Power Of Alpha Rhythm Research Articles

PROGNOSTIC ROLE OF EEG INDICATORS FOR CHANGES IN COGNITIVE PERFORMANCE IN PATIENTS IN THE EARLY AND LONG-TERM POSTOPERATIVE PERIODS OF CORONARY ARTERY BYPASS GRAFTING

Aim. To study the prognostic role of background EEG activity indicators recorded in patients in the preoperative period of coronary artery bypass grafting (CABG) for the development of cognitive impairment in the early and late postoperative periods. Methods. A total of 85 patients with coronary artery disease (CAD) who underwent CABG were included in the study. Before CABG (3-5 days) all neuropsychological testing and EEG studies were performed, at the 7-10th days and 1 year after CABG only neuropsychological testing. EEG predictors of early (n = 85) and long-term (n = 65) postoperative cognitive dysfunction were detected using the method of multiple linear regression. Results. EEG predictors of deterioration of cognitive status in the early postoperative period of CABG were basic higher values of theta-rhythm power in the posterior regions of the cortex of both hemispheres with closed and open eyes. Whereas higher preoperative parameters of beta2-rhythm biopotentials in the left frontal areas with eyes open and lower alpha-rhythm power in the left occipital parts of the cerebral cortex with eyes closed were associated with long-term postoperative cognitive dysfunction. Conclusion. associations of preoperative eeg indicators with deteriorations of cognitive status in the early and longterm postoperative periods of cabg were revealed.

Quantitative electrophysiological pattern of neurodegeneration in encephalopathies of various origin

Electrophysiological characteristics of patients with encephalopathy of different etiology are presented. Pathogenic mechanisms affecting the electroencephalographic pattern and quantitative components of electroencephalogram are discussed. The aim of the study was to determine a universal quantitative electrophysiological criterion for the evaluation of neurodegenerative changes in the brain of patients with encephalopathy. We analyzed the data of anamnesis, neurological examination, laboratory tests and electroencephalograms from 389 patients with encephalopathy of post-traumatic, infectious, vascular and mixed etiology. Spectral analysis of electroencephalograms was performed and the values of relative quantitative electrophysiological criterion - the ratio of spectral power in the alpha/theta ranges at rest and during the test with hyperventilation were counted. The ratio of spectral power in the alpha/theta ranges was the lowest in patients of older age group and low - in patients with encephalopathy of infectious etiology. The ratio of the spectral power in the alpha-theta ranges in patients with post-traumatic encephalopathy was significantly different depending on the severity of the traumatic brain injury - mild or moderate/severe. We studied the possibilities of practical application of selected electrophysiological criterion - the ratio of spectral power of rhythms in the alpha-theta ranges. We counted this criterion in 150 patients with encephalopathy for the effectiveness evaluation of the neuroprotective therapy with сortexin. The chosen electrophysiological criterion had proved its effectiveness in therapy monitoring in patients with encephalopathy. In this article we demonstrated the advantages of additional neuroprotective therapy with сortexin. Increase in spectral power of alpha rhythm and decrease in spectral power of slow-wave components in the electroencephalographic pattern characterizes successful neuroprotective therapy with neuropeptides, such as сortexin.

Towards multilevel mental stress assessment using SVM with ECOC: an EEG approach.

Mental stress has been identified as one of the major contributing factors that leads to various diseases such as heart attack, depression, and stroke. To avoid this, stress quantification is important for clinical intervention and disease prevention. This study aims to investigate the feasibility of exploiting electroencephalography (EEG) signals to discriminate between different stress levels. We propose a new assessment protocol whereby the stress level is represented by the complexity of mental arithmetic (MA) task for example, at three levels of difficulty, and the stressors are time pressure and negative feedback. Using 18-male subjects, the experimental results showed that there were significant differences in EEG response between the control and stress conditions at different levels of MA task with p values <0.001. Furthermore, we found a significant reduction in alpha rhythm power from one stress level to another level, p values <0.05. In comparison, results from self-reporting questionnaire NASA-TLX approach showed no significant differences between stress levels. In addition, we developed a discriminant analysis method based on multiclass support vector machine (SVM) with error-correcting output code (ECOC). Different stress levels were detected with an average classification accuracy of 94.79%. The lateral index (LI) results further showed dominant right prefrontal cortex (PFC) to mental stress (reduced alpha rhythm). The study demonstrated the feasibility of using EEG in classifying multilevel mental stress and reported alpha rhythm power at right prefrontal cortex as a suitable index.

EEG correlates of working memory performance in females

BackgroundThe study investigates oscillatory brain activity during working memory (WM) tasks. The tasks employed varied in two dimensions. First, they differed in complexity from average to highly demanding. Second, we used two types of tasks, which required either only retention of stimulus set or retention and manipulation of the content. We expected to reveal EEG correlates of temporary storage and central executive components of WM and to assess their contribution to individual differences.ResultsGenerally, as compared with the retention condition, manipulation of stimuli in WM was associated with distributed suppression of alpha1 activity and with the increase of the midline theta activity. Load and task dependent decrement of beta1 power was found during task performance. Beta2 power increased with the increasing WM load and did not significantly depend on the type of the task. At the level of individual differences, we found that the high performance (HP) group was characterized by higher alpha rhythm power. The HP group demonstrated task-related increment of theta power in the left anterior area and a gradual increase of theta power at midline area. In contrast, the low performance (LP) group exhibited a drop of theta power in the most challenging condition. HP group was also characterized by stronger desynchronization of beta1 rhythm over the left posterior area in the manipulation condition. In this condition, beta2 power increased in the HP group over anterior areas, but in the LP group over posterior areas.ConclusionsWM performance is accompanied by changes in EEG in a broad frequency range from theta to higher beta bands. The most pronounced differences in oscillatory activity between individuals with high and low WM performance can be observed in the most challenging WM task.

ФОРМУВАННЯ ДОВІЛЬНОЇ УВАГИ У ЧОЛОВІКІВ ТА ЖІНОК ПРИ ВИКОНАННІ ЗАВДАНЬ ІЗ ВИСОКИМ КОГНІТИВНИМ НАВАНТАЖЕННЯМ

The differences in brain mechanisms that underlie the switch between involuntary and voluntary attention associated with gender were investigated. We compared reaction time, the number of errors and the electrical activity of the brain during the Emotional Stroop test on the background of visual content that contained affective images when presenting stimuli through a dominant and non-dominant eye in 20 men and 20 women. The model of significant cognitive load was created, when it is quite difficult to correctly respond to the relevant characteristics of the stimulus. Different patterns of brain activity have been found: in women, this task is accompanied by an increase in spectral power in the theta range of the predominantly left hemisphere; in men, the power of alpha rhythm in the parietal-occipital associative cortex decreases with the local increase of theta rhythm in the posterior-frontal areas and beta-rhythm in left prefrontal zone. Under the conditions of high cognitive load created by the distracting visual content and the perception of visual stimuli through the non-dominant eye, the brain mechanisms of voluntary attention provide a more thorough analysis of the relevant stimuli in women that is seen in accurate responses over a longer period in comparison with men.

Alpha Wavelet Power as a Biomarker of Antidepressant Treatment Response in Bipolar Depression.

There is mounting evidence of a link between the properties of electroencephalograms (EEGs) of depressive patients and the outcome of pharmacotherapy. The goal of this study was to develop an EEG biomarker of antidepressant treatment response which would require only a single EEG measurement. We recorded resting 21-channel EEG in 17 in-patients suffering from bipolar depression in eyes-closed and eyes-open conditions. The EEG measurement was performed at the end of a short washout period which followed previous unsuccessful pharmacotherapy. We calculated the normalized wavelet power of alpha rhythm using two referential montages and an average reference montage. The difference in the normalized alpha wavelet power between 10 responders and 7 non-responders was most strongly pronounced in link mastoid montage in the eyes-closed condition. In particular, in the occipital (O1, O2, Oz) channels the wavelet power of responders was up to 84 % higher than that of non-responders. Using a novel classification algorithm we were able to correctly predict the outcome of treatment with 90 % sensitivity and 100 % specificity. The proposed biomarker requires only a single EEG measurement and consequently is intrinsically different from biomarkers which exploit the changes in prefrontal EEG induced by pharmacotherapy over a given time.

Сlinical and physiological characteristics and therapy asthenic disorders in adolescents girls

To study clinical and psychophysiological characteristics of asthenic disorders in adolescent girls in the aspect of treatment efficacy of cortexin. Seventy-five women, aged 14-17 years, who were diagnosed with neurasthenia (ICD-10 F.48.0), were examined. Conventional neurological examination, a 10-point Visual Analogue Scale, the Multidimensional Fatigue Inventory (MFI-20), the A.M. Vein questionnaire, the Spielberger-Khanin questionnaire and EEG were used. The high level of anxiety resulted in the development of autonomic symptoms and cephalgia. The EEG study showed that women with neurasthenia were characterized by lower alpha-rhythm power in the occipital sites compared with healthy peers. Treatment with cortexin improved patient's condition in 80% of cases that was supported by the positive EG dynamics.

Resting state brain dynamics and its transients: a combined TMS-EEG study.

The brain at rest exhibits a spatio-temporally rich dynamics which adheres to systematic behaviours that persist in task paradigms but appear altered in disease. Despite this hypothesis, many rest state paradigms do not act directly upon the rest state and therefore cannot confirm hypotheses about its mechanisms. To address this challenge, we combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to study brain’s relaxation toward rest following a transient perturbation. Specifically, TMS targeted either the medial prefrontal cortex (MPFC), i.e. part of the Default Mode Network (DMN) or the superior parietal lobule (SPL), involved in the Dorsal Attention Network. TMS was triggered by a given brain state, namely an increase in occipital alpha rhythm power. Following the initial TMS-Evoked Potential, TMS at MPFC enhances the induced occipital alpha rhythm, called Event Related Synchronisation, with a longer transient lifetime than TMS at SPL, and a higher amplitude. Our findings show a strong coupling between MPFC and the occipital alpha power. Although the rest state is organized around a core of resting state networks, the DMN functionally takes a special role among these resting state networks.

Long-term correlation of the electrocorticogram as a bioindicator of brain exposure to ionizing radiation.

Understanding the effects of radiation and its possible influence on the nervous system are of great clinical interest. However, there have been few electrophysiological studies on brain activity after exposure to ionizing radiation (IR). A new methodological approach regarding the assessment of the possible effects of IR on brain activity is the use of linear and nonlinear mathematical methods in the analysis of complex time series, such as brain oscillations measured using the electrocorticogram (ECoG). The objective of this study was to use linear and nonlinear mathematical methods as biomarkers of gamma radiation regarding cortical electrical activity. Adult Wistar rats were divided into 3 groups: 1 control and 2 irradiated groups, evaluated at 24 h (IR24) and 90 days (IR90) after exposure to 18 Gy of gamma radiation from a cobalt-60 radiotherapy source. The ECoG was analyzed using power spectrum methods for the calculation of the power of delta, theta, alpha and beta rhythms and by means of the α-exponent of the detrended fluctuation analysis (DFA). Using both mathematical methods it was possible to identify changes in the ECoG, and to identify significant changes in the pattern of the recording at 24 h after irradiation. Some of these changes were persistent at 90 days after exposure to IR. In particular, the theta wave using the two methods showed higher sensitivity than other waves, suggesting that it is a possible biomarker of exposure to IR.

Relating Alpha Power and Phase to Population Firing and Hemodynamic Activity Using a Thalamo-cortical Neural Mass Model.

Oscillations are ubiquitous phenomena in the animal and human brain. Among them, the alpha rhythm in human EEG is one of the most prominent examples. However, its precise mechanisms of generation are still poorly understood. It was mainly this lack of knowledge that motivated a number of simultaneous electroencephalography (EEG) – functional magnetic resonance imaging (fMRI) studies. This approach revealed how oscillatory neuronal signatures such as the alpha rhythm are paralleled by changes of the blood oxygenation level dependent (BOLD) signal. Several such studies revealed a negative correlation between the alpha rhythm and the hemodynamic BOLD signal in visual cortex and a positive correlation in the thalamus. In this study we explore the potential generative mechanisms that lead to those observations. We use a bursting capable Stefanescu-Jirsa 3D (SJ3D) neural-mass model that reproduces a wide repertoire of prominent features of local neuronal-population dynamics. We construct a thalamo-cortical network of coupled SJ3D nodes considering excitatory and inhibitory directed connections. The model suggests that an inverse correlation between cortical multi-unit activity, i.e. the firing of neuronal populations, and narrow band local field potential oscillations in the alpha band underlies the empirically observed negative correlation between alpha-rhythm power and fMRI signal in visual cortex. Furthermore the model suggests that the interplay between tonic and bursting mode in thalamus and cortex is critical for this relation. This demonstrates how biophysically meaningful modelling can generate precise and testable hypotheses about the underpinnings of large-scale neuroimaging signals.

Prestimulus EEG alpha oscillations modulate task-related fMRI BOLD responses to auditory stimuli

EEG alpha-band activity is generally thought to represent an inhibitory state related to decreased attention and play a role in suppression of task-irrelevant stimulus processing, but a competing hypothesis suggests an active role in processing task-relevant information — one in which phase dynamics are involved. Here we used simultaneous EEG–fMRI and a whole-brain analysis to investigate the effects of prestimulus alpha activity on the event-related BOLD response during an auditory oddball task. We separately investigated the effects of the posterior alpha rhythm's power and phase on activity related to task-relevant stimulus processing and also investigated higher-level decision-related processing. We found stronger decision-related BOLD activity in areas late in the processing stream when subjects were in the high alpha power state prior to stimulus onset, but did not detect any effect in primary sensory regions. Our phase analysis revealed correlates in the bilateral thalamus, providing support for a thalamo–cortical loop in attentional modulations and suggesting that the cortical alpha rhythm acts as a cyclic modulator of task-related responses very early in the processing stream. Our results help to reconcile the competing inhibition and active-processing hypotheses for ongoing alpha oscillations and begin to tease apart the distinct roles and mechanisms underlying their power and phase.

Spectral Power of Eeg Alpha Rhythm During Resting State in Children with Autistic Spectrum Disorder

Introduction There are some indications on the importance of focusing on resting state EEG and its possible links to cognitive symptoms in individuals with autistic spectrum disorder (ASD). Evidence points to disrupted neural oscillations inthese individuals, which can be seen in EEG power. Objectives Since EEG studies on younger ages of children with ASD are sparse as well as contradictory, we have included a wide age sample of children with ASD, in order to examine possible electrophysiological pathological markers of resting state brain activity. At the cognitive level, resting state is associated with fluctuations of attention from internalized to externalized states of mind. Aims in the current study, we have examined whether differences exist in spectral power of resting state within the alpha band, as it is more directly linked to attentional processes. Methods We have extracted spectral power from resting state EEG within the alpha band over the frontal and sensorimotor regions, in a sample of 45 children with ASD, compared to an age and gender matched typical sample. Results preliminary results point to group differences in EEG power when lower alpha band is considered, both in frontal and sensorimotor brain areas in a wide age sample, between children with ASD and the typical population. Conclusions Results are discussed in light of EEG measures which could be used as diagnostic tools in clinical practice. Importance of mapping the link between attentional deficits and EEG measures in ASD is highlighted.

Prestimulus Alpha Oscillations as an Index of Increased Cognitive Control Under the Auditory Condensation Task

Attentional lapses are usually viewed as a result of deterioration in cognitive control. Current theories suggest that deterioration in the cognitive control may be related to an increase in alpha rhythm power, although it is not clear whether this notion can be generalized outside of the visual task modality. In the current study power of prestimulus alpha-band oscillations was analyzed during performance of the modified auditory condensation task, which creates high attentional load. Prestimulus lower alpha-band power was found to decrease before erroneous responses, which can be viewed as attentional lapses related to decreased cognitive control, compared with correct responses. Prestimulus lower alpha-band power also gradually increased within continuous sequences of distractor stimuli separating adjacent target stimuli, thus reflecting gradual increase in the level of cognitive control mirroring increasing expectancy of the target stimuli. These findings demonstrate that the relation of alpha power to cognitive control level critically depends on the experimental task modality, and under conditions of the auditory attentional task higher alpha power may be an index of increased rather than decreased level of cognitive control.

Short-Term Kinesthetic Training for Sensorimotor Rhythms: Effects in Experts and Amateurs

ABSTRACTThe authors’ aim was to examine whether short-term kinesthetic training affects the level of sensorimotor rhythm (SMR) in different frequency band: alpha (8–12 Hz), lower beta (12.5–16 Hz) and beta (16.5–20 Hz) during the execution of a motor imagery task of closing and opening the right and the left hand by experts (jugglers, practicing similar exercises on an everyday basis) and amateurs (individuals not practicing any sports). It was found that the performance of short kinesthetic training increases the power of alpha rhythm when executing imagery tasks only in the group of amateurs. Therefore, kinesthetic training may be successfully used as a method increasing the vividness of motor imagery, for example, in tasks involving the control of brain–computer interfaces based on SMR.

P.1.i.011 The effects of the VRK2 (rs2312147) gene on white matter connectivity in patients with schizophrenia

High power of pre-stimulus cortical alpha rhythms (about 8–12 Hz) underlies conscious perception in normal subjects. Here we tested the hypothesis that these rhythms are abnormal in persistent vegetative state (PVS) patients, who are awake but not aware of self and environment.Clinical and resting-state, eyes-closed electroencephalographic (EEG) data were taken from a clinical archive. These data were recorded in 50 PVS subjects (level of cognitive functioning – LCF score: I–II) and in 30 cognitively normal subjects. Rhythms of interest were delta (2–4 Hz), theta (4–8 Hz), alpha 1 (8–10.5 Hz), alpha 2 (10.5–13 Hz), beta 1 (13–20 Hz), and beta 2 (20–30 Hz). Cortical sources were estimated by low-resolution electromagnetic tomography (LORETA). Based on LCF score at 3-months follow-up, PVS patients were retrospectively divided into three groups: 30 subjects who did not recover (NON-REC patients; follow-up LCF: I–II), 8 subjects classified as minimally conscious state patients (MCS patients; follow-up LCF: III–IV), and 12 subjects who recovered (REC patients; follow-up LCF: V–VIII).Occipital source power of alpha 1 and alpha 2 was high in normal subjects, low in REC patients, and practically null in NON-REC patients. A Cox regression analysis showed that the power of alpha source predicted the rate of the follow up recovery, namely the higher its power, the higher the chance to recover consciousness. Furthermore, the MCS patients showed intermediate values of occipital alpha source power between REC and NON-REC patients.These results suggest that cortical sources of alpha rhythms are related to the chance of recovery at a 3-months follow-up in patients in persistent vegetative state.Cortical sources of resting alpha rhythms might predict recovery in PVS patients.

Electroencephalographic effects of ketamine on power, cross-frequency coupling, and connectivity in the alpha bandwidth.

Recent studies of propofol-induced unconsciousness have identified characteristic properties of electroencephalographic alpha rhythms that may be mediated by drug activity at γ-aminobutyric acid (GABA) receptors in the thalamus. However, the effect of ketamine (a primarily non-GABAergic anesthetic drug) on alpha oscillations has not been systematically evaluated. We analyzed the electroencephalogram of 28 surgical patients during consciousness and ketamine-induced unconsciousness with a focus on frontal power, frontal cross-frequency coupling, frontal-parietal functional connectivity (measured by coherence and phase lag index), and frontal-to-parietal directional connectivity (measured by directed phase lag index) in the alpha bandwidth. Unlike past studies of propofol, ketamine-induced unconsciousness was not associated with increases in the power of frontal alpha rhythms, characteristic cross-frequency coupling patterns of frontal alpha power and slow-oscillation phase, or decreases in coherence in the alpha bandwidth. Like past studies of propofol using undirected and directed phase lag index, ketamine reduced frontal-parietal (functional) and frontal-to-parietal (directional) connectivity in the alpha bandwidth. These results suggest that directional connectivity changes in the alpha bandwidth may be state-related markers of unconsciousness induced by both GABAergic and non-GABAergic anesthetics.

The neurofeedback course using of high skilled gymnasts at competitive period

Strizhkova, O., Cherapkina, L. & Strizhkova, T. (2014). The neurofeedback course using of high skilled gymnasts at competitive period. J. Hum. Sport Exerc., 9(Proc1), pp.S561-S569. The research was carried out with 28 high skilled gymnasts (15 ‐ main group, 13 ‐ control group) allowed to define the neurofeedback influence on the functional condition of sportswomen in competitive period. The neurofeedback course promotes improvement of rapidity of complex coordinating motions learning, vestibular stability and self-estimation of functional condition. Also it conducts the alpha-rhythm power increasing at left hemisphere. The neurofeedback course efficiency is defined by index of change of course average alpha-rhythm power with 100% prognostic accuracy. The attention switching, attention stability and self-estimation of sleep and memory are predictors of neurofeedback course successfulness. Key words: EFFICIENCY OF TRAINING, SUCCESSFULNESS OF TRAINING, CEREBRUM BIOELECTRIC ACTIVITY, PREDICTORS OF EFFICIENCY AND SUCCESSFULNESS.

DEANOL ACEGLUMATE IN NEURASTHENIA TREATMENT IN ADOLESCENTS WITH SCHOOL DISADAPTATION

Aim: to study clinical manifestation of neurasthenia in adolescents with school disadaptation and to assess efficacy of deanol aceglumate in treatment of this disorder. Patients and methods: 64 adolescents aged from 14 to 17 years with neurasthenia were included into the study. Control group consisted of 64 practically healthy adolescents. Diagnostic methods: subjective scale for asthenia assessment (MFI-20), visual analogue scale for asthenia manifestations assessment (10-points scale), C. D. Spielberger’s state-trait anxiety test, vegetologic examination with A. M. Vein’s questionnaire, psychophysiological investigation with TOVA (Test of Variables of Attention), quantitative electroencephalography. Results: vegetative dysfunction, decrease of attention level and reaction speed, as well as increased level of reactive anxiety (reliably higher than in control group of healthy participants) was revealed. The results of quantitative electroencephalography demonstrated significant decrease of alpha-rhythm spectrum power in occipital leads in comparison with respective characteristic in the control group. The results of clinical and psychological studies, performed after the treatment course, showed high clinical efficacy of deanol aceglumate in this disorder in adolescents (the improvement was achieved in 44 (68,8%) of patients). Conclusions: deanol aceglumate in treatment of asthenic disorders in adolescents with school disadaptation is characterized by high efficacy. Due to absence of its influence on anxiety level, combination of this medicine with nonbenzodiazepine anxiolytics can be suggested to increase the efficacy of the treatment.

Mini-Mental State Examination in patients with hepatic encephalopathy and liver cirrhosis: a prospective, quantified electroencephalography study

BackgroundMini-Mental State Examination (MMSE) is one of the most commonly used methods in the assessment of cognitive mental status. MMSE has been used in hepatology but its usefulness in the evaluation of hepatic encephalopathy (HE) has never been properly assessed. The aim of the study was to investigate the value of MMSE in detection of HE in patients with cirrhosis.MethodsOne hundred and one consecutive patients with liver cirrhosis underwent neurological examination, MMSE and electroencephalography (EEG). Spectral analysis of EEG was done with calculation of mean dominant frequency (MDF) and relative power of delta, theta, alpha and beta rhythms. Minimal HE was diagnosed in patients with normal neurological status and alterations in spectral EEG. Statistical analysis included Fisher’s exact and Anova analysis. Categorical data were compared using Levene’s test for equality of variances. Correlation-coefficient analysis was performed by the Pearson’s r or Z-test, as needed. Tests performance was assessed by the calculating the area under the ROC curve (AUC) and evaluating its difference from reference area (AUC=0.5). A p value <0.05 was considered statistically significant.ResultsOvert HE was identified in 49 (48.5%) and minimal HE in 22 (21.8%) patients. Although there were significant correlations between both severity of liver disease (Child-Pugh classification), overt HE (West-Haven criteria) and various MMSE items, MDF showed no correlation with any of MMSE items as well as MMSE summary score. MMSE (score and items) did not discriminate patients without HE and minimal HE. The only significant differences between patients without HE and with overt HE were seen in respect of MMSE score (p<0.02), orientation to place (p<0.003), repetition (p<0.01) and complex commands-understanding (p<0.02). Test performance analysis has shown that MMSE has no value as a prediction method in determining minimal HE and in respect of overt HE has a sensitivity of 63% and specificity of 52% by a cut-off level at 27.5 points to diagnose overt HE.ConclusionsIn conclusion, although MMSE score and single items are altered in patients with overt HE, MMSE has no value in the assessment of minimal HE. Because MMSE could be impaired in several cognitive dysfunctions, more specific test should be used for measuring HE.

Cortical neural synchronization mechanisms in Alzheimer's disease as revealed by resting state EEG rhythms: A window on cholinergic function?

Current pharmacological treatments of Alzheimer's disease (AD) include the use of acetylcholinesterase inhibitors (AChEIs), based on the cholinergic hypothesis of the disease. However, converging evidence has shown a strong and unpredictable inter-individual variation in response to AChEI treatment. This motivates a better understanding of the neurophysiological role played by cholinergic neurophysiological systems in subjects with prodromal and overt AD. The present Consortium has probed neurophysiological mechanisms of cortical neural synchronization in pathological aging as revealed by an advanced spectral analysis of resting state eyes-closed electroencephalographic (EEG) rhythms in groups of normal elderly (Nold), amnesic mild cognitive impairment (MCI), cerebrovascular dementia (CVD), Parkinson disease with dementia (PDD), covert hepatic encephalopathy (CHE), and AD subjects. (1) dominant alpha frequencies (8–10 Hz) of EEG rhythms were specifically abnormal in the AD group when compared to the Nold, MCI, CVD, PPD, and CHE groups; (2) delta (2–4 Hz) and alpha rhythms were related to attention and global cognitive status in both MCI and AD groups; (3) power and functional coupling of alpha rhythms were related to white-matter lesions along the cholinergic tracts in the MCI group; (4) long-term (1 year) cholinergic therapy was just able to slow the derangement of alpha rhythms in the AD group. These findings suggest that resting state EEG rhythms may reflect the dysfunction of cholinergic neuromodulation of cortical neural synchronization in the MCI and in the AD group. Future research will have to evaluate the clinical impact of this methodological approach in individual patients.