Changes In EEG Activity Research Articles

Nonconvulsive status epilepticus cases arising in connection with cephalosporins

Cephalosporins, particularly cefepime, exert neurotoxic side effects that can lead to status epilepticus. These neurotoxic side effects include myoclonus, dystonic movements, tremor, asterixis, seizure, status epilepticus, encephalopathy, and sometimes coma. Status epilepticus, particularly nonconvulsive status epilepticus (NCSE), is a well-known but unusual complication in patients with altered renal function who were receiving treatment with intravenous cephalosporins, especially cefepime. We reviewed the clinical and electroencephalographic (EEG) characteristics of 7 patients with renal failure who developed consciousness alterations with changes in EEG activity while being treated with cephalosporins. All patients developed renal failure: six patients had chronic renal failure, one patient had acute renal failure, and two patients were administered hemodialysis. Nonconvulsive status epilepticus was observed between 2 and 8 days (average of 5.6 days) after initiation of cephalosporins. Cephalosporins are epileptogenic drugs, especially when used in excessive doses or when renal function is impaired. Critically ill patients with chronic kidney disease are particularly susceptible to cefepime neurotoxicity. Clinical and electrophysiological results of patients guide the diagnosis of NCSE by healthcare providers.

Electrical Changes in Deeper Cortical Structures During Balanced General Anesthesia with the Aim on Inhalation Anesthetics Effects

Abstract There are many theories that attempt to explain the mechanisms of the effects of inhalation anesthetics - from simpler, pursuing individual effects of anesthetics on the level of the ion channels, to more complex that are looking for uniform global changes in brain activity common to several agents. However, we still don’t have satisfactory and adequate conclusions. We examined a sample of 39 patients undergoing thoracic surgery at the Clinic of Thoracic Surgery under general anesthesia (GA) and we registered their electroencephalographic (EEG) signals before and during operation. After induction of GA by intravenous (i.v.), we used inhalation anesthetics to maintain GA. We used sevoflurane (SEV) in 20 patients and desflurane (DES) in 19 patients. Then we obtained the EEG data and processed them through mathematical and statistical analysis, to discover any changes of electrical activity in the brain during thoracic surgery under GA. The era of digital recording EEG and present possibilities of modern computer techniques allow quantitative analysis of obtained data. We performed the analysis with the software LORETA (low resolution brain electromagnetic tomography). It is a relatively new research method, which in a similar way as computed tomography (CT) or magnetic resonance imaging (MRI) displays even deeper brain electrical activity, which is hiddeen for a classical EEG approach. We described the general changes in brain electrical activity of the deeper cortical structures within the traditional frequency bands (d, q, a, b and g) during GA at 5 mm spatial resolution. We have shown that the source of the well-known cortical EEG changes after the effect of used inhalation anesthetics is caused by changes situated in the deeper brain structures, particularly the limbic system. Significant changes occurred in the cingulate gyrus for most of an EEG frequency ranges. When comparing the data of patients anesthetised with SEV and DES we found similar changes within the d and q rhythms and then the global changes of EEG activity followed during GA.

Self-organized dynamical complexity in human wakefulness and sleep: different critical brain-activity feedback for conscious and unconscious states.

Criticality reportedly describes brain dynamics. The main critical feature is the presence of scale-free neural avalanches, whose auto-organization is determined by a critical branching ratio of neural-excitation spreading. Other features, directly associated to second-order phase transitions, are: (i) scale-free-network topology of functional connectivity, stemming from suprathreshold pairwise correlations, superimposable, in waking brain activity, with that of ferromagnets at Curie temperature; (ii) temporal long-range memory associated to renewal intermittency driven by abrupt fluctuations in the order parameters, detectable in human brain via spatially distributed phase or amplitude changes in EEG activity. Herein we study intermittent events, extracted from 29 night EEG recordings, including presleep wakefulness and all phases of sleep, where different levels of mentation and consciousness are present. We show that while critical avalanching is unchanged, at least qualitatively, intermittency and functional connectivity, present during conscious phases (wakefulness and REM sleep), break down during both shallow and deep non-REM sleep. We provide a theory for fragmentation-induced intermittency breakdown and suggest that the main difference between conscious and unconscious states resides in the backwards causation, namely on the constraints that the emerging properties at large scale induce to the lower scales. In particular, while in conscious states this backwards causation induces a critical slowing down, preserving spatiotemporal correlations, in dreamless sleep we see a self-organized maintenance of moduli working in parallel. Critical avalanches are still present, and establish transient auto-organization, whose enhanced fluctuations are able to trigger sleep-protecting mechanisms that reinstate parallel activity. The plausible role of critical avalanches in dreamless sleep is to provide a rapid recovery of consciousness, if stimuli are highly arousing.

EEG Changes Due to Experimentally Induced 3G Mobile Phone Radiation.

The aim of this study was to investigate whether a 15-minute placement of a 3G dialing mobile phone causes direct changes in EEG activity compared to the placement of a sham phone. Furthermore, it was investigated whether placement of the mobile phone on the ear or the heart would result in different outcomes. Thirty-one healthy females participated. All subjects were measured twice: on one of the two days the mobile phone was attached to the ear, the other day to the chest. In this single-blind, cross-over design, assessments in the sham phone condition were conducted directly preceding and following the mobile phone exposure. During each assessment, EEG activity and radiofrequency radiation were recorded jointly. Delta, theta, alpha, slowbeta, fastbeta, and gamma activity was computed. The association between radiation exposure and the EEG was tested using multilevel random regression analyses with radiation as predictor of main interest. Significant radiation effects were found for the alpha, slowbeta, fastbeta, and gamma bands. When analyzed separately, ear location of the phone was associated with significant results, while chest placement was not. The results support the notion that EEG alterations are associated with mobile phone usage and that the effect is dependent on site of placement. Further studies are required to demonstrate the physiological relevance of these findings.

The Mozart Effect: A quantitative EEG study.

The aim of this study is to investigate the influence of Mozart's music on brain activity through spectral analysis of the EEG in young healthy adults (Adults), in healthy elderly (Elderly) and in elderly with Mild Cognitive Impairment (MCI). EEG recording was performed at basal rest conditions and after listening to Mozart's K448 or "Fur Elise" Beethoven's sonatas. After listening to Mozart, an increase of alpha band and median frequency index of background alpha rhythm activity (a pattern of brain wave activity linked to memory, cognition and open mind to problem solving) was observed both in Adults and in Elderly. No changes were observed in MCI. After listening to Beethoven, no changes in EEG activity were detected. This results may be representative of the fact that said Mozart's music is able to "activate" neuronal cortical circuits related to attentive and cognitive functions.

Abstract T P121: Combinations of Fast and Slow Eye Movement Strategies Improve Clinical Outcomes and EEG Activity in Stroke Patients, a Randomized Controlled Trial

Introduction: The majority of our patients with middle cerebral artery (MCA) infarcts have impaired latency of visual saccades, saccadic dysmetria and saccadic intrusions of pursuits. We wanted to see if the utilization of eye movement rehabilitation in cases of middle cerebral artery infarction would result in changes of brain function and patient clinical outcomes. Hypothesis: We assessed the hypothesis that visual training of fast and slow eye movements to novel targets will result in changes in EEG activity, decrease physical and cognitive impairment and increase clinical outcomes in stroke patients. Methods: A sample size of 60 subjects (80% power, alpha of 0.05 at 95% CI) with acute MCA ischemic stroke within the first 48 hours of clinical evolution were randomized to an active treatment (n=30) group that performed eye movement strategies and a matched control group (n= 30) that did not. All subjects underwent CT and MRI and received standard therapies and NIH Stroke Scales and QEEG. Results: A significant reduction of the NIHSS scale was found after a week of practicing our eye movement strategies, indicating a clinical improvement. There was a significant reduction of the DAR index after eye movement exercises. QEEG brain mapping demonstrated a significant reduction of the spectral power in the Delta and an increment in the Alpha bands also demonstrated with the reduction of the DAR index. The brain symmetry index significantly increased after eye movement exercises indicating an augmentation of balance of the absolute mean value of the hemispheric power difference in the frequency range from 1 to 30 Hz. There was a significant reduction of the PRI index after eye movement exercises, indicating an increment of the fast (alpha +beta), compared with the slow (delta + theta) activities. A significant correlation was found between NIHSS (before) and DAR (after). Conclusions: The stroke patients undergoing eyes exercises had a significant neurological recovery with decreased impairment and improvement of electrical brain activity both reflected in the modifications of the NIHSS scale, and the DAR and BSI QEEG indices and strong correlations of DAR post-exercise with NIHSS scores before eye movement training strategies.

Sugihara causality analysis of scalp EEG for detection of early Alzheimer's disease.

Recently, Sugihara proposed an innovative causality concept, which, in contrast to statistical predictability in Granger sense, characterizes underlying deterministic causation of the system. This work exploits Sugihara causality analysis to develop novel EEG biomarkers for discriminating normal aging from mild cognitive impairment (MCI) and early Alzheimer's disease (AD). The hypothesis of this work is that scalp EEG based causality measurements have different distributions for different cognitive groups and hence the causality measurements can be used to distinguish between NC, MCI, and AD participants. The current results are based on 30-channel resting EEG records from 48 age-matched participants (mean age 75.7 years) — 15 normal controls (NCs), 16 MCI, and 17 early-stage AD. First, a reconstruction model is developed for each EEG channel, which predicts the signal in the current channel using data of the other 29 channels. The reconstruction model of the target channel is trained using NC, MCI, or AD records to generate an NC-, MCI-, or AD-specific model, respectively. To avoid over fitting, the training is based on the leave-one-out principle. Sugihara causality between the channels is described by a quality score based on comparison between the reconstructed signal and the original signal. The quality scores are studied for their potential as biomarkers to distinguish between the different cognitive groups. First, the dimension of the quality scores is reduced to two principal components. Then, a three-way classification based on the principal components is conducted. Accuracies of 95.8%, 95.8%, and 97.9% are achieved for resting eyes open, counting eyes closed, and resting eyes closed protocols, respectively. This work presents a novel application of Sugihara causality analysis to capture characteristic changes in EEG activity due to cognitive deficits. The developed method has excellent potential as individualized biomarkers in the detection of pathophysiological changes in early-stage AD.

Alpha-theta effects associated with ageing during the Stroop test.

The Stroop effect is considered as a standard attentional measure to study conflict resolution in humans. The response of the brain to conflict is supposed to change over time and it is impaired in certain pathological conditions. Neuropsychological Stroop test measures have been complemented with electroencephalography (EEG) techniques to evaluate the mechanisms in the brain that underlie conflict resolution from the age of 20 to 70. To study the changes in EEG activity during life, we recruited a large sample of healthy subjects of different ages that included 90 healthy individuals, divided by age into decade intervals, which performed the Stroop test while recording a 14 channel EEG. The results highlighted an interaction between age and stimulus that was focused on the prefrontal (Alpha and Theta band) and Occipital (Alpha band) areas. We concluded that behavioural Stroop interference is directly influenced by opposing Alpha and Theta activity and evolves across the decades of life.

Readying the head and steadying the heart: a review of cortical and cardiac studies of preparation for action in sport

Expert sport stars reliably execute their skills with remarkable precision and accuracy. To provide an insight into the mechanisms that underpin the superior performance of experts compared to novices, this article critically reviews experiments that have examined cortical activity (i.e., movement related cortical potentials; EEG spectral power) and cardiac activity (i.e., dynamic changes in heart rate) during preparation for action in self-paced aiming sports. It suggests that decelerations in heart rate and task-specific changes in EEG activity during preparation for action can explain superior expert performance. These psychophysiological responses are interpreted in terms of preparatory information processing and response programming, before suggestions for future research into the psychophysiology of preparation for action are outlined.

How we fall asleep: regional and temporal differences in electroencephalographic synchronization at sleep onset

ObjectivesWe hypothesized that the brain shows specific and predictable patterns of spatial and temporal differences during sleep onset (SO) reflecting a temporal uncoupling of electrical activity between different cortical regions and a dissociated wakelike and sleeplike electrocortical activity in different cortical areas. MethodsWe analyzed full-scalp electroencephalographic (EEG) recordings of 40 healthy subjects to investigate spatial and temporal changes of EEG activity across the wake-sleep transition. We quantified EEG sleep recordings by a fast Fourier transform (FFT) algorithm and by a better oscillation (BOSC) detection method to the EEG signals, which measured oscillatory activity within a signal containing a nonrhythmic portion. ResultsThe most representative spatial change at SO is the frontalization of slow-wave activity (SWA), while the θ activity, which mostly shares a similar temporal and spatial pattern with SWA, exhibits a temporo-occipital diffusion. The time course of these oscillations confirms that the changes of the dominant waves coexist with topographic changes. The waking occipital prevalence of α oscillations is progressively replaced by an occipital prevalence of θ oscillations. On the other hand, more anterior areas show a wide synchronization pattern mainly expressed by slow waves just below 4Hz and by spindle oscillations. ConclusionsThe whole pattern of results confirms that the centrofrontal areas showed an earlier synchronization (i.e., they fall asleep first). This finding implies a coexistence of wakelike and sleeplike electrical activity during sleep in different cortical areas. It also implies that the process of progressive brain disconnection from the external world as we fall asleep does not necessarily affect primary and higher-order cortices at the same time.

Altered resting state effective connectivity in long-standing vegetative state patients: An EEG study

ObjectiveRecent evidence mainly based on hemodynamic measures suggests that the impairment of functional connections between different brain areas may help to clarify the neuronal dysfunction occurring in patients with disorders of consciousness (DOC).The aim of this study was to evaluate effective EEG connectivity in a cohort of 18 patients in a chronic vegetative state (VS) observed years after the occurrence of hypoxic (eight) and traumatic or hemorrhagic brain insult. Methodswe analysed the EEG signals recorded under resting conditions using a frequency domain linear index of connectivity (partial directed coherence: PDC) estimated from a multivariate autoregressive model. The results were compared with those obtained in ten healthy controls. ResultsOur findings indicated significant connectivity changes in EEG activities in delta and alpha bands. The VS patients showed a significant and widespread decrease in delta band connectivity, whereas the alpha activity was hyper-connected in the central and posterior cortical regions. ConclusionThese changes suggest the occurrence of severe circuitry derangements probably due to the loose control of the subcortical connections. The alpha hyper-synchronisation may be due to simplified networks mainly involving the short-range connections between intrinsically oscillatory cortical neurons that generate aberrant EEG alpha sources. This increased connectivity may be interpreted as a reduction in information capacity, implying an increasing prevalence of stereotypic activity patterns. SignificanceOur observations suggest a remarkable rearrangement of connectivity in patients with long-standing VS. We hypothesize that in persistent VS, after a first period characterized by a breakdown of cortical connectivity, neurodegenerative processes, largely independent from the type of initial insult, lead to cortex de-afferentation and to a severe reduction of possible cortical activity patterns and states.

Validation of a neurofeedback paradigm: Manipulating frontal EEG alpha-activity and its impact on mood

It is claimed that neurofeedback (NF) is an effective treatment for a variety of psychiatric disorders. NF, within an operant conditioning framework, helps individuals to regulate cortical electroencephalographic (EEG) activity while receiving feedback from a visual or acoustic signal. For example, changing asymmetry between left and right frontal brain alpha activity by NF, is claimed to be an efficacious treatment for major depressive disorder. However, the specificity of this intervention in occasioning electrophysiological changes at target locations and target wave-frequencies, and its relation to changes in mood, has not been established. During a single session of NF, it was tested if the balance between left and right frontal alpha-activity could be changed, regardless of direction, in 40 healthy females. Furthermore, we investigated whether this intervention was electrophysiologically specific and if it was associated with changes in mood. Participants were able to decrease or increase frontal alpha-asymmetry during the intervention. However, no changes in mood were observed. Changes in EEG activity were specific in terms of location and wave-frequency.

State dependent changes in resting electroencephalographic activity in children with and without Attention Deficit Hyperactivity Disorder

State dependent changes in resting electroencephalographic activity in children with and without Attention Deficit Hyperactivity Disorder

EEG Based Detection of Alcoholics

The short term and long term effects of alcohol on various organs of the body, especially on the human brain is well established by numerous studies. Invasive methods such as Transcranial Magnetic Stimulation (TMS) and non invasive imaging techniques such as Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET), and functional MRI activated electro-encephalogram (EEG) have been used to study the changes in EEG activity due to alcoholism. Even with the advent of neuro imaging techniques, EEG happens to be an important tool for brain study providing a non- invasive and cost effective method to detect the effects of alcohol on the human brain. This paper discusses the harmful effects of alcohol on different organs of the body. The advances in the development of EEG signal processing algorithms over the past decade for alcoholic detection are reviewed and their limitations are reported. Further the use of EEG for mass screening of alcoholics and biometric application is discussed in detail.

The Effects of Neurofeedback Training on Memory Performance in Elderly Subjects

Neurofeedback or electroencephalographic operant conditioning (EEG-OC) is an EEG biofeedback technique used to train individuals to control or modify their cortical activity through learned self-regulation. Initially used for treating a variety of pathologies, neurofeedback has been employed more recently to improve the physical or cognitive performance of human beings. The purpose of this study is to assess the hypothesis of the effect of neurofeedback (the ‘awakened mind’ model) on the memory performance of subjects aged over 65. 30 participants were shared equally between 3 groups: an experimental group that underwent 4 neurofeedback training sessions; a non-neurofeedback group trained at relaxation; and a ‘waiting list’ control group. Results showed that the members of the Neurofeedback group learned to increase the spectral power of the alpha frequency range as well as the alpha/theta ratio, and that compared with the members of the two other groups, neurofeedback training resulted in a more pronounced decrease, albeit without any relation to changes in EEG activity and the level of stress and anxiety of participants undergoing such training. Yet contrary to expectations, no improvement of memory performance (differed recall of words and learning of lists of words) was observed. These mixed results, which suggest a wide range of applications, underline the need for a more systematic assessment of the potential applications of NFB training in elderly humans in order to be better able to specify the effects of the retained protocol on cognitive performance.

P24-4 Change in EEG activity associated with positive mood change after cutaneous stimulation over Shenmen

P24-4 Change in EEG activity associated with positive mood change after cutaneous stimulation over Shenmen

Micro-current electrical stimulation at bilateral wrist hand area facilitates changes in EEG activities associated with reduction in arousal: A randomized controlled trial

Micro-current electrical stimulation at bilateral wrist hand area facilitates changes in EEG activities associated with reduction in arousal: A randomized controlled trial

Changes in EEG activity before and after exhaustive exercise in sedentary women in neutral and hot environments

This study examined the effect of hyperthermia on brain electrical activity measured with encephalography during prolonged exhaustive exercise in a group of sedentary women (VO 2max = 35 ± 4 mL kg min −1). Two strenuous cycling exercises were performed either in neutral (N-Ex) or in heat (H-Ex) conditions. Tympanic temperature (Tty), heart rate (HR), body mass loss (BML), plasma volume decrease, and brain electrical activity [EEG: α (8–13 Hz) and β(13–30 Hz)-band and α/ β index of fatigue: the ratio between EEG activity in the α band and β-band] were recorded throughout the cycling sessions. The Tty increase 1.0 °C in the N-Ex and 1.8 °C in H-Ex. HR increased in both sessions but with significantly higher values during the H-Ex session when compared with the N-Ex session ( p < 0.001) (from 85 ± 4 beats min −1 to 164 ± 6 beats min −1 and from 83 ± 6 beats min −1 to 181 ± 8 beats min −1, respectively in N-Ex and in H-Ex). This was associated with a significantly higher BML ( p < 0.05) and a higher plasma volume decrease in the H-Ex session ( p < 0.01). The α/ β index increased significantly during both trials particularly during the H-Ex session ( p < 0.05). This was associated with a significant decrease of time to exhaustion (−34%). We suggest that exhausting work in the heat induced a change in gross brain activity (alpha/beta ratio) compared to a longer, less thermally demanding exposure. Fatigue in the heat could be attributed to central factors as well as thermal, cardiac and hydro-electrolytic impairment.

EEG activity during the verbal-cognitive stage of motor skill acquisition

This study examined changes in EEG activity associated with motor performance during the verbal-cognitive stage of skill learning. Participants (n=14) were required to practice a sequential finger tapping task. EEG activity was recorded both before and after short-term practice, during finger tapping and during two control conditions. EEG power (Fz, Cz, Pz, T3, T4) and coherence (T3-Fz, T4-Fz, Fz-Cz, Fz-Pz) were computed for the theta (4-8 Hz), slow alpha (8-10 Hz), fast alpha (10-12 Hz), slow beta (12-20 Hz), and fast beta (20-28 Hz) bandwidths. Changes in motor performance were rapid during the very early stages of practice and then slowed in accord with the law of practice. These changes were accompanied by increases of theta power at Fz and beta coherence at T4-Fz, suggesting that progression through the verbal-cognitive stage of a sequential finger tapping task is accompanied by more narrowed attention and improved mapping between the stimuli and the finger movements.

Sensitization, epileptic-like symptoms and local synchronization in patients with paranoid schizophrenia

Recent findings indicate that changes in synchronization of neural activities underlying sensitization and kindling could be more comprehensively understood using nonlinear methods. With this aim we have examined local synchronization using novel measure of coarse-grained information rate (CIR) in 8 EEG signals recorded at different cortical areas in 44 patients with paranoid schizophrenia. The values of local synchronization that could reflect sensitization related changes in EEG activities of cortical sites were then related to psychometric measures of epileptic-like symptoms and positive and negative schizophrenia symptoms (PANSS). While no significant correlations between CIR and positive and negative symptoms have been found, statistically significant relationships described by Spearman correlation coefficients between CIR indices and results of LSCL-33 have been observed in 7 (of 8) EEG channels (r in the range from 0.307 to 0.374, p<0.05). Results of this study provide first supportive evidence for the relationship between local synchronization measured by CIR and epileptic-like symptoms in schizophrenia.