scholarly journals Resting-state functional MRI signal fluctuations are correlated with brain amyloid-β deposition

2021 ◽  
Author(s):  
Norman Scheel ◽  
Takashi Tarumi ◽  
Tsubasa Tomoto ◽  
Munro Cullum ◽  
Rong Zhang ◽  
...  
Keyword(s):  
Functional Mri ◽  
Resting State ◽  
Low Frequency ◽  
Amyloid Β ◽  
Standardized Uptake Value ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Blood Oxygen Level ◽  
Positron Emission ◽  
Local Correlations

Mounting evidence suggests that amyloid-β (Aβ) and vascular etiologies are intertwined in the pathogenesis of Alzheimer′s disease. Spontaneous fluctuations of the brain blood-oxygen-level-dependent (BOLD) signal, as measured by resting-state functional MRI (rs-fMRI), have been shown to be associated with neuronal activities as well as cerebrovascular hemodynamics. Nevertheless, it is unclear if rs-fMRI BOLD fluctuations are associated with brain Aβ deposition in individuals with an elevated risk of Alzheimer's disease. We recruited 33 patients with amnestic mild cognitive impairment who underwent rs-fMRI and positron emission tomography (PET). The Aβ standardized uptake value ratio (SUVR) was calculated with cortical white matter as the reference region to improve sensitivity for cortical Aβ quantification. We calculated the amplitudes of low-frequency fluctuations (ALFF) of local BOLD signals in the frequency band of 0.01-0.08 Hz. Applying physiological/vascular signal regression in stepwise increasing levels on the rs-fMRI data, we examined whether local correlations between ALFF and brain Aβ deposition were driven by vascular hemodynamics, spontaneous neuronal activities, or both. We found that ALFF and Aβ SUVR were negatively correlated in brain regions involving the default-mode and visual networks, with peak correlation at the precuneus, and angular, lingual, and fusiform gyri. Regions with higher ALFF had less Aβ accumulation. The correlated cluster sizes in MNI space were reduced from 3018 mm3 with no physiological/vascular regression to 1072 mm3 with strong physiological/vascular regression, with mean cluster r values at approximately -0.47. Results demonstrate that both vascular hemodynamics and neuronal activities, as reflected by BOLD fluctuations, are negatively associated with brain Aβ deposition. These findings further imply that local brain blood fluctuations due to either vascular hemodynamics or neuronal activities can affect Aβ homeostasis.

Resting-state functional MRI signal fluctuation amplitudes are correlated with brain amyloid-β deposition in patients with mild cognitive impairment

2021 ◽  
pp. 0271678X2110648
Author(s):  
Norman Scheel ◽  
Takashi Tarumi ◽  
Tsubasa Tomoto ◽  
C Munro Cullum ◽  
Rong Zhang ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Functional Mri ◽  
Neuronal Activity ◽  
Resting State ◽  
Low Frequency ◽  
Amyloid Β ◽  
Standardized Uptake Value ◽  
Blood Oxygen Level Dependent ◽  
Cerebral White Matter

Mounting evidence suggests that amyloid-β (Aβ) and vascular etiologies are intertwined in the pathogenesis of Alzheimer’s disease (AD). Blood-oxygen-level-dependent (BOLD) signals, measured by resting-state functional MRI (rs-fMRI), are associated with neuronal activity and cerebrovascular hemodynamics. Nevertheless, it is unclear if BOLD fluctuations are associated with Aβ deposition in individuals at high risk of AD. Thirty-three patients with amnestic mild cognitive impairment underwent rs-fMRI and AV45 PET. The AV45 standardized uptake value ratio (AV45-SUVR) was calculated using cerebral white matter as reference, to assess Aβ deposition. The whole-brain normalized amplitudes of low-frequency fluctuations (sALFF) of local BOLD signals were calculated in the frequency band of 0.01–0.08 Hz. Stepwise increasing physiological/vascular signal regressions on the rs-fMRI data examined whether sALFF-AV45 correlations were driven by vascular hemodynamics, neuronal activities, or both. We found that sALFF and AV45-SUVR were negatively correlated in regions of default-mode and visual networks (precuneus, angular, lingual and fusiform gyri). Regions with higher sALFF had less Aβ accumulation. Correlated cluster sizes in MNI space ( r ≈ −0.47) were reduced from 3018 mm3 to 1072 mm3 with stronger cardiovascular regression. These preliminary findings imply that local brain blood fluctuations due to vascular hemodynamics or neuronal activity can affect Aβ homeostasis.

Functional MRI

2018 ◽  
Keyword(s):  
Functional Mri ◽  
Resting State ◽  
Brain Activity ◽  
Low Frequency ◽  
Resting State Fmri ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Functional Brain Imaging ◽  
Fmri Signal ◽  
The Brain

Functional MRI with BOLD (Blood Oxygen Level Dependent) imaging is one of the commonly used modalities for studying brain function in neuroscience. The underlying source of the BOLD fMRI signal is the variation in oxyhemoglobin to deoxyhemoglobin ratio at the site of neuronal activity in the brain. fMRI is mostly used to map out the location and intensity of brain activity that correlate with mental activities. In recent years, a new approach to fMRI was developed that is called resting-state fMRI. The fMRI signal from this method does not require the brain to perform any goal-directed task; it is acquired with the subject at rest. It was discovered that there are low-frequency fluctuations in the fMRI signal in the brain at rest. The signals originate from spatially distinct functionally related brain regions but exhibit coherent time-synchronous fluctuations. Several of the networks have been identified and are called resting-state networks. These networks represent the strength of the functional connectivity between distinct functionally related brain regions and have been used as imaging markers of various neurological and psychiatric diseases. Resting-state fMRI is also ideally suited for functional brain imaging in disorders of consciousness and in subjects under anesthesia. This book provides a review of the basic principles of fMRI (signal sources, acquisition methods, and data analysis) and its potential clinical applications.

scholarly journals Differential effects of anesthetics on resting state functional connectivity in the mouse

2019 ◽  
Vol 40 (4) ◽  
pp. 875-884 ◽  
Author(s):  
Hongyu Xie ◽  
David Y Chung ◽  
Sreekanth Kura ◽  
Kazutaka Sugimoto ◽  
Sanem A Aykan ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
Chloral Hydrate ◽  
Low Frequency ◽  
Blood Oxygen Level Dependent ◽  
Resting State Functional Connectivity ◽  
Blood Oxygen Level ◽  
Intrinsic Signal ◽  
Optical Intrinsic Signal ◽  
Important Approach

Blood oxygen level-dependent (BOLD) functional MRI (fMRI) is a standard approach to examine resting state functional connectivity (RSFC), but fMRI in animal models is challenging. Recently, functional optical intrinsic signal imaging—which relies on the same hemodynamic signal underlying BOLD fMRI—has been developed as a complementary approach to assess RSFC in mice. Since it is difficult to ensure that an animal is in a truly resting state while awake, RSFC measurements under anesthesia remain an important approach. Therefore, we systematically examined measures of RSFC using non-invasive, widefield optical intrinsic signal imaging under five different anesthetics in male C57BL/6J mice. We find excellent seed-based, global, and interhemispheric connectivity using tribromoethanol (Avertin) and ketamine–xylazine, comparable to results in the literature including awake animals. Urethane anesthesia yielded intermediate results, while chloral hydrate and isoflurane were both associated with poor RSFC. Furthermore, we found a correspondence between the strength of RSFC and the power of low-frequency hemodynamic fluctuations. In conclusion, Avertin and ketamine–xylazine provide robust and reproducible measures of RSFC in mice, whereas chloral hydrate and isoflurane do not.

A Resting-State Functional MRI Study in Patients with Vestibular Migraine During Interictal Period

2020 ◽  
Author(s):  
Shuqing Wang ◽  
Haiping Wang ◽  
Xuejun Liu ◽  
Wenjing Yan ◽  
Minghui Wang ◽  
...  
Keyword(s):  
Functional Mri ◽  
Resting State ◽  
Low Frequency ◽  
Region Of Interest ◽  
Resting State Fmri ◽  
Brain Regions ◽  
Vestibular Migraine ◽  
Lingual Gyrus ◽  
The Right ◽  
Mri Study

Abstract AimTo evaluate the spontaneous neuronal activities and the changes of brain functional network in patients with vestibular migraine (VM) using resting-state functional MRI (fMRI) during the interictal period.MethodsThree groups included 18 patients with VM, 21 patients with MWoA and 21 HCs underwent the scanning of the resting-state fMRI. First, brain regions with significant differentia of amplitude of low frequency fluctuation (ALFF) values were obtained. Secondly, functional connectivity (FC) analysis was performed in the brain region(s) with the most significant differentia of ALFF values which was defined as region of interest (ROI).Results(1) Compared with healthy volunteers, patients with VM and patients with MWoA showed significant ALFF decrease in the right putamen (P<0.05), and significant ALFF increase in the right lingual gyrus (P<0.05). What’s more, compared with patients with MWoA, patients with VM showed significant ALFF increase in the right lingual gyrus (P<0.05). In addition, we found that ALFF values in the right putamen of patients with VM were negatively correlated with the duration of migraine and the frequency of migraine attacks (P<0.05). (2) Compared with HCs, patients with VM showed significant FC increase among the cerebellum, the left dorsolateral superior frontal gyrus and the right putamen (P<0.05) but significant decrease among the left median cingulate, paracingulate gyri and the right putamen (P<0.05). Compared with patients with MWoA, patients with VM showed significant FC increase between the cerebellum and the right putamen (P<0.05) but significant FC decrease among the left median cingulate, paracingulate gyri and the right putamen (P<0.05).ConclusionThere are functional abnormalities in nociceptive, vestibular and visual cortex regions in patients with VM during the interictal period.

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 Mild inflammation causes a reduction in resting-state amplitude of low-frequency fluctuation in healthy adult males

2020 ◽  
Vol 4 ◽  
pp. 239821282094935
Author(s):  
Kristian Stefanov ◽  
John McLean ◽  
Becky Allan ◽  
Jonathan Cavanagh ◽  
Rajeev Krishnadas
Keyword(s):  
Resting State ◽  
Low Frequency ◽  
Blood Oxygen Level Dependent ◽  
Mood States ◽  
Profile Of Mood States ◽  
Blood Oxygen ◽  
Blood Oxygen Level ◽  
Lower Amplitude ◽  
Frequency Fluctuations ◽  
The Right

Systemic inflammation has been associated with negative mood states and human sickness behaviour. Previous studies have shown an association between systemic inflammation and changes in task-related blood-oxygen-level-dependent activity and functional connectivity within large-scale networks. However, no study has examined the effect of inflammation on the magnitude of blood-oxygen-level-dependent low-frequency fluctuations at rest. We used a double-blind placebo-controlled crossover design to randomise 20 male subjects (aged 20–50 years) to receive either a Salmonella typhi vaccine or a placebo saline injection at two separate sessions. All participants underwent a resting-state functional magnetic resonance scan and a measure of inflammation (interleukin 6) and mood (Profile of Mood States) 3 h after injection. We compared the whole brain amplitude of low-frequency fluctuations between the vaccine and placebo conditions using a repeated measures design. Vaccine condition was associated with greater interleukin 6 levels (p < 0.001). Vaccine condition was also associated with lower amplitude of low-frequency fluctuations in the right and left frontal pole, superior frontal gyrus, paracingulate gyrus (Cluster 1) and the right mid and inferior frontal gyrus (Cluster 2) (p < 0.001, false discovery rate corrected). Lower amplitude of low-frequency fluctuations pertaining to first cluster correlated with greater total Profile of Mood States score (worse mood) (r = −0.38; p = 0.04). These results imply possible excitation/inhibition imbalance mechanisms during inflammation that may be a relevant target in psychiatric disease, especially mood disorders.

scholarly journals Metabolic Origin of Bold Signal Fluctuations in the Absence of Stimuli

2008 ◽  
Vol 28 (7) ◽  
pp. 1377-1387 ◽  
Author(s):  
Masaki Fukunaga ◽  
Silvina G Horovitz ◽  
Jacco A de Zwart ◽  
Peter van Gelderen ◽  
Thomas J Balkin ◽  
...  
Keyword(s):  
Resting State ◽  
Human Subjects ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Breath Holding ◽  
Metabolic Demand ◽  
Blood Oxygen Level ◽  
Healthy Human ◽  
State Activity ◽  
Significant Difference

Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging studies have shown the existence of ongoing blood flow fluctuations in the absence of stimuli. Although this so-called ‘resting-state activity’ appears to be correlated across brain regions with apparent functional relationship, its origin might be predominantly vascular and not directly representing neuronal signaling. To investigate this, we simultaneously measured BOLD and perfusion signals on healthy human subjects ( n = 11) and used their ratio (BOLD/perfusion ratio or BPR) as an indicator of metabolic demand. BPR during rest and sleep was compared with that during a visual task (VT) and a breath-holding task (BH), which are challenges with substantial and little metabolic involvement, respectively. Within the visual cortex, BPR was 3.76 ± 1.23 during BH, which was significantly higher than during the VT (1.76 ± 0.27) and rest (1.56 ± 0.41). Meanwhile, BPR values during VT and rest were not significantly different, suggesting a similar metabolic involvement. Eight subjects showed stage 1 and 2 sleep, during which temporally correlated BOLD and perfusion activity continued. In these subjects, there was no significant difference in BPR between the sleep and waking conditions (1.79 ± 0.54 and 1.66 ± 0.67, respectively), but both were lower than the BPR during BH. These data suggest that resting-state activity, at least in part, represents a metabolic process.

scholarly journals Resting-State Blood Oxygen Level-Dependent Functional MRI: A Paradigm Shift in Preoperative Brain Mapping

2015 ◽  
Vol 93 (6) ◽  
pp. 427-439 ◽  
Author(s):  
Eric C. Leuthardt ◽  
Monica Allen ◽  
Mudassar Kamran ◽  
Ammar H. Hawasli ◽  
Abraham Z. Snyder ◽  
...  
Keyword(s):  
Functional Mri ◽  
Brain Mapping ◽  
Resting State ◽  
Paradigm Shift ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level

scholarly journals Mapping cognitive and emotional networks in neurosurgical patients using resting-state functional magnetic resonance imaging

2020 ◽  
Vol 48 (2) ◽  
pp. E9 ◽  
Author(s):  
Michael P. Catalino ◽  
Shun Yao ◽  
Deborah L. Green ◽  
Edward R. Laws ◽  
Alexandra J. Golby ◽  
...  
Keyword(s):  
Resting State ◽  
Imaging Modality ◽  
Low Frequency ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen Level ◽  
Brain Functions ◽  
Neurosurgical Patients ◽  
Potential Applications ◽  
Dependent Signal ◽  
Intraoperative Electrical Stimulation

Neurosurgery has been at the forefront of a paradigm shift from a localizationist perspective to a network-based approach to brain mapping. Over the last 2 decades, we have seen dramatic improvements in the way we can image the human brain and noninvasively estimate the location of critical functional networks. In certain patients with brain tumors and epilepsy, intraoperative electrical stimulation has revealed direct links between these networks and their function. The focus of these techniques has rightfully been identification and preservation of so-called “eloquent” brain functions (i.e., motor and language), but there is building momentum for more extensive mapping of cognitive and emotional networks. In addition, there is growing interest in mapping these functions in patients with a broad range of neurosurgical diseases. Resting-state functional MRI (rs-fMRI) is a noninvasive imaging modality that is able to measure spontaneous low-frequency blood oxygen level–dependent signal fluctuations at rest to infer neuronal activity. Rs-fMRI may be able to map cognitive and emotional networks for individual patients. In this review, the authors give an overview of the rs-fMRI technique and associated cognitive and emotional resting-state networks, discuss the potential applications of rs-fMRI, and propose future directions for the mapping of cognition and emotion in neurosurgical patients.

Basic Principles of Functional MRI

2018 ◽  
pp. 20-29
Author(s):  
Cheuk Ying Tang
Keyword(s):  
Functional Mri ◽  
Resting State ◽  
Brain Activity ◽  
Low Frequency ◽  
Resting State Fmri ◽  
Brain Regions ◽  
Functional Brain Imaging ◽  
Basic Principles ◽  
Fmri Signal ◽  
The Brain

Blood oxygen level dependent (BOLD) MRI, also called functional MRI (fMRI), is one of the most widely used modalities for studying brain function. The underlying source of the fMRI signal is blood flow and the oxygenation state of hemoglobin. fMRI is mostly used to map out the location and intensity of brain activity that correlate with mental activities. In recent years, a new approach to fMRI has been developed that is called resting-state fMRI. The fMRI signal from this method does not require the brain to perform a goal-directed task; it is acquired with the subject at rest. It was discovered that there are low-frequency fluctuations in the fMRI signal in the brain at rest. These signals come from spatially distinct brain regions but exhibit coherent, time-synchronous fluctuations. Several of the networks have been identified and are called resting-state networks. The networks represent the strength of the functional connectivity between distinct brain regions and have been used as imaging biomarkers for various neurological and psychiatric diseases. Resting-state fMRI is also ideally suited for functional brain imaging in disorders of consciousness and in subjects under anesthesia. In this chapter, we provide an introductory review of the basic principles of fMRI: signal sources, acquisition methods, and data analysis.

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