Search results for "Resting state"
showing 10 items of 59 documents
Resting-state posterior alpha rhythms are abnormal in subjective memory complaint seniors with preclinical Alzheimer's neuropathology and high educat…
2020
International audience; Cognitive reserve is present in Alzheimer's disease (AD) seniors with high education attainment making them clinically resilient to extended brain neuropathology and neurodegeneration. Here, we tested whether subjective memory complaint (SMC) seniors with AD neuropathology and high education attainment of the prospective INSIGHT-preAD cohort (Paris) may present abnormal eyesclosed resting state posterior electroencephalographic rhythms around individual alpha frequency peak, typically altered in AD patients. The SMC participants negative to amyloid PET AD markers (SMCneg) with high (over low-moderate) education level showed higher posterior alpha 2 power density (pos…
Cerebello-cortical network fingerprints differ between essential, Parkinson's and mimicked tremors.
2017
Cerebello-thalamo-cortical loops play a major role in the emergence of pathological tremors and voluntary rhythmic movements. It is unclear whether these loops differ anatomically or functionally in different types of tremor. We compared age- and sex-matched groups of patients with Parkinson's disease or essential tremor and healthy controls (n = 34 per group). High-density 256-channel EEG and multi-channel EMG from extensor and flexor muscles of both wrists were recorded simultaneously while extending the hands against gravity with the forearms supported. Tremor was thereby recorded from patients, and voluntarily mimicked tremor was recorded from healthy controls. Tomographic maps of EEG-E…
Reductive Stress: A New Concept in Alzheimer's Disease
2015
Reactive oxygen species play a physiological role in cell signaling and also a pathological role in diseases, when antioxidant defenses are overwhelmed causing oxidative stress. However, in this review we will focus on reductive stress that may be defined as a pathophysiological situation in which the cell becomes more reduced than in the normal, resting state. This may occur in hypoxia and also in several diseases in which a small but persistent generation of oxidants results in a hormetic overexpression of antioxidant enzymes that leads to a reduction in cell compartments. This is the case of Alzheimer's disease. Individuals at high risk of Alzheimer's (because they carry the ApoE4 allele…
Early reductive stress and late onset overexpression of antioxidant enzymes in experimental myocardial infarction.
2020
Reductive stress is defined as a pathophysiological situation in which the cell becomes more reduced than in the normal, resting state. It represents a disturbance in the redox state that is harmful to biological systems. Our aim was to study the occurrence of reductive stress in the early phases of experimental myocardial infarction and to determine the mechanisms leading to such stress using a swine model. During the ischemic period, we found a decrease in the oxidized to reduced glutathione ratio (GSSG/GSH) (0.7-0.3), in the lactate to pyruvate ratio (42.7-132.4), in protein glutathionylation (111.8-96.1), and in p38 phosphorylation (0.9-0.4). This was accompanied by a significant increa…
Reduced firing rates of pyramidal cells in frontal cortex of APP/PS1 can be restored by acute treatment with levetiracetam
2019
AbstractIn recent years aberrant neural oscillations in various cortical areas have emerged as a common physiological hallmark across mouse models of amyloid pathology and patients with Alzheimer’s disease. However, much less is known about the underlying effect of amyloid pathology on single cell activity. Here, we used high density silicon probe recordings from frontal cortex area of 9 months old APP/PS1 mice to show that resting state Local Field Potential (LFP) power in the theta and beta band is increased in transgenic animals, while single cell firing rates, specifically of putative pyramidal cells, are significantly reduced. At the same time, these sparsely firing pyramidal cells pha…
Cognitive variability in bipolar I disorder: A cluster-analytic approach informed by resting-state data
2019
Abstract Background While the presence of cognitive performance deficits in bipolar disorder I (BD-I) is well established, there is no consensus about which cognitive abilities are affected. Heterogeneous phenotypes displayed in BD-I further suggest the existence of subgroups among the disorder. The present study sought to identify different cognitive profiles among BD-I patients as well as potentially underlying neuronal network changes. Methods 54 euthymic BD-I patients underwent cognitive testing and resting state neuroimaging. Hierarchical cluster-analysis was performed on executive function scores of bipolar patients. The derived clusters were compared against 54 age-, gender- and IQ-m…
Correlation of cerebral blood flow and MCA flow velocity measured in healthy volunteers during acetazolamide and CO2 stimulation
1995
Abstract The assessment of the cerebrovascular reserve capacity (RC) has become a widely used tool in the management of cerebrovascular disease. Discrepancies become obvious, however, if results obtained with different methods are compared. Aim of the present study, therefore, was to compare blood velocity and cerebral perfusion data in the same group of healthy test persons. In 32 volunteers regional cerebral blood flow (rCBF) was measured with the 133 Xe-inhalation method. F1 as grey matter flow and the initial slope index (ISI) were computed. Simultaneously flow velocity in the middle cerebral artery (V MCA ) was assessed by transcranial Doppler sonography (TCD). Measurements were perfor…
Complex network analysis of resting-state fMRI of the brain.
2016
Due to the fact that the brain activity hardly ever diminishes in healthy individuals, analysis of resting state functionality of the brain seems pertinent. Various resting state networks are active inside the idle brain at any time. Based on various neuro-imaging studies, it is understood that various structurally distant regions of the brain could be functionally connected. Regions of the brain, that are functionally connected, during rest constitutes to the resting state network. In the present study, we employed the complex network measures to estimate the presence of community structures within a network. Such estimate is named as modularity. Instead of using a traditional correlation …
Resting-State Functional Connectome in Patients with Brain Tumors Before and After Surgical Resection
2020
Purpose: High-grade glioma surgery has evolved around the principal belief that a safe maximal tumor resection improves symptoms, quality of life, and survival. Mapping brain function has been recently improved by resting-state functional magnetic resonance imaging (rest-fMRI), a novel imaging technique that explores networks connectivity at “rest.” Methods: This prospective study analyzed 10 patients with high-grade glioma in whom rest-fMRI connectivity was assessed both in single-subject and in group analysis before and after surgery. Seed-based functional connectivity analysis was performed with CONN toolbox. Network identification focused on 8 major functional connectivity networks. A v…
Spontaneous brain activity and EEG microstates. A novel EEG/fMRI analysis approach to explore resting-state networks.
2009
The brain is active even in the absence of explicit input or output as demonstrated from electrophysiological as well as imaging studies. Using a combined approach we measured spontaneous fluctuations in the blood oxygen level dependent (BOLD) signal along with electroencephalography (EEG) in eleven healthy subjects during relaxed wakefulness (eyes closed). In contrast to other studies which used the EEG frequency information to guide the functional MRI (fMRI) analysis, we opted for transient EEG events, which identify and quantify brain electric microstates as time epochs with quasi-stable field topography. We then used this microstate information as regressors for the BOLD fluctuations. S…