Significant EEG Differences Research Articles

Differential effects of sevoflurane and desflurane on frontal intraoperative electroencephalogram dynamics associated with postoperative delirium

Study objectiveIntraoperative electroencephalogram (EEG) patterns associated with postoperative delirium (POD) development have been studied, but the differences in EEG recordings between sevoflurane- and desflurane-induced anesthesia have not been clarified. We aimed to distinguish the EEG characteristics of sevoflurane and desflurane in relation to POD development. Design and patientsWe collected frontal four-channel EEG data during the maintenance of anesthesia from 148 elderly patients who received sevoflurane (n = 77) or desflurane (n = 71); 30 patients were diagnosed with delirium postoperatively. The patients were divided into four subgroups based on anesthetics and delirium status: sevoflurane delirium (n = 17), sevoflurane non-delirium (n = 60), desflurane delirium (n = 13), and desflurane non-delirium (n = 58). We compared spectral power, coherence, and pairwise phase consistency (PPC) between sevoflurane and desflurane, and between non-delirium and delirium groups for each anesthetic. Main resultsIn patients without POD, the sevoflurane non-delirium group exhibited higher EEG spectral power across 8.5–35 Hz (99.5% CI bootstrap analysis) and higher PPC from alpha to gamma bands (p < 0.005) compared to the desflurane non-delirium group. Conversely, in patients with POD, no significant EEG differences were observed between the sevoflurane and desflurane delirium groups. For the sevoflurane-induced patients, the sevoflurane delirium group had significantly lower power within 7.5–31.5 Hz (99.5% CI bootstrap analysis), reduced coherence over 8.9–23.8 Hz (99.5% CI bootstrap analysis), and lower PPC values in the alpha band (p < 0.005) compared with the sevoflurane non-delirium group. For the desflurane-induced patients, there were no significant differences in the EEG patterns between delirium and non-delirium groups. ConclusionsIn normal patients without POD, sevoflurane demonstrates a higher power spectrum and prefrontal connectivity than desflurane. Furthermore, reduced frontal alpha power, coherence, and connectivity of intraoperative EEG could be associated with an increased risk of POD. These intraoperative EEG characteristics associated with POD are more noticeable in sevoflurane-induced anesthesia than in desflurane-induced anesthesia.

Sensory-Processing Sensitivity Is Associated with Increased Neural Entropy.

This study aimed at answering the following research questions: (1) Does the self-reported level of sensory-processing sensitivity (SPS) correlate with complexity, or criticality features of the electroencephalogram (EEG)? (2) Are there significant EEG differences comparing individuals with high and low levels of SPS? One hundred fifteen participants were measured with 64-channel EEG during a task-free resting state. The data were analyzed using criticality theory tools (detrended fluctuation analysis, neuronal avalanche analysis) and complexity measures (sample entropy, Higuchi's fractal dimension). Correlations with the 'Highly Sensitive Person Scale' (HSPS-G) scores were determined. Then, the cohort's lowest and the highest 30% were contrasted as opposites. EEG features were compared between the two groups by applying a Wilcoxon signed-rank test. During resting with eyes open, HSPS-G scores correlated significantly positively with the sample entropy and Higuchi's fractal dimension (Spearman's ρ = 0.22, p < 0.05). The highly sensitive group revealed higher sample entropy values (1.83 ± 0.10 vs. 1.77 ± 0.13, p = 0.031). The increased sample entropy in the highly sensitive group was most pronounced in the central, temporal, and parietal regions. For the first time, neurophysiological complexity features associated with SPS during a task-free resting state were demonstrated. Evidence is provided that neural processes differ between low- and highly-sensitive persons, whereby the latter displayed increased neural entropy. The findings support the central theoretical assumption of enhanced information processing and could be important for developing biomarkers for clinical diagnostics.

Cortical mechanisms of sensory trick in cervical dystonia

Patients with cervical dystonia (CD) often show an improvement in dystonic posture after sensory trick (ST), though the mechanisms underlying ST remain unclear. In this study, we aimed to investigate the effects of ST on cortical activity in patients with CD and to explore the contribution of motor and sensory components to ST mechanisms. To this purpose, we studied 15 CD patients with clinically effective ST, 17 without ST, and 14 healthy controls (HCs) who mimicked the ST. We used electroencephalographic (EEG) recordings and electromyography (EMG) data from bilateral sternocleidomastoid (SCM) muscles. We compared ST-related EEG spectral changes from sensorimotor and posterior parietal areas and EMG power changes between groups. To better understand the contribution of motor and sensory components to ST, we tested EEG and EMG correlates of three different conditions mimicking ST, the first without skin touch (“no touch” condition), the second without voluntary movements (“passive” condition), and finally without arm movements (“examiner touch” condition).Results showed ST-related alpha desynchronization in the sensorimotor cortex and theta desynchronization in the sensorimotor and posterior parietal cortex. Both spectral changes were more significant during maneuver execution in CD patients with ST than in CD patients without ST and HCs who mimicked the ST. Differently, the “no touch”, “passive”, or “examiner touch” conditions did not show significant differences in EEG or EMG changes determined by ST execution/mimicking between CD patients with or without ST. A higher desynchronization within alpha and theta bands in the sensorimotor and posterior parietal areas correlated with a more significant activity decrease in the contralateral SCM muscle, Findings from this study suggest that ST-related changes in the activity of sensorimotor and posterior parietal areas may restore dystonic posture and that both motor and sensory components contribute to the ST effect.

Cognitive, sleep, and neurophysiological markers among suicidal depressed patients

Background Depressive disorders are associated with the highest probability of suicide. Different cognitive factors raise the probability of suicide. Sleep disorders are closely related to depression and may play a role in suicide. Aims Evaluation of whether suicidal depressed patients reveals distinct signs of cognitive, sleep, and neurophysiologic damage compared with depressed people who are not suicidal. Settings and design A case–control study involving suicidal depressed patients and non-suicidal in comparison to the control group. Patients and methods A random collection of 120 participants, who were divided into three groups at a ratio of 1:1:1 to be subjected to structured clinical interview for DSM-5(SCID-I), Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment scale (MoCA), Hamilton Depression Rating Scale (HDRS), Beck Scale for Suicidal Ideation (BSSI), Epworth Sleepiness Scale (ESS), and Standard Electroencephalogram (EEG). Statistical analysis SPSS, version 22, for analysis of data. Results Cognitive impairment, especially attention, language, visuospatial, naming, abstract thinking, and sleep disorders were significantly higher in suicidal depressed patients than in non-suicidal depressed patients and control. EEG shows no significant difference among the groups. Conclusion Suicidal depressed patients had significant impairment in different cognitive domains and sleep but no significant difference in EEG compared with non-suicidal depressed patients or control.

Electroencephalogram activity in attention-deficit hyperactivity disorder

ObjectiveThe aim of the study was to apply an evidence-based pharmacotherapy on different groups of attention-deficit hyperactivity disorder (ADHD) patients monitored by electroencephalogram (EEG) before and after 6 months of treatment and to estimate the prevalence of ADHD in a sample of Egyptian governorates (Kafr El Sheik and Menoufia neuropsychiatric clinics). It also aimed to detect the neurobiological basis of ADHD children using EEG.BackgroundADHD is one of the most commonly diagnosed and treated psychiatric disorders in childhood.Patients and methodA randomized, clinical trial was conducted on 30 children attending our neuropsychiatric outpatient clinic, screened from 255 children diagnostic through Diagnostic and statistical manual of mental disorders, 5th ed. and Kiddie-Schedule For Affective Disorders And Schizophrenia-Present And Lifetime Version. Psychiatry, Mental Health, (KSADS-PL) scale screening. Then the patients were divided into two equal groups. The first group received the drug Strattera (Eli Lilly Company) at a dose of (0.5: 1.2 mg/kg/day) only. The second group received Concerta (Alza Corporation) at a dose of (18 mg/day). Another 30 children are randomly allocated to control groups (30 children in each). Full history taking and complete clinical examination were done. KSADS-PL rating scale was assessed at baseline and then 6 months after treatment. EEG monitoring of children before and after treatment.ResultsIn this study we found that the score of the KSADS-PL rating scale was significantly decreased in ADHD patients after treatment in both pharmacotherapy groups. In addition, there was no significant difference in EEG between both ADHD children before and after treatment.ConclusionPharmacotherapy using drugs as concerta and stratera has beneficial effects in reducing ADHD symptom severity

Elderly patients with nonconvulsive status epilepticus: Clinical-EEG data, hospital mortality, STESS and EMSE

Purpose To assess the clinical-EEG aspects, characterization of subtypes, relationships with prognostic scales and the occurrence of death in elderly patients in the acute phase of nonconvulsive status epilepticus (NCSE).Methodology Clinical variables, EEG data, Status epilepticus severity score (STESS), and the Epidemiology-based mortality score in status epilepticus (EMSE) were related to the death of 96 patients who were over 60 years old, with NCSE.Results NCSE with coma was observed in 31 patients (19 non-subtle and 12 “subtle” SE) and focal NCSE with impairment of consciousness in 65 cases. There were no significant EEG differences according to the type of NCSE. Higher STESS scores occurred in the comatose NCSE patients when compared to those with focal NCSE and impairment of consciousness (4.8 ± 1.2 vs 3.7 ± 1.2; T-Test; p<0.001). It was observed that 25 (26%) elderly died, with a mean survival time of 19.3 days. Elderly people with a higher risk of death are those diagnosed with NCSE with coma (HR 2.76; 95% CI 1.15–6.65; p = 0.023), with STESS≥3 (HR 16.0; CI 1.77–45.08; p = 0.014), with EMSE≥64 (HR 3.67; CI 1.54–8.72; p = 0.003), and those with no history of recurrent SE (HR 6.80; CI 1.42–32.64; p = 0.017), in Cox regression.Conclusion The ictal EEG patterns did not distinguish the subtypes of NCSE. Thirty-day mortality rate was high in elderly patients with NCSE. The clinical variables are related to prognosis. Mortality in the elderly was associated with comatose NCSE patients, with STESS≥3, with EMSE≥64, and no history of recurrent SE.

DSM-5 Adult Attention-Deficit/Hyperactivity Disorder: Sex Differences in EEG Activity.

This study examined sex differences in the EEG of adults diagnosed with Attention-Deficit/Hyperactivity Disorder (AD/HD) according to DSM-5 criteria. Sixteen females and 16 males with AD/HD, and age- and sex-matched control groups, had an eyes-closed resting EEG recorded from 19 electrode sites. EEGs were Fast Fourier transformed and estimates for total power, absolute and relative power in the delta, theta, alpha, beta and gamma bands, and the theta/beta ratio, were analysed across nine cortical regions. Males with AD/HD, compared with male controls, had globally reduced absolute beta, globally elevated relative theta, and a larger theta/beta ratio. In contrast, no global effects emerged between females with and without AD/HD. Significant group interactions indicated that globally elevated relative theta and elevated frontal-midline theta/beta ratio noted in males with AD/HD differed significantly from results in females. There are statistically significant EEG differences in relative theta and the theta/beta ratio between males and females with and without AD/HD. These results indicate that AD/HD affects the EEG activity of males and females differently. This study helps confirm the need for further independent examination of AD/HD within female populations.

Test-retest reliability of the virtual reality sickness evaluation using electroencephalography (EEG)

No reliable quantitative and objective measurement method for virtual reality (VR) sickness has been firmly established to date. Electroencephalography (EEG) may be a strong candidate to evaluate VR sickness objectively. However, no test-retest evaluation has been made for VR sickness using EEG. To recruit VR sickness-sensitive participants, we tested 858 participants (age = 20′s–50′s) using the Motion Sickness Susceptibility Questionnaire (MSSQ). Among them, we recruited 21 males (average age = 25.0) who obtained the 75th percentile of scores on the MSSQ (32.9 ± 5.7). VR sickness was evaluated twice (one week apart) using EEG with VR video content designed to cause VR sickness. A Simulation Sickness Questionnaire (SSQ) was also used to evaluate VR sickness. In terms of the reliability of EEG, ICC and Cronbach’s alpha analyses showed that three waves (delta, theta, and alpha) were consistent in two areas (frontal and central). A significant difference in EEG was also found repeatedly between the baseline and VR sickness (delta, theta, and alpha) in two areas (frontal and central). We evaluated EEG for its reliability and found specific waves and areas that showed good consistency and significant changes associated with VR sickness. These findings may support further research of VR sickness evaluation.

1406 – Does the communication beyond five sensory modalities exist in SD rats?

Objective To demonstrate whether the communication between two SD rats base on the similar genetic basis or the same living environment, who separated (including visual, auditory, tactile, olfactory and tasting inputs)from each other, occurs. Methods One SD rat (RECEIVER) was examined by EEG spectral analysis and ECG analysis under anesthesia while the other SD rat (SENDER) received optimal stimuli or malignant stimuli. The course was conducted in the shielded and the unshielded. Compare the EEG and ECG of RECEIVER between the stimulation state and resting state of SENDER. Results This study show no significant difference in EEG (index: percentile weight and average weight of EEG on frontal lobe, temporal lobe, hippocampus of each frequency band) and ECG (index: R, PR segment, ST segment, QRS segment, QT segment) of RECEIVER during the time that the SENDER suffered from malignant stimulation, experienced optimal stimulation and of resting state. Conclusion The communication of SD rats, not through common five sense organ may not exist, even though the same genetic basis or the common living surrounding.The optimal stimuli and the malignant stimuli of SENDER cannot influence the EEG of Frontal lobe, temporal lobe, hippocampus and ECG on RECEIVER. There is no sufficient evidence for the existence of this communication of animal.

EEG Activity of Men and Women with DSM-5 Adult AD/HD

Event Abstract Back to Event EEG Activity of Men and Women with DSM-5 Adult AD/HD Franca Dupuy1, 2*, Adam R. Clarke1, 2, Robert J. Barry1, 2, Rory McCarthy3 and Mark Selikowitz3 1 University of Wollongong, School of Psychology, Australia 2 Centre for Psychophysics, Psychophysiology, and Psychopharmacology, Australia 3 Sydney Developmental Clinic, Australia Aims: Despite knowledge that AD/HD often persists into adulthood, there have been minimal investigations of the EEG activity of adults with AD/HD. This study aimed to explore the EEG activity of adult males and females who were initially diagnosed with AD/HD as children, and then reassessed, as unmedicated adults, using the new DSM-5 criteria. A secondary aim of this study was to explore gamma power within this population. Method: Participants included 16 females and 16 males with AD/HD, and sex-matched control groups. A five minute eyes-closed resting EEG was recorded from 19 electrode sites. The EEGs were Fast Fourier transformed and estimates for total power, absolute and relative power in the delta, theta, alpha, beta and gamma bands, and the theta/beta ratio, were analysed in nine cortical regions. Results: Males with AD/HD, compared with male controls, had globally reduced absolute beta, globally elevated relative theta, and a larger theta/beta ratio. In contrast, no global effects emerged between females with and without AD/HD. Significant sex by group interactions found that globally elevated relative theta and elevated frontal-midline theta/beta ratio noted in males with AD/HD differed significantly from results in females. Also, relative to male controls, males with AD/HD had reduced posterior absolute gamma activity. No significant gamma differences were found between women with and without AD/HD. Conclusions: There are statistically significant EEG differences in relative theta and the theta/beta ratio between males and females with and without AD/HD. These results indicate that AD/HD affects the EEG activity of males and females differently. The male gamma findings are similar to findings reported in children with AD/HD, suggesting a continuing gamma deficit in males with AD/HD, but not in females. Keywords: Attention-Deficit/Hyperactivity Disorder, adults, DSM-5, EEG, sex differences Conference: ASP2013 - 23rd Annual meeting of the Australasian Society for Psychophysiology, Wollongong, Australia, 20 Nov - 22 Nov, 2013. Presentation Type: Oral Presentation Topic: Other... Citation: Dupuy F, Clarke AR, Barry RJ, McCarthy R and Selikowitz M (2013). EEG Activity of Men and Women with DSM-5 Adult AD/HD. Conference Abstract: ASP2013 - 23rd Annual meeting of the Australasian Society for Psychophysiology. doi: 10.3389/conf.fnhum.2013.213.00019 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 24 Oct 2013; Published Online: 05 Nov 2013. * Correspondence: Ms. Franca Dupuy, University of Wollongong, School of Psychology, Wollongong, NSW, 2522, Australia, fdupuy@uow.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Franca Dupuy Adam R Clarke Robert J Barry Rory McCarthy Mark Selikowitz Google Franca Dupuy Adam R Clarke Robert J Barry Rory McCarthy Mark Selikowitz Google Scholar Franca Dupuy Adam R Clarke Robert J Barry Rory McCarthy Mark Selikowitz PubMed Franca Dupuy Adam R Clarke Robert J Barry Rory McCarthy Mark Selikowitz Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

A review of EEG and ERP studies in bipolar disorder

Objective:The electroencephalogram (EEG) can be a useful tool in determining differences in general neural activity and specific waveforms in individuals with a number of psychiatric disorders. This paper aims to outline and discuss significant findings in EEG and event-related potential (ERP) research into bipolar disorder (BD).Methods:A literature review was performed through searches of MedLine, EMBASE, CINAHL and PsycInfo medical research databases for papers published from 1985 onwards. References of selected articles were also examined for other relevant studies.Results:Differences in general EEG data were found in subjects with BD, namely increased theta and delta and decreased alpha wave bands. Changes in EEG were also found in euthymic BD subjects and those undergoing medication programmes. ERP studies commonly report prolonged latencies and reduced amplitudes in the P300 component. Hyperfunctioning of the right hemisphere in BD was also reported in some studies, although further confirmation of this finding is required. Finally, the effects of medication and the role that genetics plays in EEG still remain unclear.Conclusions:The literature reviewed demonstrates supporting evidence for the presence of significant differences in EEG and ERP data in subjects with BD. However, methodological considerations such as varying mood states and medication status of the patients need to be followed more stringently for future research to bring about a robust model of the cognitive deficits of BD.

EEG?mapping differences between narcolepsy patients and controls and subsequent double?blind, placebo?controlled studies with modafinil

The aim of the present study was to investigate the role of EEG mapping as an objective and quantitative measure of vigilance in untreated and modafinil-treated narcoleptics, and compare it with the conventional neurophysiological method of the Multiple Sleep Latency Test (MSLT) and the subjective Epworth Sleepiness Scale (ESS). In 16 drug-free narcoleptics and 16 normal controls a baseline 3-min vigilance-controlled EEG (V-EEG) and a 4-min resting EEG (R-EEG) were recorded during midmorning hours. Thereafter, in a double-blind, placebo-controlled crossover design, patients were treated with a 3-week fixed titration of modafinil (200, 300, 400 mg) and placebo. EEG-mapping, MSLT and ESS measures were obtained before and at the end of the third week of therapy. Statistical overall analysis by means of the omnibus significance test demonstrated significant EEG differences between untreated patients and controls in the resting condition only (R-EEG). Subsequent univariate analysis revealed an increase in absolute and relative theta power, a decrease in alpha-2 and beta power as well as a slowing of the dominant frequency and the centroids of the alpha, beta and total power spectrum and thus objectified a vigilance decrement in narcolepsy. Modafinil 400 mg/d significantly improved vigilance as compared with placebo (p < or = 0.01), inducing changes opposite to the aforementioned baseline differences (key-lock principle). The MSLT and the ESS also improved under modafinil as compared with placebo, but changes were less consistent. Spearman rank correlations revealed the highest correlations between EEG mapping and the ESS, followed by those between EEG mapping and the MSLT, while the lowest correlation was found between the MSLT and the ESS. In conclusion, EEG mapping is a valuable instrument for measuring vigilance decrements in narcolepsy and their improvement under psychostimulant treatment.

Patterns of EEG coherence, power, and contingent negative variation characterize the integration of transcendental and waking states

Long-term meditating subjects report that transcendental experiences (TE), which first occurred during their Transcendental Meditation (TM) practice, now subjectively co-exist with waking and sleeping states. To investigate neurophysiological correlates of this integrated state, we recorded EEG in these subjects and in two comparison groups during simple and choice contingent negative variation (CNV) tasks. In individuals reporting the integration of the transcendent with waking and sleeping, CNV was higher in simple but lower in choice trials, and 6–12 Hz EEG amplitude and broadband frontal EEG coherence were higher during choice trials. Increased EEG amplitude and coherence, characteristic of TM practice, appeared to become a stable EEG trait during CNV tasks in these subjects. These significant EEG differences may underlie the inverse patterns in CNV amplitude seen between groups. An ‘Integration Scale,’ constructed from these cortical measures, may characterize the transformation in brain dynamics corresponding to increasing integration of the transcendent with waking and sleeping.

Neonatal Nicotine Exposure Alters Hippocampal EEG and Event-Related Potentials (ERPs) in Rats

A consensus is forming that nicotine can damage the developing rat central nervous system. However, few studies have assessed the electrophysiological effects of neonatal nicotine exposure in rodents in brain regions known to be sensitive to the teratogenic properties of nicotine. In a previous study it was reported that 1.0 and 4.0 mg/kg/day nicotine exposure from postnatal days 4–9, a developmental period corresponding to human third-trimester exposure, significantly altered hippocampal event-related potentials (ERPs) but did not effect cortical ERPs, cortical EEG, or hippocampal EEG. Because alterations in behavior and cortical/hippocampal neurochemistry and morphology have been reported following nicotine exposure, the present study used a higher dose of nicotine during the postnatal period (6.0 mg/kg/day) determine if functional changes in the EEG of these regions might contribute to behavioral changes that have been observed. Male Sprague–Dawley rats were exposed to 6.0 mg/kg/day nicotine via gastric infusion using an artificial rearing, “pup-in-the-cup,” technique for 6 consecutive days (postnatal days 4–9). At adulthood, EEG and auditory ERPs were recorded from the cortex and hippocampus. There were no significant differences in EEG or ERPs recorded from the cortex between nicotine-treated and control subjects. Examination of the hippocampal EEG revealed significantly decreased power in the 1–2-Hz frequency band of nicotine-treated rats. In addition, there was a significantly attenuated P300 ERP response to a noise tone in the nicotine-treated rats compared to controls. These data indicate that neonatal nicotine exposure alters functional activity in the hippocampus of adult rats. These effects are likely to be the result of synaptic disorganization in the hippocampus, and indicate that neonatal nicotine exposure exerts teratogenic effects on the developing central nervous system, particularly the hippocampus, which persist into adulthood.

Electrocortical signs of arousal in response to darkness and the assessment of Type A behavior in professional drivers with and without cardiovascular disease.

In night driving, the fatal accident rate is about four times that in daytime. There is a lack of published studies of the effect of darkness on electrocortical responses in professional drivers (PD). Assessing relations between electroencephalographic (EEG) reactions to enforced darkness reminiscent of night driving, and untoward behavioral response patterns, notably Type A behavior. PD: 13 with ischemic heart disease, 12 hypertensives (HTN), 10 borderline hypertensives and 34 normotensives, and 23 non-PD controls. Five minutes of electroencephalographic recording with eyes closed, and subsequently 3 minutes exposure to darkness. EEG parameters were: alpha abundance, amplitude and frequent. Type A behavior (TAB) was assessed by observation and by questionnaire. Alpha abundance diminished significantly for darkness compared to spontaneous recording for all groups. No between-group differences were found for EEG. There were no significant differences in EEG between drivers with IHD or HTN taking versus not taking centrally active beta-blockers. Drivers with IHD were the only group to show significant increase in dominant alpha frequency at darkness. The IHD group also had the highest TAB questionnaire scores and the heaviest exposure to professional driving. Type A scores were significantly correlated with dominant alpha frequency during darkness. Low availability of attachment and special driving hazards best predicted TAB scores in driven. There was a significance between group difference with respect to Symbolic Aversiveness at the work place comparing each driver group with the non-PD control group. Exposure to darkness reminiscent of night driving can elicit central arousal, in conflict with circadian rhythm, and in combination with other driving hazards which contribute to symbolic aversiveness, the essence of driving. And low availability of social attachment could contribute to sustained arousal, and in turn to the development of Type A behavior in professional drivers.

Postictal Psychiatric Events During Prolonged Video-Electroencephalographic Monitoring Studies

Postictal psychiatric events presenting as postictal psychotic events and postictal nonpsychotic events are known to occur following seizure clusters. Accordingly, patients undergoing prolonged video-electroencephalographic (EEG) monitoring studies may be at increased risk of experiencing postictal psychiatric event, as they often have flurries of seizures during these studies. To determine the annual incidence and clinical characteristics of postictal psychotic events and postictal nonpsychotic events in video-EEG monitoring studies in patients with partial seizure disorders and to identify potential pathogenic factors. Thirteen patients met the criteria for a postictal psychiatric event during the 18-month study period, 10 presenting as postictal psychotic events and three as postictal nonpsychotic events. The annual incidence of postictal psychiatric events at our monitoring unit for 1988 was 7.8%, 6.4% presenting as postictal psychotic events and 1.4% as postictal nonpsychotic events. Seven patients had their first-ever postictal psychiatric event during the monitoring study. In 12 of the 13 patients, the postictal psychiatric events mimicked well-defined psychiatric entities of shorter duration (mean, 66.5 hours); they appeared 12 to 72 hours after the last seizure and remitted spontaneously or with the use of low-dose psychotropic medication. No significant differences in EEG, neuroradiologic, psychiatric, medical, or psychosocial data were found between the patients with postictal psychiatric events and a group of 13 age-matched control patients. Follow-up data of comparable duration were available in nine patients with postictal psychiatric events and nine controls. Psychiatric events were reported more frequently by patients with postictal psychiatric events than by control patients (P=.03). In three patients, postictal psychiatric events converted to interictal events. These findings suggest that monitoring studies increase the risk for postictal psychiatric events, which neurologists need to be familiar with, as they represent important morbidity associated with these studies.

Brain Electrical Imaging the Dose-Response Effects of Cigarette Smoking

Quantitative regional electroencephalographic (EEG) effects of cigarette smoking were examined within a repeated measures design which assessed, and topographically displayed, changes in power spectral estimates resulting from the smoking of low, medium and high tar/nicotine (T/N) yield cigarettes. Although intercigarette yield comparisons revealed no significant EEG differences between yields, comparison of the effects of smoking each yield with sham smoking indicated the presence of a qualitative dose-response effect whereby increasing T/N yields resulted in a progressive posterior-to-anterior spreading of significant relative power changes within both theta and alpha frequency bands. These exploratory findings are discussed in relation to smoking maintenance and working hypotheses are formulated for future testing.

Treatment of acute focal cerebral ischemia with dimethyl sulfoxide.

The object of this investigation was to study the effects of dimethyl sulfoxide (DMSO) upon the evolution of cerebral infarction. Twenty adult cats anesthetized lightly with ketamine hydrochloride underwent right middle cerebral artery occlusion for 6 hours. Ten cats were not treated and 10 cats received DMSO (2.5 g/kg i.v.) immediately after occlusion. Regional cerebral blood flow (rCBF) changes in the right sylvian region were similar in the untreated and treated groups. The mean rCBF before occlusion was 46 +/- 10 ml/100 g/minute in the untreated group and 45 +/- 10 ml/100 g/minute in the treated group. Eight cats in both groups had rCBF measurements consistently below 18 ml/100 g/minute during the 6-hour period after occlusion. An index of erythrocyte flow was determined by measuring the transit of technetium-99 (99Tc)-labeled erythrocytes in the right sylvian region. The period of erythrocyte transit before occlusion was 10 +/- 1 seconds in the untreated group and 10 +/- 2 seconds in the treated group. After 6 hours of occlusion, the erythrocyte transit time was 18 +/- 3 seconds in the untreated group and 19 +/- 3 seconds in the treated group. Increasing delay in erythrocyte transit during the 6-hour occlusion period was seen in 5 untreated cats and 6 treated cats and was thought to represent a progressive increase in microvascular resistance. The complete washout of erythrocytes indicated the absence of microcirculatory obstruction. Electroencephalography (EEG) showed a reduced amplitude of activity in the right cerebral hemisphere after occlusion in cats with an rCBF consistently below 18 ml/100 g/minute. No significant EEG differences were found between the untreated and treated groups. Treatment with DMSO failed to modify the developing ischemia edema, neuronal alterations, or the changes in blood-brain barrier permeability to Evans blue dye and fluorescein. In this study DMSO was ineffective in preventing ischemic damage or acted when irreversible injury had already taken place.

Contribution of the speech musculature to apparent human EEG asymmetries prior to vocalization

Vocalizations are preceded by slow EEG waves over inferior frontal scalp regions, but some controversy exists as to whether these slow potentials are left-lateralized as a function of speech. In this study both speech and non-speech vocalizations were studied, under conditions of repetitive and variable production. Averaged responses over the speech musculature, including the temporalis, masseter, orbicularis oris, and mylohyoid muscles, as well as the eyes and tongue, were calculated simultaneously with scalp EEG averages. The responses of the temporalis and masseter muscles, as well as that of the tongue, were correlated with EEG sites at specific latencies prior to speech, suggesting that no part of the inferior frontal EEG record was free from myogenic confounds. In addition, all significant EEG differences between speech and non-speech conditions were subsequently eliminated by covariance analysis, using selected muscle channels as covariates. Previous reports of asymmetrical “speech potentials” in the EEG probably reflected a combination of several myogenic confounds.

Hippocampal EEG and behaviour in dog. III. Hippocampal EEG correlates of stimulus-response tasks and of sexual behaviour

A dog was trained to perform a spatial sound discrimination. The hippocampal EEG correlates and the movement correlates of correct trials were compared with those of incorrect trials and of ‘pressings in between’. Correct and wrong responses on a place learning task were compared both with respect to the hippocampal EEG correlates and to the motor behaviour. Where significant differences in EEG correlates were found, the motor behaviour differed significantly as well. The same was found for 2 behavioural states with different motor behavioural qualities which occurred during copulation. The data support the hypothesis that the spectral properties of the hippocampal EEG reflect in a predictable but non-specific way the intensity of motor behaviour. They question the postulated correlations between hippocampal EEG and ‘internal processes’, on the ground that unambigous experimental verification of such hypothesis appears to be very difficult.