Extraction of abnormal EEG with slow waves and its display method

A study carried out by light and electron microscopy of the behaviour of different tendons when subjected to lateral stretching and longitudinal splitting. Tendons like the FDS are more resistant to lateral stretching and show greater shredding. The structure of the tendon shows criss-crossing of the fibrils, necessary to stand up to the greater stress to which the tendon is normally exposed.     

Behaviour-related effects of nicotine on slow EEG waves in basal nucleus-lesioned rats

The basal magnocellular nucleus is assumed to play a crucial role in cholinergic activation of the cortical EEG. The aim of this study was to establish whether intraperitoneally applied nicotine may counteract the power asymmetry of the slow waves in the cortical EEG of both hemispheres after an unilateral lesion in the basal nucleus. In 17 rats the basal nucleus (substantia innominata/ventral pallidum) was unilaterally lesioned by ibotenic acid. The lesion produced unilateral power increases of all frequencies up to 20 Hz in the frontal EEG that increased with higher arousal level. Additionally, synchronized spike and wave discharges appeared in the frontal EEG. The results indicate that the basal nucleus suppresses especially the delta EEG waves in the frontal motor cortex during motor active behaviour. Nicotine (0.1 and 1 mg/kg) partially counteracts the power asymmetry of frontal slow waves (2-6 Hz) only during exploratory sniffing but not during grooming and waking immobility. Physostigmine (1 mg/kg) was also effective during exploratory sniffing. The results may indicate a role of nicotinic mechanisms in the information input component of exploratory behaviour.     

Relationship between sleep spindles and hypersomnia

Despite the substantial experimental literature that has accrued on factors associated with a reduction in neglect, few empirical studies have attempted to extrapolate these findings to clinical assessment and evaluate the efficacy of neglect-reducing strategies on patient performance. The current study developed a modified version of the Raven's Coloured Progressive Matrices (RCPM) by aligning the response alternatives in a column, in the right hemispace. Three groups of patients (right brain-damaged (RBD) with neglect, RBD without neglect, and orthopaedic controls) were administered abbreviated versions of the revised format, and performance was compared to the standard presentation format. The efficacy of left cues with the revised format was also investigated. Presence of neglect was assessed via the Schenkenberg Line Bisection Task and the Bells Test. Results showed a significant performance decrement among RBD neglect patients under all conditions. However, contrary to predictions, RBD neglect patients did not reveal significantly better performance on the revised version as compared to the standard presentation format. No significant effects associated with left side cueing were observed. The finding that no significant performance changes emerged as a function of stimulus modification and verbal prompts suggests that, although these manipulations may be employed by clinicians to maximize patient performance, empirical support for the efficacy of these procedures is lacking.     

Coordinated interactions between hippocampal ripples and cortical spindles during slow-wave sleep

Sleep is characterized by a structured combination of neuronal oscillations. In the hippocampus, slow-wave sleep (SWS) is marked by high-frequency network oscillations (approximately 200 Hz "ripples"), whereas neocortical SWS activity is organized into low-frequency delta (1-4 Hz) and spindle (7-14 Hz) oscillations. While these types of hippocampal and cortical oscillations have been studied extensively in isolation, the relationships between them remain unknown. Here, we demonstrate the existence of temporal correlations between hippocampal ripples and cortical spindles that are also reflected in the correlated activity of single neurons within these brain structures. Spindle-ripple episodes may thus constitute an important mechanism of cortico-hippocampal communication during sleep. This coactivation of hippocampal and neocortical pathways may be important for the process of memory consolidation, during which memories are gradually translated from short-term hippocampal to longer-term neocortical stores.     

Homeostatic process and sleep spindles in patients with sleep-maintenance insomnia: effect of partial (21 h) sleep deprivation

Port Pirie is 230 km north of Adelaide, the capital of South Australia. The major industry in the city is a lead smelter owned by Pasminco. Fume, dust, and fugitive emissions from the smelter have been deposited in and around Port Pirie over the past 100 years. The results presented in this paper are from an air monitoring station situated at the southeast entrance of the smelter, approximately 600 m from the blast furnace. Measurements include total suspended particulate (TSP) and total suspended particulate lead (TSPL) reported as concentrations (microgram/m3). Data are available from 1986 to 1996 and consist of 548 measurements. Analysis of geometric mean concentration levels by wind direction showed that while for TSP there was little relationship with wind direction, TSPL increased substantially as the wind came from the direction of the smelter. An analysis of geometric mean concentration levels by wind speed showed that TSP was significantly correlated with wind speed for all wind sectors apart from winds coming from the smelter production area. The lack of correlation between TSP and wind speed when the wind blows from the direction of the smelter is probably due to the dilution effect of particulate from a point source as wind speed increases. TSPL was significantly correlated with wind speed for all wind sectors apart from winds coming from the city. As expected, both TSP and TSPL concentrations were significantly lower on days when rain fell. Both mean geometric TSP and TSPL concentrations were lower in the period 1993-1996 than in 1986-1992. Multiple linear regression analysis was used to demonstrate that this decline was statistically significant after adjusting for weather conditions. Wind directions were divided into four sectors: winds from the smelter production area; winds from the smelter nonproduction area; winds from the zinc wharf and east of the city; and winds from the city. Structural equation models for each sector were used to demonstrate that the decline in geometric mean TSPL concentrations over the two periods were of a similar order of magnitude for all four sectors. The relevance of this to the lead abatement programs that have been undertaken both within the city of Port Pirie and inside the smelter itself is discussed.     

Evening administration of melatonin and bright light: interactions on the EEG during sleep and wakefulness

PROBLEM: Human leukocyte antigen (HLA)-G is uniquely expressed on extravillous cytotrophoblasts of the placenta and is postulated to be a mediator of maternal immune tolerance. Although it was originally considered to be nonpolymorphic, variations of the HLA-G DNA sequence have been reported, and a limited number of HLA-G alleles been defined. METHOD OF STUDY: The HLA-G wild-type sequence was compared with HLA-A2 with regard to the conservation of functionally essential parts of classical HLA-I molecules. HLA-G polymorphisms were analyzed under the aspect of ethnic differences, site, and consequences for postulated molecule functions. RESULTS: HLA-G exhibits a high degree of conservation relative to HLA-A2 in functionally relevant sites of HLA-class I molecules. However, polymorphic sites in HLA-G and classical HLA loci are not congruent. CONCLUSION: The type and localization of HLA-G polymorphisms suggest that different parts of HLA-G molecule underlie different selective constraints.     

Spindle frequency activity in the sleep EEG: individual differences and topographic distribution

Focal magnetic transcranial stimulation (TCS) is employed for mapping of the motor cortical output to abductor digiti minimi (ADM) muscle. The aim of this study was to evaluate the interhemispheric asymmetries in normals. Motor maps were obtained through motor evoked potentials (MEPs) recordings from ADM muscle in 20 healthy subjects in right and left hemispheres TCS. Measurement of several indexes such as excitability threshold, MEPs amplitude, MEPs latency, and silent period duration did not show differences between the hemispheres. Moreover, no interhemispheric asymmetries were found when the amplitude ratio values were analyzed. The hand motor cortical area, as represented by the number of responsive sites (3.6 vs. 3.5) and the "hot spot" site localization presented a fairly symmetrical organization. Absolute values displayed a relatively wide intersubject variability, while their interhemispheric differences were extremely restricted. This observation can offer a new tool in diagnosing and following up neurological disorders affecting the central motor system, mainly for those concerning monohemispheric lesions.     

Effects of sleeping in a chemical protective mask on sleep quality and cognitive performance

PURPOSE: We wanted to determine whether sleep is disrupted when soldiers sleep in a new chemical protective mask, the M40. Sleep quantity and quality, extent of protection provided by the mask during sleep, and next day performance were assessed. METHOD: After several days of training, 9 male soldiers slept with and without the M40 mask on four occasions. RESULTS: Soldiers were able to tolerate the mask for most or all of the night. However, sleep, as assessed by wrist-worn activity monitors, was significantly disturbed. Minutes (mean +/- SEM) of waking significantly increased, from 25 +/- 2.1 to 86 +/- 8.5 per night (p < 0.001), and number of awakenings rose from 8 +/- 0.6 to 20 +/- 0.9 (p < 0.0001). Soldiers reported that it took longer and was more difficult to fall asleep when wearing the mask. Errors on a choice reaction time task increased significantly and subjects reported greater fatigue and sleepiness the day after sleeping in the mask. Protection provided by the masks varied substantially among subjects and declined over the course of the study. Some soldiers were protected throughout the night but others were only protected intermittently. CONCLUSION: We conclude that sleeping in the chemical protective mask should only be done when necessary, given the adverse effects on sleep and daytime function, as well as the variability of protection, of the mask.     

Cortical potentials time-locked to EKG-R waves during wakefulness and slow wave sleep (stage 2) in the mankind (author's transl)

The purpose of this paper was to investigate whether cardiovascular afferent impulses could be recorded on a human scalp as computer-averaged cortical potentials time-locked to EKG-R waves. The results obtained were as follows. 1) Cortical potentials time-locked to EKG-R waves (EKG-EP) could be recorded on scalps of eleven healthy volunteers and within its pattern, triple negative large peaks could be seen during both wakefulness and slow wave sleep (stage 2). 2) Within triple negative large peaks, the 2nd negative peak were most stable and its averaged latencies were 224.1 +/- 32.4 msec. during wakefulness and 257.1 +/- 76.7 msec. during slow wave sleep (stage 2) and the 3rd negative peak had been found more frequently in the slow wave sleep than in the wakefulness. 3) EKG-EPs were analogous with those of auditory evoked potentials time-locked to EKG-R waves (EKG-AEP) if both were recorded in the same concious level. 4) Both latencies of the 2nd negative peak of the EKG-EPs and that of the largest negative peak of the EKG-AEPs were consistent each other with high ratio resulting r = 0.81 (P less than 0.01) in the wakefulness and r = 0.966 (P less than 0.001) in the slow wave sleep (stage 2) respectively.     

Data sampling under the interface of windows in the EEG signal processing system & analysis

Staphylococcus aureus meningitis is a rare but well recognized condition which had a high mortality and incidence of neurological sequelae. It is usually associated with chronic underlying conditions. A case is reported of S. aureus meningitis in a previously healthy young man. The epidemiology, microbiological findings and treatment of this condition are discussed.     

Assessment of digital EEG, quantitative EEG, and EEG brain mapping: report of the American Academy of Neurology and the American Clinical Neurophysiology Society

A. Digital EEG is an established substitute for recording, reviewing, and storing a paper EEG record. It is a clear technical advance over previous paper methods. It is highly recommended. (Class III evidence, Type C recommendation). B. EEG brain mapping and other advanced QEEG techniques should be used only by physicians highly skilled in clinical EEG, and only as an adjunct to and in conjunction with traditional EEG interpretation. These tests may be clinically useful only for patients who have been well selected on the basis of their clinical presentation. C. Certain quantitative EEG techniques are considered established as an addition to digital EEG in: C.1. Epilepsy: For screening for possible epileptic spikes or seizures in long-term EEG monitoring or ambulatory recording to facilitate subsequent expert visual EEG interpretation. (Class I and II evidence, Type A recommendation as a practice guideline). C.2. OR and ICU monitoring: For continuous EEG monitoring by frequency-trending to detect early, acute intracranial complications in the OR or ICU, and for screening for possible epileptic seizures in high-risk ICU patients. (Class II evidence, Type B recommendation as a practice option). D. Certain quantitative EEG techniques are considered possibly useful practice options as an addition to digital EEG in: D.1. Epilepsy: For topographic voltage and dipole analysis in presurgical evaluations. (Class II evidence, Type B recommendation). D.2. Cerebrovascular Disease: Based on Class II and III evidence, QEEG in expert hands may possibly be useful in evaluating certain patients with symptoms of cerebrovascular disease whose neuroimaging and routine EEG studies are not conclusive. (Type B recommendation). D.3. Dementia: Routine EEG has long been an established test used in evaluations of dementia and encephalopathy when the diagnosis remains unresolved after initial clinical evaluation. In occasional clinical evaluations, QEEG frequency analysis may be a useful adjunct to interpretation of the routine EEG when used in expert hands. (Class II and III evidence as a possibly useful test, Type B recommendation). E. On the basis of current clinical literature, opinions of most experts, and proposed rationales for their use, QEEG remains investigational for clinical use in postconcussion syndrome, mild or moderate head injury, learning disability, attention disorders, schizophrenia, depression, alcoholism, and drug abuse. (Class II and III evidence, Type D recommendation). F. On the basis of clinical and scientific evidence, opinions of most experts, and the technical and methodologic shortcomings, QEEG is not recommended for use in civil or criminal judicial proceedings. (Strong Class III evidence, Type E recommendation). G. Because of the very substantial risk of erroneous interpretations, it is unacceptable for any EEG brain mapping or other QEEG techniques to be used clinically by those who are not physicians highly skilled in clinical EEG interpretation. (Strong Class III evidence, Type E recommendation).     

Dynamical properties of the sleep EEG in different frequency bands

The information concerning the dynamic behavior of the sleep process gained by the usual evaluation of sleep EEGs according to the criteria of Rechtschaffen and Kales is limited. Therefore a new methodical approach is presented, which is a special case of spectral analyzed data processing. After digital band-pass filtering of the sleep EEG the root-mean-square (RMS) value of successive 20 s EEG epochs is calculated in defined frequency ranges. This procedure ensures to take into account the influence of the phase relation between different frequency components. The temporal course of these RMS values during the night reveals smooth curves with continuous transitions between different sleep states. In all frequency bands slow oscillations according to the sleep cycles are observable. Whereas the slow frequency bands have a temporal course with local maxima during non-REM and local minima during REM sleep, the fast frequency bands beta and gamma show the opposite behavior revealing higher RMS values during REM sleep. The relationship between the activities in different frequency bands is evaluated calculating the cross correlation coefficient. Taken together the procedure allows an objective and automated quantitative analysis of the sleep EEG. The main advantage of this approach is the characterization of the sleep cycle as a dynamic and continuous process. Compared to the classical analysis it provides a more detailed analysis of the sleep process, especially concerning the dynamics and microstructure of sleep.     

Fast color grouping and slow color inhibition: Evidence for distinct temporal windows for separate processes in preview search.

The authors report 4 experiments that examined color grouping and negative carryover effects in preview search via a probe detection task (J. J. Braithwaite, G. W. Humphreys, & J. Hodsoll, 2003). In Experiment 1, there was evidence of a negative color carryover from the preview to new items, using both search and probe detection measures. There was also a negative bias against probes on old items that carried the majority color in the preview. With a short preview duration (150 ms) carryover effects to new items were greatly reduced, but probe detection remained biased against the majority color in the old items. Experiments 2 and 4 showed that the color bias effects on old items could be reduced when these items had to be prioritized relative to being ignored. Experiment 3 tested and rejected the idea that variations in the probability of whether minority or majority colors were probed were crucial. These results show that the time course of color carryover effects can be separated from effects of early color grouping in the preview display: Color grouping is fast, and inhibitory color carryover effects are slow. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Joint time and time-frequency optimal detection of K-complexes in sleep EEG

Automated detection of waveforms such as delta and K-complex in the EEG is an important component of sleep stage monitoring. The K-complex is a key feature that contributes to sleep stages assessment. However, its automated detection is still difficult due to the stochastic nature of the EEG. In this paper, we propose a detection structure which can be interpreted as joint linear filtering operations in time and time-frequency domains. We also introduce a method of obtaining the optimum detector from training data, and we show that the resulting receiver offers better performances than the one obtained via the Fisher criterion maximization. The efficiency of this approach for K-complexes detector design is explored. It results from this study that the obtained receiver is potentially the best one which can be found in the literature. Finally, it is emphasized that this methodology can be advantageously used to solve many other detection problems.     

Topology of the principal EEG elements of sleep analyzed by analogue filters

In order to compare the venodilation effect of morphine in normal individuals (22) with that in patients (13) with heart failure morphine sulfate (0.1 mg/kg) was administered to 13 patients with mild pulmonary edema. After morphine congestive symptoms improved and venodilation was induced as determined by two independent techniques: venous pressure fell 10.2 mm Hg by the isolated hand technique and the venous volume of the forearm increased by 0.48 cc/100 ml, measured by equilibration technique. Neither finding differed from those in normal individuals. Reflex venoconstriction noted on the taking of a single deep breath was unaffected by morphine administration and was similar to that observed in normal subjects. Since the drug morphine sulfate does not cause a major pooling of blood in the limbs, the favorable effect of narcotics in patients with pulmonary edema must be caused by other mechanisms such as splanchnic pooling, afterload reduction or reduced breathing effort.     

Spectral power and coherence analysis of sleep EEG in AIDS patients: decrease in interhemispheric coherence

Fifteen patients aged between 26 and 55 years with the acquired immunodeficiency syndrome (AIDS) and various cerebral manifestations of the disease underwent an all-night sleep electroencephalogram (EEG) registration. The recordings of 15 age-matched volunteers were examined as controls. Sleep stages were determined visually and the following spectral analysis was based on corresponding artifact-free 40-second periods. The sampling rate was 64 second-1, the spectral resolution was 0.25 Hz and the frequency ranged from 0.25-24 Hz. The power density spectra of eight EEG derivations (left and right frontopolar, frontal, central and occipital; reference montage to the ipsilateral Cb electrodes) and the coherence spectra of interhemispheric (interfrontal, interoccipital) and intrahemispheric (frontooccipital, left and right) channel pairs were computed. The power density of the patients in the 11.5-13-Hz frequency range of nonrapid eye movement (NREM) sleep was considerably lower than that of the controls (p < 0.05 and p < 0.01 at left and right frontal derivations, two-tailed Mann-Whitney U test). The power density of rapid eye movement (REM) sleep showed no consistent differences between the two groups. The interfrontal coherence of the whole frequency range below 12 Hz was markedly lower in the patient group. This applied to NREM sleep and also to REM sleep (p < 0.01 and p < 0.001 for different frequency bands between 1 and 12 Hz in NREM and REM sleep). Possible relations to clinical features are discussed.     

Circadian and homeostatic influences on sleep in the squirrel monkey: sleep after sleep deprivation

A series of sleep deprivation (SD) experiments were performed to examine the relative influence of circadian and homeostatic factors on the timing of sleep in squirrel monkeys free-running in constant illumination. All SDs started at the beginning of subjective night and lasted 0, 1/4, 1/2, 1, 1 1/4, or 1 1/2 circadian cycles. These six lengths represented three pairs: (0.1), (1/4, 1 1/4), (1/2, 1 1/2). Within each pair, SD ended at the same circadian phase but differed by one circadian cycle in duration. Both before and after SD, consolidated sleep (CS) episodes occurred predominantly during subjective night, even after long SDs ending at the beginning of subjective day. CS duration was strongly influenced by circadian phase but had no overall correlation with prior wake duration. Sleep loss incurred during SDs longer than 1/4 cycle was only partially recovered over the next two circadian cycles, though total sleep duration was closer to baseline levels after the second circadian cycle after SD. There was a trend toward a positive correlation between prior wake duration and the amount of NREM and delta activity measures during subjective day. Delta activity was not increased in the first 2 hours of CS after the SD. Relatively high levels of delta activity occurred immediately after the SD ended and again at the time of baseline CS onset. These data indicate that the amount of sleep and delta activity after SD in squirrel monkeys is weakly dependent on prior wake duration. Circadian factors appear to dominate homeostatic processes in determining the timing, duration and content of sleep in these diurnal primates.     

Citalopram: differential sleep/wake and EEG power spectrum effects after single dose and chronic administration

The sleep/wake effects of the selective serotonin re-uptake inhibitor citalopram were studied in both a single-dose study with three dose levels (0.5, 2.0 and 5.0 mg/kg), and a 5-week chronic administration study (15 mg/kg/24 h). Single doses of citalopram resulted in a dose-dependent inhibition of rapid eye movement (REM) sleep. After chronic citalopram treatment there was a sustained REM sleep inhibition. Single doses of citalopram resulted in only minor changes in non-REM (NREM) sleep as well as in NREM EEG power spectral density. Chronic administration resulted in a major shift from SWS-2 to SWS-1. The observed corresponding changes in EEG power density were regional. A 30 to 40 percent reduction of power density in the 0.5-15 Hz range in the fronto-parietal EEG derivation was seen for the whole 8-h registration period. In the fronto-frontal EEG derivation only minor changes were seen. A decreasing trend in NREM sleep power density between 0.5 and 7 Hz, usually seen during the course of the light period, was not observed in the chronic condition, but was seen in control and single-dose condition, suggesting altered diurnal distribution of slow wave activity in the chronic condition. The data indicate that acute and chronic administration of citalopram shows clear differences in sleep effect, which may be caused by alteration of serotonergic transmission, and may be related to the antidepressant effect.