Search results for "Alpha Rhythm"
showing 10 items of 18 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…
Adaptive frequency decomposition of EEG with subsequent expert system analysis.
2001
We present a hybrid system for automatic analysis of clinical routine EEG, comprising a spectral analysis and an expert system. EEG raw data are transformed into the time-frequency domain by the so-called adaptive frequency decomposition. The resulting frequency components are converted into pseudo-linguistic facts via fuzzification. Finally, an expert system applies symbolic rules formulated by the neurologist to evaluate the extracted EEG features. The system detects artefacts, describes alpha rhythm by frequency, amplitude, and stability and after artefact rejection detects pathologic slow activity. All results are displayed as linguistic terms, numerical values and maps of temporal exte…
Anterior limbic alpha-like activity: a low resolution electromagnetic tomography study with lorazepam challenge
2005
Summary Objective To verify findings of an independently regulated anterior limbic alpha band source. Methods In a randomised cross-over study, the spontaneous EEG was recorded in nine healthy subjects after i.v. lorazepam or placebo. Intracerebral current densities within classical frequency bands were estimated with low resolution electromagnetic tomography [LORETA] and compared between groups with t -statistical parametric mapping [SPM{ t }]. A region-of-interest [ROI] based method was used to compare frontal and occipital alpha band activity changes. Results Irrespective of treatment group, local maxima of alpha band power were localised both in the occipital lobe, Brodman area [BA] 18,…
Lack of effects of low frequency repetitive transcranial magnetic stimulation on alpha rhythm phase synchronization in migraine patients
2010
The study aimed to test the modulation induced by 1 Hz repetitive Transcranial Magnetic Stimulation (rTMS) of the occipital cortex on the alpha phase synchronization under repetitive flash stimuli in 15 migraine without aura patients compared to 10 controls. The EEG was recorded by 7 channels, while flash stimuli were delivered at 9, 18, 21 and 24 Hz in basal, rTMS (15 min of 1 Hz stimulation of the occipital cortex) and sham conditions. Migraine patients displayed increased alpha-band phase synchronization under visual stimulation, while an overall desynchronizing effect was evident in controls. The rTMS resulted in a slight increase of synchronization index in migraine patients, which did…
Limbic activity in slow wave sleep in a healthy subject with alpha–delta sleep
2001
All-night electroencephalographic (EEG) activity was recorded in a healthy subject with known alpha-delta sleep. Recordings were made from all 19 of the 10/20 system electrode sites, and low resolution electromagnetic tomography (LORETA) was used to estimate intracerebral current densities. Sleep stages were compared within classical frequency bands by statistical parametric mapping (SPM). With the onset of sleep, occipital alpha abated. With increasing depth of sleep, alpha power increased in a region comprising the left frontal lobe, the anterior and parietal cingulum, and the anterior and medial right front lobe. In slow wave sleep (SWS), frontal alpha power was much greater than in wake…
Revisiting mu suppression in autism spectrum disorder
2014
Two aspects of the EEG literature lead us to revisit mu suppression in Autism Spectrum Disorder (ASD). First and despite the fact that the mu rhythm can be functionally segregated in two discrete sub-bands, 8-10 Hz and 10-12/13 Hz, mu-suppression in ASD has been analyzed as a homogeneous phenomenon covering the 8-13 Hz frequency. Second and although alpha-like activity is usually found across the entire scalp, ASD studies of action observation have focused on the central electrodes (C3/C4). The present study was aimed at testing on the whole brain the hypothesis of a functional dissociation of mu and alpha responses to the observation of human actions in ASD according to bandwidths. Electro…
Prismatic Adaptation Modulates Oscillatory EEG Correlates of Motor Preparation but Not Visual Attention in Healthy Participants.
2017
Prismatic adaption (PA) has been proposed as a tool to induce neural plasticity and is used to help neglect rehabilitation. It leads to a recalibration of visuomotor coordination during pointing as well as to aftereffects on a number of sensorimotor and attention tasks, but whether these effects originate at a motor or attentional level remains a matter of debate. Our aim was to further characterize PA aftereffects by using an approach that allows distinguishing between effects on attentional and motor processes. We recorded EEG in healthy human participants (9 females and 7 males) while performing a new double step, anticipatory attention/motor preparation paradigm before and after adaptat…
Gesture's body orientation modulates the N400 for visual sentences primed by gestures
2020
Abstract Body orientation of gesture entails social‐communicative intention, and may thus influence how gestures are perceived and comprehended together with auditory speech during face‐to‐face communication. To date, despite the emergence of neuroscientific literature on the role of body orientation on hand action perception, limited studies have directly investigated the role of body orientation in the interaction between gesture and language. To address this research question, we carried out an electroencephalography (EEG) experiment presenting to participants (n = 21) videos of frontal and lateral communicative hand gestures of 5 s (e.g., raising a hand), followed by visually presented …
Electroencephalographic alpha activity modulations induced by breath-holding in apnoea divers and non-divers.
2017
Little is known regarding cortical responses to sustained breath-holding (BH) in expert apnoea divers. The present study therefore investigated electroencephalographic (EEG) alpha activity and asymmetries in apnoea divers (experts) compared to non-divers (novices). EEG of 10 apnoea and 10 non-divers were recorded in the laboratory for either four minutes or for two minutes of BH. Alpha activity and alpha asymmetry (i.e. hemispherical EEG differences) were calculated and compared between expertise level and BH duration. Alpha amplitude in experts significantly decreased at four minutes of BH compared to resting activity, while alpha amplitude significantly decreased in novices only at centro…
The thalamus as the generator and modulator of EEG alpha rhythm: a combined PET/EEG study with lorazepam challenge in humans
2003
Background: Purpose of this study was to investigate the functional relationship between electroencephalographic (EEG) alpha power and cerebral glucose metabolism before and after pharmacological alpha suppression by lorazepam. Methods: Ten healthy male volunteers were examined undergoing two F18-fluorodeoxyglucose (18-FDG) positron emission tomography (PET) scans with simultaneous EEG recording: 1× placebo, 1× lorazepam. EEG power spectra were computed by means of Fourier analysis. The PET data were analyzed using SPM99, and the correlations between metabolism and alpha power were calculated for both conditions. Results: The comparison lorazepam versus placebo revealed reduced glucose meta…