLB v. Alzheimer's disease.ConclusionsAltered connectivity in DLB and Alzheimer's disease provides new insights into the neurobiology of these disorders and may aid in earlier diagnosis.

scholarly journals Different dynamic resting state fMRI patterns are linked to different frequencies of neural activity

2015 ◽  
Vol 114 (1) ◽  
pp. 114-124 ◽  
Author(s):  
Garth John Thompson ◽  
Wen-Ju Pan ◽  
Shella Dawn Keilholz
Keyword(s):  
Neural Activity ◽  
Attention Deficit Disorder ◽  
Resting State ◽  
Low Frequency ◽  
Resting State Fmri ◽  
Periodic Patterns ◽  
Limited Power ◽  
Band Limited ◽  
Additional Support ◽  
Network Mapping

Resting state functional magnetic resonance imaging (rsfMRI) results have indicated that network mapping can contribute to understanding behavior and disease, but it has been difficult to translate the maps created with rsfMRI to neuroelectrical states in the brain. Recently, dynamic analyses have revealed multiple patterns in the rsfMRI signal that are strongly associated with particular bands of neural activity. To further investigate these findings, simultaneously recorded invasive electrophysiology and rsfMRI from rats were used to examine two types of electrical activity (directly measured low-frequency/infraslow activity and band-limited power of higher frequencies) and two types of dynamic rsfMRI (quasi-periodic patterns or QPP, and sliding window correlation or SWC). The relationship between neural activity and dynamic rsfMRI was tested under three anesthetic states in rats: dexmedetomidine and high and low doses of isoflurane. Under dexmedetomidine, the lightest anesthetic, infraslow electrophysiology correlated with QPP but not SWC, whereas band-limited power in higher frequencies correlated with SWC but not QPP. Results were similar under isoflurane; however, the QPP was also correlated to band-limited power, possibly due to the burst-suppression state induced by the anesthetic agent. The results provide additional support for the hypothesis that the two types of dynamic rsfMRI are linked to different frequencies of neural activity, but isoflurane anesthesia may make this relationship more complicated. Understanding which neural frequency bands appear as particular dynamic patterns in rsfMRI may ultimately help isolate components of the rsfMRI signal that are of interest to disorders such as schizophrenia and attention deficit disorder.

scholarly journals Delta Rhythm Orchestrates the Neural Activity Underlying the Resting State BOLD Signal via Phase–amplitude Coupling

2017 ◽  
Vol 29 (1) ◽  
pp. 119-133 ◽  
Author(s):  
Saul Jaime ◽  
Hong Gu ◽  
Brian F Sadacca ◽  
Elliot A Stein ◽  
Jose E Cavazos ◽  
...  
Keyword(s):  
Neural Activity ◽  
Resting State ◽  
Bold Signal ◽  
Delta Rhythm ◽  
Phase Amplitude

scholarly journals Tailored haemodynamic response function increases detection power of fMRI in awake dogs (Canis familiaris)

2020 ◽  
Author(s):  
Magdalena Boch ◽  
Sabrina Karl ◽  
Ronald Sladky ◽  
Ludwig Huber ◽  
Claus Lamm ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Response Function ◽  
Visual Stimulation ◽  
Canis Familiaris ◽  
Temporal Cortex ◽  
Model Fit ◽  
Haemodynamic Response ◽  
List Type ◽  
Bold Signal ◽  
Detection Power

AbstractFunctional magnetic resonance imaging (fMRI) of awake and unrestrained dogs (Canis familiaris) has been established as a novel opportunity for comparative neuroimaging, promising important insights into the evolutionary roots of human brain function and cognition. However, data processing and analysis pipelines are often derivatives of methodological standards developed for human neuroimaging, which may be problematic due to profound neurophysiological and anatomical differences between humans and dogs. Here, we explore whether dog fMRI studies would benefit from a tailored dog haemodynamic response function (HRF). In two independent experiments, dogs were presented with different visual stimuli. BOLD signal changes in the visual cortex during these experiments were used for (a) the identification and estimation of a tailored dog HRF, and (b) the independent validation of the resulting dog HRF estimate. Time course analyses revealed that the BOLD signal in the primary visual cortex peaks significantly earlier in dogs compared to humans, while being comparable in shape. Deriving a tailored dog HRF significantly improved the model fit in both experiments, compared to the canonical HRF used in human fMRI. Using the dog HRF yielded significantly increased activation during visual stimulation, extending from the occipital lobe, to the caudal parietal cortex, the bilateral temporal cortex, and into bilateral hippocampal and thalamic regions. In sum, our findings provide robust evidence for an earlier onset of the dog HRF in a visual stimulation paradigm, and suggest that using such an HRF will be important to increase fMRI detection power in canine neuroimaging. By providing the parameters of the tailored dog HRF and related code, we encourage and enable other researchers to validate whether our findings generalize to other sensory modalities and experimental paradigms.HighlightsDog fMRI typically uses human HRF, but underlying neurophysiology might differV1 BOLD signal peaked earlier in dogs than predicted by the human HRFTailored dog HRF improved model fit when tested with independent dataWhole-brain comparisons confirmed increased detection power for tailored dog HRFDog fMRI will benefit from increased detection power of tailored HRF

Modeling the hemodynamic response function using EEG-fMRI data during eyes-open resting-state conditions and motor task execution

2020 ◽  
Author(s):  
Prokopis C. Prokopiou ◽  
Alba Xifra-Porxas ◽  
Michalis Kassinopoulos ◽  
Marie-Hélène Boudrias ◽  
Georgios D. Mitsis
Keyword(s):  
Response Function ◽  
Resting State ◽  
Motor Task ◽  
Field Potential ◽  
Hemodynamic Response ◽  
Bold Signal ◽  
Hemodynamic Response Function ◽  
Beta Band ◽  
Experimental Conditions ◽  
Frequency Bands

AbstractIn this work, we investigated the regional characteristics of the dynamic interactions between oscillatory sources of ongoing neural activity obtained using electrophysiological recordings and the corresponding changes in the BOLD signal using simultaneous EEG-fMRI measurements acquired during a motor task, as well as under resting conditions. We casted this problem within a system-theoretic framework, where we initially performed distributed EEG source space reconstruction and subsequently employed block-structured linear and non-linear models to predict the BOLD signal from the instantaneous power in narrow frequency bands of the source local field potential (LFP) spectrum (<100 Hz). Our results suggest that the dynamics of the BOLD signal can be sufficiently described as the convolution between a linear combination of the power profile within individual frequency bands with a hemodynamic response function (HRF). During the motor task, BOLD signal variance was mainly explained by the EEG oscillations in the beta band. On the other hand, during resting-state all frequency bands of EEG exhibited significant contributions to BOLD signal variance. Moreover, the contribution of each band was found to be region specific. Our results also revealed considerable variability of the HRF across different brain regions. Specifically, sensory-motor cortices exhibited positive HRF shapes, whereas parietal and occipital cortices exhibited negative HRF shapes under both experimental conditions.

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