EEG Waves Research Articles

Implementation of a control system for a power wheelchair with induction of a β/α ratio by visual feedback.

Techniques using electroencephalography (EEG)-based brain computer interfaces (BCIs) have been developed and are eagerly anticipated as novel interfaces for controlling power wheelchairs. In addition to the BCIs, smart glass technology has been developed. In our previous study, we propose a prototype of an intuitive control system for a power wheelchair; this system comprises a simple EEG recorder, smart glass, and a microcomputer. Using this system, the power wheelchair moves straight ahead when a user concentrates, stops when the user blinks, and turns left or right when the user tilt his/her neck to the left or right, respectively. A β/α ratio as an indicator of the concentration and blinks are detected from raw EEG waves, and the tilting of the neck is detected by acceleration sensors in the smart glass. In this study, we proposed a new control system which display the visual feedback of the β/α ratio on the smart glass to induce user's concentration. Our results show that during the experiment, the system successfully worked and induced for the β/α ratio in specific concentrating states.

Frequency of EEG Changes In Different Types of Clinically Diagnosed Epileptic Patients

Background: Diagnosis of epilepsy is based mainly on clinical history and examination. EEG constitutes the single most valuable laboratory test in the evaluation of patients with epilepsy. Objective: The objective of the present study was to find out the frequency of EEG abnormality among different types of clinically diagnosed epileptic patients.
 Methods: This cross-sectional study was carried out in the Department of Neurology, Bangabandhu Sheikh Mujib Medical University, Dhaka. A total of 152 epileptic patients attended in the Epilepsy Clinic, General OPD and EEG room of the Department of Neurology were enrolled for this study. Information on socio-demographic and seizure characteristics was obtained. The records from patients were obtained using the standard data collection form.
 Result: Out of 152 epileptic patients male were 62.5% and female were 37.5%, mean age was 20.69 ± 11.83 years. Abnormal EEG was found in 81 (53.3%) patients. Most of the patients 64 (79.0%) had generalized epileptic discharge and 17 (21.0%) had focal epileptic discharge. Out of 81 patients with abnormal EEG wave, 31 (38.3%) patients had spike and wave, 26 (32.1%) patients had sharp wave and 24 (29.6%) patients had multiple types of EEG wave.
 Conclusion: The EEG is an important tool for diagnosing an epilepsy syndrome, knowledge of which aids in planning treatment and determining prognosis.
 Bangladesh Journal of Neuroscience 2016; Vol. 32 (2): 63-67

Correlations between personality traits and specific groups of alpha waves in the human EEG.

Background. Different individuals have alpha waves with different wavelengths. The distribution of the wavelengths is assumed to be bell-shaped and smooth. Although this view is generally accepted, it is still just an assumption and has never been critically tested. When exploring the relationship between alpha waves and personality traits, it makes a huge difference if the distribution of the alpha waves is smooth or if specific groups of alpha waves can be demonstrated. Previous studies have not considered the possibility that specific groups of alpha waves may exist.Methods. Computerized EEGs have become standard, but wavelength measurements are problematic when based on averaging procedures using the Fourier transformation because such procedures cause a large systematic error. If the actual wavelength is of interest, it is necessary to go back to basic physiology and use raw EEG signals. In the present study, measurements were made directly from sequences of alpha waves where every wave could be identified. Personality dimensions were measured using an inventory derived from the International Personality Item Pool.Results. Recordings from 200 healthy individuals revealed that there are three main groups of alpha waves. These groups had frequencies around 8, 10, and 12 waves per second. The middle group had a bimodal distribution, and a subdivision gave a total of four alpha groups. In the center of each group, the degree of extraversion was high and the degree of neuroticism was low. Many small differences in personality traits were found when the centers were compared with one another. This gave four personality profiles that resemble the four classical temperaments. When people in the surrounding zones were compared with those in the centers, relatively large differences in personality traits were found.Conclusions. Specific groups of alpha waves exist, and these groups have to be taken into account when correlations are made to personality dimensions and temperament types. There is a link between alpha waves and personality traits, and this link implies that there is an underlying relationship. To explain the nature of this relationship, there are two hypotheses that can be applied. One of these deals with the general organization of the forebrain and the other explains why the brain generates alpha waves.

A novel multivariate STeady-state index during general ANesthesia (STAN).

The assessment of the adequacy of general anesthesia for surgery, namely the nociception/anti-nociception balance, has received wide attention from the scientific community. Monitoring systems based on the frontal EEG/EMG, or autonomic state reactions (e.g. heart rate and blood pressure) have been developed aiming to objectively assess this balance. In this study a new multivariate indicator of patients' steady-state during anesthesia (STAN) is proposed, based on wavelet analysis of signals linked to noxious activation. A clinical protocol was designed to analyze precise noxious stimuli (laryngoscopy/intubation, tetanic, and incision), under three different analgesic doses; patients were randomized to receive either remifentanil 2.0, 3.0 or 4.0ng/ml. ECG, PPG, BP, BIS, EMG and [Formula: see text] were continuously recorded. ECG, PPG and BP were processed to extract beat-to-beat information, and [Formula: see text] curve used to estimate the respiration rate. A combined steady-state index based on wavelet analysis of these variables, was applied and compared between the three study groups and stimuli (Wilcoxon signed ranks, Kruskal-Wallis and Mann-Whitney tests). Following institutional approval and signing the informed consent thirty four patients were enrolled in this study (3 excluded due to signal loss during data collection). The BIS index of the EEG, frontal EMG, heart rate, BP, and PPG wave amplitude changed in response to different noxious stimuli. Laryngoscopy/intubation was the stimulus with the more pronounced response [Formula: see text]. These variables were used in the construction of the combined index STAN; STAN responded adequately to noxious stimuli, with a more pronounced response to laryngoscopy/intubation (18.5-43.1%, [Formula: see text]), and the attenuation provided by the analgesic, detecting steady-state periods in the different physiological signals analyzed (approximately 50% of the total study time). A new multivariate approach for the assessment of the patient steady-state during general anesthesia was developed. The proposed wavelet based multivariate index responds adequately to different noxious stimuli, and attenuation provided by the analgesic in a dose-dependent manner for each stimulus analyzed in this study.

Acupuncture at SP6 Point in Lower Extremities Improved Patients' Insomnia, Which Was Also Shown Through Ryodoraku Electrical Measurements.

Traditional Chinese medicine (TCM) applies acupuncture to treat insomnia and the SP6 is known to be beneficial for sleep. This study aimed to investigate the effects of acupuncture at SP6 on resting electroencephalogram (EEG), meridian electrical activity (Ryodoraku), and stress in patients with confirmed insomnia. In this single-blind, randomized clinical trial subjects (N=70) from TCM treated outpatients were randomized to receive TCM based acupuncture with manual stimulation (experimental) or sham stimulation (control) treatment. Acupuncture was applied to SP6 for 20 minutes on the spleen meridian of the foot in experimental subjects and controls received sham intervention. Significant changes between pre- and post-intervention were found in all electrical conductance values for the 12 meridians (Ryodoraku scores) in either control or experimental groups (fold change from 1.15 to 2.03) (P values <0.00 1). Eight meridians showed significantly different changes in Ryodoraku scores between pre- and post-intervention in the experimental group compared to the control group (fold change from 1.16 to 1.36) (P<0.05). EEG wave signals did not change with intervention in either group (P values ≥0.209). In summary, acupuncture at the SP6 acupoint altered meridian electrical activity of the lung periecardium, har, small intestine, sanjiao, spleen, bladder, and stomach meridians (P values <0.05) in patients with insomnia. Further studies are necessary to evaluate how changes in these meridians may affect insomnia.

Cerebral Regulation in Different Maximal Aerobic Exercise Modes

We investigated cerebral responses, simultaneously with peripheral and ratings of perceived exertion (RPE) responses, during different VO2MAX-matched aerobic exercise modes. Nine cyclists (VO2MAX of 57.5 ± 6.2 ml·kg−1·min−1) performed a maximal, controlled-pace incremental test (MIT) and a self-paced 4 km time trial (TT4km). Measures of cerebral (COX) and muscular (MOX) oxygenation were assessed throughout the exercises by changes in oxy- (O2Hb) and deoxy-hemoglobin (HHb) concentrations over the prefrontal cortex (PFC) and vastus lateralis (VL) muscle, respectively. Primary motor cortex (PMC) electroencephalography (EEG), VL, and rectus femoris EMG were also assessed throughout the trials, together with power output and cardiopulmonary responses. The RPE was obtained at regular intervals. Similar motor output (EMG and power output) occurred from 70% of the duration in MIT and TT4km, despite the greater motor output, muscle deoxygenation (↓ MOX) and cardiopulmonary responses in TT4km before that point. Regarding cerebral responses, there was a lower COX (↓ O2Hb concentrations in PFC) at 20, 30, 40, 50 and 60%, but greater at 100% of the TT4km duration when compared to MIT. The alpha wave EEG in PMC remained constant throughout the exercise modes, with greater values in TT4km. The RPE was maximal at the endpoint in both exercises, but it increased slower in TT4km than in MIT. Results showed that similar motor output and effort tolerance were attained at the closing stages of different VO2MAX-matched aerobic exercises, although the different disturbance until that point. Regardless of different COX responses during most of the exercises duration, activation in PMC was preserved throughout the exercises, suggesting that these responses may be part of a centrally-coordinated exercise regulation.

Spherical Harmonics Reveal Standing EEG Waves and Long-Range Neural Synchronization during Non-REM Sleep.

Previous work from our lab has demonstrated how the connectivity of brain circuits constrains the repertoire of activity patterns that those circuits can display. Specifically, we have shown that the principal components of spontaneous neural activity are uniquely determined by the underlying circuit connections, and that although the principal components do not uniquely resolve the circuit structure, they do reveal important features about it. Expanding upon this framework on a larger scale of neural dynamics, we have analyzed EEG data recorded with the standard 10–20 electrode system from 41 neurologically normal children and adolescents during stage 2, non-REM sleep. We show that the principal components of EEG spindles, or sigma waves (10–16 Hz), reveal non-propagating, standing waves in the form of spherical harmonics. We mathematically demonstrate that standing EEG waves exist when the spatial covariance and the Laplacian operator on the head's surface commute. This in turn implies that the covariance between two EEG channels decreases as the inverse of their relative distance; a relationship that we corroborate with empirical data. Using volume conduction theory, we then demonstrate that superficial current sources are more synchronized at larger distances, and determine the characteristic length of large-scale neural synchronization as 1.31 times the head radius, on average. Moreover, consistent with the hypothesis that EEG spindles are driven by thalamo-cortical rather than cortico-cortical loops, we also show that 8 additional patients with hypoplasia or complete agenesis of the corpus callosum, i.e., with deficient or no connectivity between cortical hemispheres, similarly exhibit standing EEG waves in the form of spherical harmonics. We conclude that spherical harmonics are a hallmark of spontaneous, large-scale synchronization of neural activity in the brain, which are associated with unconscious, light sleep. The analogy with spherical harmonics in quantum mechanics suggests that the variances (eigenvalues) of the principal components follow a Boltzmann distribution, or equivalently, that standing waves are in a sort of “thermodynamic” equilibrium during non-REM sleep. By extension, we speculate that consciousness emerges as the brain dynamics deviate from such equilibrium.

Fast (40–150 Hz) oscillations are associated with positive slow waves in the ictal EEGs of epileptic spasms in West syndrome

ObjectiveTo elucidate the generative mechanisms of epileptic spasms (ESs) in West syndrome, we investigated the temporal relationship between scalp fast (40–150Hz) oscillations (FOs) and slow waves in the ictal electroencephalograms (EEGs) of ESs. MethodsIn 11 infants with WS, ictal FOs were detected in a bipolar montage based on spectral and waveform criteria. Their temporal distribution was analyzed in terms of the positive peaks (trough point, TT) of identical EEG data in a referential montage. Among six EEG data sections defined according to TT, the number of FOs, peak power values, and peak frequencies were compared. ResultsWe identified a total of 1014 FOs (946 gamma and 68 ripple oscillations), which clustered closely at TT. The number of gamma oscillations in the 1s epoch including TT was significantly higher than those in the prior and subsequent phases. Peak power values and frequencies tended to be higher in these positive phase sections. ConclusionsThe temporal association of FO clustering and positive slow waves in the ictal EEGs of ES indicated that active neuronal firing related to FOs underlies the generation of ESs and their ictal slow waves.

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

A novel approach to pre-slaughter stunning of chickens has been developed in which birds are rendered unconscious by progressive hypobaric hypoxia. Termed Low Atmospheric Pressure Stunning (LAPS), this approach involves application of gradual decompression lasting 280s according to a prescribed curve. We examined responses to LAPS by recording behaviour, electroencephalogram (EEG) and electrocardiogram (ECG) in individual male chickens, and interpreted these with regard to the welfare impact of the process. We also examined the effect of two temperature adjusted pressure curves on these responses. Broiler chickens were exposed to LAPS in 30 triplets (16 and 14 triplets assigned to each pressure curve). In each triplet, one bird was instrumented for recording of EEG and ECG while the behaviour of all three birds was observed. Birds showed a consistent sequence of behaviours during LAPS (ataxia, loss of posture, clonic convulsions and motionless) which were observed in all birds. Leg paddling, tonic convulsions, slow wing flapping, mandibulation, head shaking, open bill breathing, deep inhalation, jumping and vocalisation were observed in a proportion of birds. Spectral analysis of EEG responses at 2s intervals throughout LAPS revealed progressive decreases in median frequency at the same time as corresponding progressive increases in total power, followed later by decreases in total power as all birds exhibited isoelectric EEG and died. There was a very pronounced increase in total power at 50–60s into the LAPS cycle, which corresponded to dominance of the signal by high amplitude slow waves, indicating loss of consciousness. Slow wave EEG was seen early in the LAPS process, before behavioural evidence of loss of consciousness such as ataxia and loss of posture, almost certainly due to the fact that it was completely dark in the LAPS chamber. ECG recordings showed a pronounced bradycardia (starting on average 49.6s into LAPS), often associated with arrhythmia, until around 60s into LAPS when heart rate levelled off. There was a good correlation between behavioural, EEG and cardiac measures in relation to loss of consciousness which collectively provide a loss of consciousness estimate of around 60s. There were some effects of temperature adjusted pressure curves on behavioural latencies and ECG responses, but in general responses were consistent and very similar to those reported in previous research on controlled atmosphere stunning with inert gases. The results suggest that the process is humane (slaughter without avoidable fear, anxiety, pain, suffering and distress). In particular, the maintenance of slow wave EEG patterns in the early part of LAPS (while birds are still conscious) is strongly suggestive that LAPS is non-aversive, since we would expect this to be interrupted by pain or discomfort.

Delta Activity at Sleep Onset and Cognitive Performance in Community-Dwelling Older Adults.

Frontal intermittent rhythmic delta activity (FIRDA) has long been considered to be an abnormal variant in the electroencephalogram (EEG) among older adults. Prior work also indicates a predominance of slow wave EEG activity among patients with dementia. However, instability of state control occurring with aging generally and among many neurodegenerative diseases raises the possibility that FIRDA might represent the intrusion of sleep related elements of the EEG into the waking state. We examined delta activity at sleep onset (DASO) in community-dwelling, older adults without dementia, and examined whether this activity is related to poorer cognitive performance. 153 community-dwelling, older adults without dementia underwent overnight polysomnography and measures of global cognition, delayed verbal memory, information processing speed, attention, inhibition, verbal naming, and visuospatial ability. Delta activity during sleep/wake transitions (scored either as Waking or N1) was analyzed visually. Participants were 83 women and 70 men, mean age 71.3 ± 0.6 y. DASO was present in 30 participants (19.6%). Age, years of education, sex, and body mass index did not differ between DASO (+) and (-) groups. Multiple regression analyses indicated faster reading of the Stroop color words in DASO (+) subjects (P = 0.007). None of the other cognitive domains differed between the two groups. DASO was relatively common in our sample of community-dwelling, older adults without dementia. DASO was not associated with poorer performance on any cognitive domain. Instead, individuals with DASO demonstrated better performance on a simple reading task. Although these findings suggest that an abnormal EEG activity may represent normal variation, our work underscores the importance of distinguishing DASO from FIRDA when examining sleep in older adults. A commentary on this article appears in this issue on page 725.

7. Identifying the pathological substrate(s) of complex partial seizures: Blumenfeld’s network inhibition hypothesis

Complex partial seizures – which often arise in the temporal lobes – are the most common seizures in adults and are often drug resistant. They involve transient episodes of impaired consciousness with behavioural arrest. Identifying the neural substrate for these common and drug-resistant attacks will be valuable not only for understanding epileptogenic networks, but also for evolving new pharmacologic or stimulation paradigms designed for complex partial seizures. Dr. Hal Blumenfeld at Yale University has offered a testable hypothesis concerning the neural substrate of complex partial seizures. Blumenfeld postulates (2012) : (1) that focal discharge arises somewhere in the brain, typically in the temporal lobes; (2) that the focal discharge spreads to subcortical structures that have strong inhibitory outputs, such as the septal nuclei; and (3) that the discharge in these structures suppresses activity in the arousal systems of the upper brain stem and diencephalon. Suppression of the arousal systems leads to unconsciousness, which is signaled by the onset of behavioural arrest and slow waves in the neocortical EEG. Blumenfeld’s hypothesis has not yet been tested in the amygdala-kindling model – the most widely used and drug-validated animal model of complex partial seizures. Tests involving the Blumenfeld hypothesis and amygdala-kindled rats are now underway in our laboratory. We predict that behavioural arrest in kindled animals will correlate with the onset of slow waves in the rat neocortex. We also predict that the behavioural arrest will not be suppressed by anti-epileptic drugs (AEDs), since AEDs do not suppress complex partial seizures in patients or the kindled amygdala focus in rats ( Albright and Burnham, 1980 ).

Electroencephalographic features of anti-N-methyl-D-aspartate receptor encephalitis in children

To investigate electroencephalographic (EEG) characteristics of anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis in children. Clinical data of 28 children diagnosed as anti-NMDAR encephalitis were retrospectively analyzed for EEG characteristics in different periods and severity of disease and outcome. Among the 28 patients with anti-NMDAR encephalitis, 15 were males and 13 were females. Their age at disease onset ranged from 1 year 3 months to 12 years 4 months. Patients were divided into mild group (5 cases) and severe group (23 cases). In the different stage of the disease, occipital background activity of the EEG was preserved in more than half of patients. Accompanied by the evolution of disease course, the occipital background activity and slow waves gradually recovered to normal. In the peak phase of disease, occipital background activity in the awake state was preserved in 4/5 patients of the mild group and 9/17 patients of the severe group. Alpha and theta band rhythms in non-rapid eye movement (NREM) sleep existed in 77% (17/22) patients. EEG monitoring showed delta brushes in 2 cases, and the delta brushes were mixed with background fast waves in one case; 71% (20/28) patients had epileptiform discharges in EEG during the course, and among them, 6 patients had secondary epilepsy. The background activity in the awake state and abnormal diffuse slow waves of EEG were evolved and gradually recovered during the course of the disease. Regardless milder or severe illness condition, occipital background activity was still preserved during different stages in most patients. Alpha and theta rhythms in NREM sleep might represent a relatively overt EEG characteristic. The presence of delta brush in EEG was rare, and sometimes they were difficult to be distinguished from fast wave activities caused by drugs. The presence of epileptiform discharges in EEG suggested the possibility of secondary epilepsy.

ID 399 – Investigation of patients with hippocampal sclerosis associated with unusual epileptic foci

Rationale Hippocampal sclerosis (HS) is usually associated with anterior temporal spikes/sharp waves in EEG. We aimed to investigate the differences between HS patients with unusual epileptic foci in comparison to typical foci. Methods 126 patients followed up with HS were evaluated. All MRIs were investigated for the presence of two major criteria of HS diagnosis, namely T1 atrophy and T2 hyperintensity. All EEG and video-EEG investigations (a total of 496) were re-evaluated for unusual epileptic activities except T1/2, F7/8, T3/4 foci. Post-operative seizure outcomes were investigated according to the Engel classification. Results There were 20 patients (9 males; 7 with bilateral HS) with unusual foci with a follow-up duration of 107.8 ± 89.3 months. Their findings were compared to 106 patients with usual HS. Statistical analysis could not show any difference between these groups. All but 2 showed drug-resistant course; 5 had status epilepticus and 5 had mental retardation without reaching statistical significance. Ten were operated and 7 of them were grouped as Engel classification 1. Conclusion Our study showed that unusual epileptic foci could be seen in 15.9% of HS patients. Although they had drug resistant course, they might show good post-operative outcome, when preoperative diagnostics were appropriately planned.

P-217: Effect of heart rate variability biofeedback on brain electrical activity in stage I hypertensive patients

Background The assessment of the functional activity of the brain in hypertensive patients is a prerequisite for an adequate treatment, but it is often limited to blood pressure parameters monitoring and rarely used in practice. Nevertheless, the proper functioning of the central nervous system is precisely a reaction to any influence, including therapy and biofeedback intervention, and allows for quality evaluation of the selected treatment. We aimed to determine the efficiency of combining heart rate variability biofeedback (HRV-BF) with pharmacological therapy in order to keep the normal brain activity in stage I hypertensive patients. Methods For this study fifty men, ages 40 to 60, with stage 1 hypertension were selected by physicians. The participants were randomly put into two groups: receiving medication only (control group, n = 25) and receiving medication with HRV-BF (study group, n = 25). The study group participated in 20 sessions of HRV-BF. Electroencephalogram (EEG) was recorded for both groups: before treatment started and after HRV-BF intervention. Results The changes in EEG wave structure between control and study groups differed after 3 weeks. In the control group alpha activity significantly decreased (p Conclusions Diffuse reduction in alpha activity, increase in slow-wave activity and other signs of EEG desynchronisation did not appear in stage I hypertensive patients treated with combination of HRV-BF and medication.

Effects of aspartame on the evaluation of electrophysiological responses in Wistar albino rats

Aspartame is a non-nutritive sweetener that is used predominantly in various ‘diet’ and ‘low-calorie’ products, such as beverages, instant breakfasts, desserts, breath mints, sugar-free chewing gum, vitamins, and pharmaceuticals, consumed by millions of people who are attempting weight loss, young adults and diabetic persons. On a weight basis, the metabolism of aspartame generates approximately 50% phenylalanine, 40% aspartic acid and 10% methanol. The detailed mechanisms of the effects of aspartame on the electrophysiological response are still unclear; therefore, this study was designed to clarify whether longer-term aspartame consumption has any effect on the electrophysiological response in Wistar albino rats. The oral administration of aspartame in a safe dose of 40mg/kg bodyweight/day (as recommended by EFSA, 2012) was tested in Wistar albino rats for a longer period (90 days). Electrophysiological responses, including heart rate variability (HRV) and electroencephalogram (EEG) pattern, were assessed in a folate-deficient animal model along with control animals using BIOPAC and EEG equipment (model RMS EEG–24 brain new-plus: RMS – Recorder and Medicare systems). In this study, the folate-deficient animal model was used to mimic human methanol metabolism in rats. After 90 days of aspartame treatment, a significant alteration was observable in the time domain [Mean RR (ms) SDNN (ms) RMSSD (ms) PNN50 (%)] and the frequency domain [LF, HF, and LF/HF ratio] with significantly impaired frequency and amplitude of the fronto-parietal and occipital EEG waves at p≤0.05. The results of this study clearly indicate that the oral consumption of aspartame reduced HRV, with sympathetic dominance and loss of vagal tone, and altered sympathovagal activity along with impairment of learning and memory, showing an additional effect on health within this study duration. The aspartame metabolites methanol and formaldehyde may be the causative factors behind the change observed.

Traveling Waves in the Human EEG during Voluntary Hand Movements

The trajectories of EEG traveling waves linked with movements of the right hand in a defined direction were recorded. A rectangle of 28 electrodes was positioned above the sensorimotor cortex, with seven electrodes in each row. A two-dimensional center-out reaching task was used. Targets appeared at the edge of the screen at random time intervals of 0.5–2.5 sec, with equal probabilities of appearing at the left, right, top, or bottom. The task was to use a joystick to move the cursor to touch the target, moving the cursor in one direction from the center to the edge. EEG traces were analyzed from the appearance of the target until it was touched. Spontaneous EEG waves showed phase anticipation in a local area of the left sensorimotor cortex and the posterior central parietal cortex on downward cursor movement (pulling movement of hand on joystick) as compared with the resting state and movements in the other three directions. Time smoothing of phase shift data using a sliding mean revealed otherwise cryptic constant components in the EEG resembling summation of evoked potentials.

Electroencephalographic Monitoring of Brain Wave Activity During Laparoscopic Surgical Simulation to Measure Surgeon Concentration and Stress: Can the Student Become the Master?

To measure gamma and alpha brain wave activity as a measurement of concentration and stress levels during surgical simulator performance of laparoscopic tasks to determine if expert surgeons have different brain activity patterns compared with intermediate and novice surgeons. After obtaining Institutional Review Board approval, 1st and 2nd year medical students, urology residents (PGY2-PGY5), and attending urologists from one institution were recruited. Participants were stratified by level of experience and performed laparoscopic tasks on the EDGE laparoscopic simulator. Subjects were evaluated for concentration and stress levels using the electroencephalography (EEG) data extracted from the MUSE(™) headband. The MUSE software developer kit (SDK) allowed quantification of gamma and alpha waves during each task. An analysis of variance was used to compare concentration and stress levels between groups. A total of 19 participants were recruited for the study and stratified by surgical experience into novice, intermediate, and expert laparoscopy groups: 6 medical students, 9 urology residents, and 4 attending urologists, respectively. Concentration and stress were quantified by calculating the area under the curve of the gamma and alpha EEG wave tracings. Stress was significantly lower in the attending urologists compared with the residents and medical students during the laparoscopic suturing and trended toward significance in the peg transfer task (P = 0.0003, P = 0.069). Concentration was significantly higher in the expert group compared with the less experienced groups during both the peg and suture tasks (P = 0.036, P = 0.0039). EEG brain activity in more experienced surgeons reveals a significant increase in concentration levels with a decrease in stress during simulated laparoscopic tasks compared with novices. This information may correlate with increased proficiency as well as provide objective feedback of progress along the learning curve with the MUSE SDK.

Drop attacks, falls and atonic seizures in the Video-EEG monitoring unit

PurposeWe set out to determine clinical and EEG features of seizures presenting with falls, epileptic drop attacks and atonia in the video EEG monitoring unit. MethodsWe searched the video EEG monitoring reports over a 5-year-period for the terms “drop”, “fall” and “atonic”. ResultsSeizures presenting as epileptic drop attacks, falls or atonia were found in 23/1112 (2%) admissions. About half of the patients suffering from these seizure types had developmental delay and learning difficulties and in half of the patients a lesion was seen on MRI which was often frontal. The presumed epileptogenic zone was frontal in many cases (43%), unclear with regards to a region or multifocal in 48% and posterior temporal/occipital in 2 patients (9%). EEG patterns recorded were paroxysmal fast activity, spike and wave discharges and EEG attenuation. Seizure related falls were seen in 8 cases (34%) with injuries recorded during Video EEG monitoring in half of those. ConclusionClinical and EEG features outlined here can help the clinician to recognise patients at risk for these devastating seizure types.

General features of the formation of EEG wave structure in children and adolescents living in Northern European Russia

The article presents the results of the analysis of EEG wave structure formation in children and adolescents aged 7-18 years living under severe conditions of the North. The approaches developed in discrete mathematics (the graph theory, the theory of network flows) were used to assess the time-frequency transformations of EEG patterns. We evaluated conditional probabilities of reciprocal transitions between the components of six frequency bands of E EG (delta, theta, alpha-1, alpha-2, beta-1, beta-2). We described age- and sex-related features as well as regional specificities of the EEG wave structure. We defined the age periods of reorganization of diffuse EEG activities into the main EEG rhythms; the role of distinct rhythms in the maintenance of the EEG wave structure and its dynamic rearrangements was also discussed. The age-related changes of the structure of EEG patterns form some general picture of the morphofunctional development of brain in children and adolescents at different stages of postnatal ontogenesis under severe climate and socio-economic conditions of the North.

Analyzing event related potentials using adaptive filter

ERPs (Event Related Potentials) are EEG signals which are directly measured from cortical electrical response to external stimuli such as feelings, sensual or cognitive events. The evaluation of the amplitude and latency of the ERP wave has important significance in evaluating neurological reflex. However, the ERP wave amplitude is small compared with the EEG wave, and considerably affected by the noise such as eyes, muscles, heart motion etc. In this paper, datasets are collected from ERPLAB and journals provided available datasets with the stimulus of sound and light. Using adaptive noise cancellation (ANC) combined with LMS algorithm the waves P300 of ERP were detected and separated. The algorithm was evaluated by the ratio SNR and average value. Results were compared with other published tools such as P300 calculation algorithm of ERPLAB softwar.