Search results for "fMRI"

Assessing sensory versus optogenetic network activation by combining (o)fMRI with optical Ca2+ recordings

2016

Encoding of sensory inputs in the cortex is characterized by sparse neuronal network activation. Optogenetic stimulation has previously been combined with fMRI (ofMRI) to probe functional networks. However, for a quantitative optogenetic probing of sensory-driven sparse network activation, the level of similarity between sensory and optogenetic network activation needs to be explored. Here, we complement ofMRI with optic fiber-based population Ca2+ recordings for a region-specific readout of neuronal spiking activity in rat brain. Comparing Ca2+ responses to the blood oxygenation level-dependent signal upon sensory stimulation with increasing frequencies showed adaptation of Ca2+ transient…

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…

Author response: Cortex-wide BOLD fMRI activity reflects locally-recorded slow oscillation-associated calcium waves

2017

Cortex-wide BOLD fMRI activity reflects locally-recorded slow oscillation-associated calcium waves.

2017

When a person is in a deep non-dreaming sleep, neurons in their brain alternate slowly between periods of silence and periods of activity. This gives rise to low-frequency brain rhythms called slow waves, which are thought to help stabilize memories. Slow wave activity can be detected on multiple scales, from the pattern of electrical impulses sent by an individual neuron to the collective activity of the brain’s entire outer layer, the cortex. But does slow wave activity in an individual group of neurons in the cortex affect the activity of the rest of the brain? To find out, Schwalm, Schmid, Wachsmuth et al. took advantage of the fact that slow waves also occur under general anesthesia, a…

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…

Music style not only modulates the auditory cortex, but also motor related areas

2021

The neuroscience of music has recently attracted significant attention, but the effect of music style on the activation of auditory-motor regions has not been explored. The aim of the present study is to analyze the differences in brain activity during passive listening to non-vocal excerpts of four different music genres (classical, reggaeton, electronic and folk). A functional magnetic resonance imaging (fMRI) experiment was performed. Twenty-eight participants with no musical training were included in the study. They had to passively listen to music excerpts of the above genres during fMRI acquisition. Imaging analysis was performed at the whole-brain-level and in auditory-motor regions …

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…

Dynamic Functional Connectivity Captures Individuals’ Unique Brain Signatures

2020

Recent neuroimaging evidence suggest that there exists a unique individual-specific functional connectivity (FC) pattern consistent across tasks. The objective of our study is to utilize FC patterns to identify an individual using a supervised machine learning approach. To this end, we use two previously published data sets that comprises resting-state and task-based fMRI responses. We use static FC measures as input to a linear classifier to evaluate its performance. We additionally extend this analysis to capture dynamic FC using two approaches: the common sliding window approach and the more recent phase synchrony-based measure. We found that the classification models using dynamic FC pa…