Hemispheric lateralization of EEG in early infantile autism

Autoregressive (AR) analysis and component analysis were applied to EEGs during sleep stage 2 of normal and autistic children, since AR-coefficients of EEG characterize the autocovariance and power spectral density of EEG. In addition, as the Mahalanobis' generalized distance of the average AR coefficient vector of an EEG group at one side from that at the opposite side follows a F-distribution, the statistical inferences were carried out, whether or not there is hemispheric specialization in EEG in 21 right handed autistic children and whether there is difference between AR-spectral pattern of EEG in the autistic children and that of 28 normal children of the same age range or not. The results obtained were as follows: 1) The significant hemispheric lateralization in EEG at the significant level of 0.01 was observed in normals, whereas none of the lateralization was confirmed in autistic children. 2) The random click stimulation caused a cumulative effect on the hemispheric lateralization in the normals, but not in the autistic children. On the contrary, the effects of random flash light stimulation on hemispheric asymmetry were verified in the autistic children as well as in the normals. 3) The EEG components of autistic children were significantly different from the normal ones in frequency range of alpha-2 component wave at bilateral frontal (F1 and F2) regions and the activity of these component waves were higher in the autistic children than in the normal ones over 5 years-old. 4) These findings suggest that autistic children are not only less responsive to external stimuli, but also neurophysiologically less active in the internal regulatory mechanism.     

Clustering of sleep electroencephalographic patterns in patients with the fibromyalgia syndrome

Several electroencephalographic (EEG) abnormalities have been observed during sleep in patients suffering from the fibromyalgia syndrome (FMS). In this study, 12 patients with fibromyalgia and 14 control subjects had two polysomnographic recordings obtained at home. Data from the second night were subjected to blinded manual scoring as well as signal processing using linked or 'step-wise clustering for pattern recognition. In this procedure, a common learning set was generated using the spectral information in three 2 min EEG samples from each of the sleep stages selected from five patients with FMS and five controls. In this way, 17 characteristic EEG classes were defined. All 2 s EEG segments from the whole night from all subjects were then assigned to one of these classes. Five of the classes (dominated by 0.5-4.5 Hz activity) were more frequent in the control group, whereas three other classes (dominated by 8-11 Hz activity) were prevalent in the patient group. This trend was consistent in all sleep stages, although most striking in non-rapid eye movement (NREM) sleep. The predominance of these classes in the patient group may correspond to the alpha-EEG sleep anomaly previously reported in subjects with FMS. More importantly, as the EEG power in the lowest frequency range (prevalent in controls) probably is a marker for restorative sleep, the findings may reflect important aspects of sleep disturbances n subjects suffering from FMS, thereby contributing to some of the daytime symptoms in these patients.     

Topographical analysis of the EEG effects of a subconvulsive dose of lidocaine in healthy volunteers

BACKGROUND: The purpose of the present study was to assess the effects of intravenous lidocaine on spatial changes of electroencephalographic power and on psychomotoric status in conscious volunteers. METHODS: In 11 healthy volunteers lidocaine (2-min bolus, 100 mg; 15 min infusion, 40 micrograms.kg-1.min-1) or placebo were given intravenously in a randomized, single-blinded, two-way crossover study. Haemodynamics and lidocaine plasma concentrations were measured at baseline and within a period of 30 min following bolus injection. Vigilance and emotional status were tested using visual analogue scales (VAS). Toxic CNS effects were evaluated by a questionnaire. The raw EEG (17 leads, reference Cz) and computed power spectra were continuously recorded. RESULTS: The chosen lidocaine dosage led to nearly constant plasma concentrations (unbound lidocaine 2.5 min and 15 min after bolus 0.36 +/- 0.14 microgram/ml and 0.30 +/- 0.06 microgram/ml, respectively [mean +/- SD]). The placebo caused no symptoms, changes in VAS-scores or EEG-parameters. Lidocaine induced pronounced subjective symptoms and significant increases in delta activity for 15 min, most dominant at the frontotemporal and occipital leads (max. +219% O1). Frontal and occipital beta 1 and beta 2 power (max. +131% and +124% at O1, respectively) was immediately increased after the bolus injection. No EEG changes occurred at central region Cz, and no interhemispheric EEG differences were noted. Theta, alpha 1, and alpha 2 power remained unchanged. CONCLUSION: The current data demonstrate simultaneous changes in psychomotoric status as well as delta and beta spectral power during lidocaine infusion. These data could be an indication that the pronounced frontotemporal and occipital EEG changes are the electroencephalographic expression of subjective sensations.     

Sleep and EEG power spectrum effects of the 5-HT1A antagonist NAN-190 alone and in combination with citalopram

The sleep and waking and EEG power spectrum effects of the putative 5-HT1A antagonist NAN-190 (0.5 mg/kg, i.p.) were studied alone and in co-administration with the selective serotonin re-uptake inhibitor citalopram (5.0 mg/kg, i.p.) in the rat. Citalopram, as in a prior dose-response study, reduced REM sleep. In addition, a slight increase in NREM sleep was observed. Citalopram reduced NREM fronto-parietal (FP) EEG power density in the 5-20 Hz range. When administered alone, NAN-190 suppressed REM sleep in the first 2 h, and reduced SWS-2 in the first 4 after administration. NAN-190 also suppressed selectively NREM sleep slow-wave activity in both fronto-frontal (FF) and FP EEG power spectrum. When administered in combination with citalopram, an attenuation of the power density reduction in the 7-15 Hz range in the FF EEG of citalopram alone, was observed. However, the EEG power spectral density and REM sleep suppressive effects of NAN-190 were both augmented. The results are compatible with the notion that serotonin is involved in the modulation of the slow wave activity in the EEG during NREM sleep. The results are cordant with other data suggesting that postsynaptic 5-HT1A stimulation might increase slow wave activity in the NREM EEG, and that serotonergic stimulation of other receptor subtypes (possibly 5-HT2) may decrease slow wave activity in the NREM EEG.     

Initial experience with the Cordis stent: analysis of serial angiographic follow-up

Studies were carried out on 150 workers with mental disturbances, who had been involved in the clean-up of the Chernobyl atomic energy station accident. Visual and computer analyses of EEG traces from 43 workers were compared with traces from 17 healthy subjects, and the comparison revealed that the most common features in workers were disorganization of the alpha-rhythm and strengthening of beta-1-activity in the sensorimotor cortex. In neurosis-like syndromes (13 patients), there was a significant increase in the power of the alpha-rhythm in the anterior parts of the cortex; in psycho-organic states, power as significantly reduced (especially in the left hemisphere). Contributing to the greater proportion of flat EEG traces in patients with psycho-organic syndromes as compared with other groups of patients. Most patients among the clean-up workers had increased assimilation of flashing light rhythms and weakening of non-specific and skin galvanic responses to a light stimulus. It was concluded that systemic CNS changes occurred in patients from the clean-up worker groups, especially in those with psycho-organic syndrome.     

Individual differences in anterior brain asymmetry and fundamental dimensions of emotion.

Assessed whether individual differences in anterior brain asymmetry are linked to differences in basic dimensions of emotion. In each of 2 experimental sessions, separated by 3 wks, resting EEG activity was recorded from female adults during 8 60-sec baselines. Mean alpha power asymmetry across both sessions was extracted in mid-frontal and anterior temporal sites. Across both regions, groups demonstrating stable and extreme relative left anterior activation reported increased generalized positive affect (PAF) and decreased generalized negative affect (NAF) compared with groups demonstrating stable and extreme relative right anterior activation. Additional correlational analyses revealed robust relations between anterior asymmetry and PAF and NAF, particularly among Ss who demonstrated stable patterns of EEG activation over time. Anterior asymmetry was unrelated to individual differences in generalized reactivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brain biopotential mapping in emotional and cognitive pathology

The EEG rhythms spectral power and intracortical connections were studied in depressive and schizophrenic patients in four schematically outlined main cortical quadrants. In depressive patients two cortical quadrants--right anterior and left posterior ones appeared to be predominantly involved in negative emotions regulation. Alpha-rhythm spectral power and cortical connections in these areas were decreased, pointing to their relative hyperactivation and functional disturbances. Schizophrenics patients were divided into two groups--with the predominance of "positive" and "negative" symptoms. In the first group there was revealed the decrease of the most EEG rhythms spectral power only in parietal areas, on the second one--in all cortical areas. There was also the significant alpha-rhythm spectral power asymmetry, different in the two groups of schizophrenic patients. In "positive" schizophrenics the decrease of alpha-rhythm spectral power was revealed in parietal and occipital areas of the right hemisphere, and in "negative" ones--vice versa, these results pointing of the relatively higher activation of the right posterior quadrant in the former group and of the left posterior quadrant in the latter one. In the anterior cortical quadrants the intracortical connections were however higher in the left hemisphere in "positive" and in the right one--in "negative" schizophrenics. Thus, there are some contradictory results obtained by different methods in anterior and posterior cortical quadrants in each hemisphere, these results being of opposite directions in patients with "positive" and "negative" manifestations. "Region of interest" (ROI) in schizophrenics appeared to be predominantly the frontal and temporal ones, while the "Rhythm of interest"--beta2.     

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.     

Gallbladder diverticulum: a case report and review of the literature

BACKGROUND: The clinical significance of the 14 and 6 positive spikes (PS) electroencephalographic (EEG) phenomenon is not well established. This study was performed to provide further data regarding the clinical correlates of the PS, particularly attention-deficit/hyperactivity and somatic symptoms. METHODS: Diagnostic information gathered through structured interviews was compared among four groups of psychiatric inpatients aged 4-17 years who underwent an EEG examination over a 2-year period. Groups consisted of patients with: 1) 14 and 6 PS (n = 25); 2) epileptic discharges (n = 29); 3) slow-wave abnormalities (n = 23); and 4) a normal EEG group age and sex matched to the 14 and 6 PS group (n = 25). RESULTS: Attention-deficit hyperactivity disorder (ADHD) symptoms were significantly more frequent in the PS group (chi 2 = 2.96, p < .05) compared to the other three groups combined. Although somatic symptoms were not increased in the 14 and 6 PS group, anxiety symptoms tended to occur more in this group (chi 2 = 3.50, p < .06). CONCLUSIONS: The PS profile appears associated with ADHD symptoms. Possible treatment implications of this finding (e.g., use of anticonvulsants in ADHD patients with PS) need to be explored.     

Right atrial thrombi: percutaneous mechanical thrombectomy

Daytime sleepiness is an important symptom of obstructive sleep apnoea syndrome (OSAS). The standard tests for its objective quantification use EEG recordings, and are time consuming and expensive, which makes them difficult to use for large studies. This study assesses the ability of a simple test of sustained 'wakefulness' to discriminate the excessive somnolence of severe symptomatic obstructive sleep apnoea from normality, and compares its results to the traditional EEG based Maintenance of Wakefulness Test (MWT). Ten subjects (7M 3F) with severe sleep apnoea (> 4% SaO2 dip rate median 32.7 (90% central range 9.7-65.6)) and symptoms of daytime sleepiness, (Epworth Sleepiness Score (ESS)17(10-24)) and 10 normal subjects (4M 6F, ESS 3.5(1-8)) were studied. The MWT and the behavioural test (Oxford SLEep Resistance test - OSLER test) were performed on each subject in random order on 2 separate days. The protocol for both tests was the same with 4 X 40 min sleep resistance challenges throughout the day while sound isolated in a darkened room. During the OSLER test subjects were asked to press a switch in response to a light emitting diode (LED), which was lit for 1 s in every three. Both the switch and the light were connected to a computer that stored both the number of times the light was illuminated and whether a correct response was made. The OSLER test discriminated the normal subjects from the sleep apnoea group (mean sleep latency (min) normal group 39.8, OSA group 10.5) as well as the traditional MWT (normal group 38.1 OSA group 7.3) and was much simpler to administer. This test has the advantage that sleep onset is defined objectively and automatically as a failure to respond to the light, rather than from EEG interpretation, which is inevitable partly subjective. This technique may provide a simple and robust method of objectively quantifying daytime sleepiness for large studies.     

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.     

A field application of the ASAM placement criteria in a 12-step model of treatment for chemical dependency

Various CNS side effects have been reported since interferon (IFN) was introduced for the treatment of chronic active hepatitis C (CAHC) patients. Most reports of EEG changes after IFN therapy were inspective, and there is no report of quantitative EEG analysis. In this study, changes in quantitative EEG and biogenic amines after IFN therapy were studied to enable identification of CNS side effects early in CAHC patients. Before and 7 days after IFN therapy, EEG records and plasma and urinary amines were examined in 36 CAHC patients (46.9 +/- 12.3 years, 29 men and 7 women) who were hospitalized for the IFN therapy. After IFN therapy, no notable change in biogenic amines was recognized. On EEG, 13 patients (39.4%) showed increased slow wave activities and 2 patients (6.1%) showed paroxysmal discharges after IFN therapy. On quantitative EEG, the patients showed significantly increased absolute power in slow alpha, theta and delta bands and decreased absolute power in fast beta band (paired-T test). After IFN therapy, 4 of 36 patients developed psychiatric disorders; 2 patients developed depressive symptoms and 2 other patients developed manic states. One depressive patient and one manic patient had 6 Hz spike and slow waves before IFN therapy. On quantitative EEG, the other manic patient had shown significantly increased absolute power in slow alpha and decreased power in fast alpha and beta bands, and the other depressive patient had shown significantly increased absolute power in fast theta band and decreased power in fast beta band before the development of the psychiatric disorders. These results suggest that the changes of quantitative EEG, between before and 7 days after IFN therapy, can be useful in assessing the risk for the development of psychiatric symptoms induced by IFN therapy. It also suggests that patients with slight EEG abnormality such as a 6 Hz spike and slow waves before IFN therapy need careful observation.     

Effects of L-dopa and vitamin B6 on electroencephalograms of schizophrenic patients: a preliminary report

1. To assess the therapeutic effect of low-dose L-Dopa therapy and associated EEG changes in chronic schizophrenia, 10 patients with a mean duration of illness of 12.4 years were treated with L-Dopa for a period of eight weeks during which the dosage was increased progressively from an initial level of 300 mg q.d. biweekly up to 600 mg q.d. The treatment was moderately effective in one case and slightly efficacious in one, produced no significant change in the conditions of seven patients while the remaining patient showed exacerbation; hence a noticeably low rate of improvement. There occurred no significant changes in the EEG pattern in the series of 10 patients on the average. The individual patients' responses, nevertheless, could be classified into three groups: one with no observable EEG changes, the second showing a slight degree of increase in alpha activity and the third exhibiting diminution of alpha activity in the EEG. The patients in the latter two groups all had durations of disease less than 10 years. 2. Observations were made primarily of changes in the EEG in 20 chronically schizophrenic patients with a mean duration of disease of 13 years receiving 60 mg of vitamin B6 (as pyridoxal-5'-phosphate) daily over a period of four weeks. Slight increase of alpha activity and decrease of theta activity in the EEG were noted on the average of the 20 cases, in response to the vitamin B6 therapy. The increase of alpha activity was frequently seen among patients with a duration of illness less than 10 years whose pretreatment EEG pattern had been alpha dominant (five out of 10 cases), whereas a slight ameliorative tendency of EEG was observed only in one out of 10 patients whose pretreatment EEG pattern had been slow-wave dominant. Symptomatic improvement was evident only in one of the 20 cases studied. 3. Observations were made of the therapeutic effect and associated EEG changes in eight patients receiving combined medication of 200 mg L-Dopa and 30 mg vitamin B6 (as pyridoxal-5'-phosphate) daily for a period of 12 weeks. Of these eight patients with a mean duration of disease of 18.3 years, two showed excellent response, three good and three fair; hence good to excellent responses attained in five out of the eight cases or 62.5%. A marked increase in alpha activity in the EEG occurred from the 2nd to 4th weeks onward in all eight cases. The EEG changes were likely to precede the symptomatic improvement. 4. To sum up the results of these three clinical trials, administration of L-Dopa alone resulted in practically no symptomatic improvement or EEG changes in patients with chronic schizophrenia whilst vitamin B6 administered singly as pyridoxal-5'-phosphate scarcely produced significant symptomatic improvement but brought about a slight ameliorative tendency in the EEG of such patients. Both symptomatic amelioration and EEG improvement occurred following combined medication of L-Dopa and vitamin B6...     

Sex differences in EEG in adult gonadectomized rats before and after hormonal treatment

EEG activity was recorded from the left and right parietal cortex in adult male and female Wistar rats that were gonadectomized (GNX) after puberty during 2 days without and 3 days with hormonal treatment (either testosterone propionate, 5 alpha-DHT or vehicle in males and progesterone, estradiol benzoate or vehicle in females). In contrast to EEG characteristics reported for intact rats, GNX abolished right over left parietal activation in both sexes and, sex differences in EEG interhemispheric correlation and in theta and delta relative power in the right parietal; additionally GNX males showed higher absolute power than females. Hormonal treatment reestablished interparietal asymmetry in both sexes and a lack of sex differences in absolute power, however, it was not enough to reestablish sex differences in delta and theta proportion in the right parietal nor in interhemispheric correlation. Differential effects were obtained with testosterone propionate and 5 alpha-DHT in males suggesting that activational effects of testosterone on EEG are probably exerted through testosterone or its aromatized metabolites. The results of our study indicate that the activational effects of gonadal steroids after puberty are necessary for maintaining sex differences in the EEG of the adult rat.     

Inactivation of nitric oxide synthase isoforms by diaminoguanidine and NG-amino-L-arginine

We studied the value of long video-split electroencephalographic monitoring (VSEEG) in detecting myoclonus in nearly SSPE and evaluated the natural history and outcome-affecting factors. The 32 newly diagnosed patients had VSEEG to detect myoclonus and its correlations with EEG periodic complexes. Disease progression was monitored by a special "outcome score'; the chi-square test and multi-variable statistics analysed the outcome score in relation to different variables, such as age at onset, sex, duration of symptoms at presentation, CSF measles antibody titre, type and interval between periodic complexes (EEG discharges). Myoclonus or atonia occurred in all patients and was time-related to the EEG periodic complexes; in 32% of patients, myoclonus or atonia were not clinically evident. The EEG periodic complexes were of 3 types: Type I (16 patients) periodic giant delta waves; Type II (10 patients) periodic giant delta waves intermixed with rapid spikes or fast activity; and Type III (6 patients), long spike-wave discharges interrupted by giant delta waves. Outcome score was associated with symptoms duration (P < 0.01) and EEG periodic complexes (P < 0.05). Symptom duration was inversely related to final outcome (multi-variable analysis). Long VSEEG monitoring greatly improves early diagnosis and detection of subtle atonia or segmental myoclonus. Prognostic factors were the type of EEG periodic complexes and duration of symptoms at presentation.     

EEG asymmetry and heart rate during experience of hypnotic analgesia in high and low hypnotizables

This study evaluates the effects of hypnotic analgesia and hypnosis on bilateral EEG activity recorded from frontal, central and posterior areas during three painful electrical stimulation conditions: waking, hypnosis/no-analgesia, hypnosis/analgesia. Eight high-hypnotizable and eight low-hypnotizable (right handed) subjects participated in the experiment. The following measures were obtained: pain and distress tolerance ratings; EEG spectral amplitudes for the frequency bands: delta (0.5-3.75 Hz), theta 1 (4-5.75 Hz), theta 2 (6-7.75 Hz), alpha 1 (8-9.75 Hz), alpha 2 (10-12.75 Hz), beta 1 (13-15.75 Hz), beta 2 (16-31.75 Hz), total band (0.5-31.75 Hz), '40-Hz' (36-44 Hz); cardiac interbeat interval (ms); mid-frequency and high-frequency peaks from power spectral analysis of heart period variability. During hypnosis/analgesia, high hypnotizable subjects displayed significant reductions in pain and distress scores compared to hypnosis/no-analgesia and waking conditions. In each experimental condition these subjects displayed significant lower total and beta 1 amplitudes compared to low hypnotizables. High hypnotizables, on central and posterior recording sites, during both hypnosis/analgesia and hypnosis/no-analgesia conditions also showed total and delta EEG amplitude reductions in both hemispheres and a theta 1 amplitude reduction in the left hemisphere. However, for total, delta and beta 1 bands in the hypnosis/analgesia condition the amplitude reduction was more pronounced in the right hemisphere as shown by hemispheric asymmetry in favor of the left hemisphere. Low hypnotizables, on posterior recording sites, displayed a delta amplitude reduction during hypnosis/no-analgesia and hypnosis/analgesia conditions. These subjects also showed, for all recording sites, a reduction in theta 1 amplitude during hypnosis/no-analgesia compared to the waking condition. Lows, however, failed in evidencing amplitude differences between hypnosis/no-analgesia and hypnosis/analgesia conditions. During hypnotic analgesia the hemispheric asymmetry found in high hypnotizables was parallel to a significant reduction in the spectral mid-frequency peak of heart period variability which indicated a decrease in the level of sympathetic activity. In contrast, during hypnosis/no-analgesia the EEG amplitude reduction was not paralleled by a decrease in sympathetic activity.     

A hybrid computational model for ultrasound phased-array heating in presence of strongly scattering obstacles

BACKGROUND: Studies using electroencephalogram (EEG) measures of activation asymmetry have reported differences in anterior asymmetry between depressed and nondepressed subjects. Several studies have suggested reciprocal relations between measures of anterior and posterior activation asymmetries. We hypothesized that depressed subjects would fail to show the normal activation of posterior right hemisphere regions in response to an appropriate cognitive challenge. METHODS: EEG activity was recorded from 11 depressed and 19 nondepressed subjects during the performance of psychometrically matched verbal (word finding) and spatial (dot localization) tasks. Band power was extracted from all epochs of artifact-free data and averaged within each condition. Task performance was also assessed. RESULTS: Depressed subjects showed a specific deficit in the performance of the spatial task, whereas no group differences were evident on verbal performance. In posterior scalp regions, nondepressed controls had a pattern of relative left-sided activation during the verbal task and relative right-sided activation during the spatial task. In contrast, depressed subjects failed to show activation in posterior right hemisphere regions during spatial task performance. CONCLUSIONS: These findings suggest that deficits in right posterior functioning underlie the observed impairments in spatial functioning among depressed subjects.     

EEG power spectra of normal preadolescent twins. Gender differences of quantitative EEG maturation

To determine developmental changes of quantitative EEG maturation, we investigated the electroencephalogram (EEG) power spectra in a sample of 72 pairs of healthy twins (144 subjects, 75 girls and 69 boys) ranging in age from 7-15 years. Main spectral parameters were measured in 16 EEG channels. The statistical significance of differences in the EEG power spectra was compared in relation to age and gender. Gender differences were tested by comparing the EEG parameters of boys and girls in the whole sample and separately in the subgroup of dizygotic twins of the opposite sex (DZO twin pairs). A statistically significant decrease of absolute power occurred with increasing age. A significant redistribution of relative power also appeared in higher age, mainly consisting of a progressive increase of alpha 2 power inversely related to relative alpha 1 and theta power. Polynomial regression models of the relation between alpha 2 and theta relative power with age were best described by a 5-order function. The mean frequency of activity across all spectra also increased with age and was maximal in the eldest subjects (13-15 years), with a significantly higher mean frequency of alpha 2 power in females. Similar age and gender differences were less marked in the subgroup of DZO twin pairs. The topographic distribution of spectral bands in normal subjects suggested an earlier maturation of midparietal or occipital than frontocentral regions, and indicated that the growth spurt does not occur simultaneously over homologous right and left hemisphere regions at the same age.     

Frontal brain asymmetry predicts affective style in men.

Recent research suggests that a significant relationship between frontal brain asymmetry (FBA) and affective style can be documented in women with l-measurement occasion. The purpose of this study was to determine whether this finding is generalizable to men. Resting electroencephalogram (EEG)- activity was recorded from male adults during 5 60-s baselines on 1 measurement occasion. Mean alpha power asymmetry was extracted in midfrontal and lateral-frontal sites. For the lateral-frontal site, but not the midfrontal site, there was a significant relationship between relative left anterior activation and positive affective style. These results suggest that lateral FBA is a robust and state-independent measure of affective style in men. (PsycINFO Database Record (c) 2010 APA, all rights reserved)