The effects of nicotine plus haloperidol compared to nicotine only and placebo nicotine only in reducing tic severity and frequency in Tourette's disorder.

We studied the effects of chewing nicotine gum on tic frequency and severity in 10 patients with Tourette's disorder (TD) on haloperidol, versus 9 untreated TD patients; placebo gum was administered to 5 of these untreated patients. Videotapes of patients during a 2-hr period of 30 min baseline, 30 min gum chewing, and two 30-min postgum-chewing periods were utilized. For those TD patients on haloperidol, significant reductions occurred in tic frequency and severity during the gum-chewing and the two postgum-chewing periods. Nicotine gum alone caused a decrease in tic frequency only during gum-chewing and one postgum-chewing period, while placebo gum showed no effect. In this study, nicotine markedly potentiated haloperidol effects in treating TD, and showed lesser effects on TD when used alone.     

Long-term stability and consistency of EEG event-related (de-)synchronization across different cognitive tasks.

OBJECTIVE: We examined whether task-related band power changes (event-related desynchronization/synchronization; ERD/ERS) that have been linked to individual differences in cognitive ability demonstrate satisfying temporal stability and cross-situational consistency. METHODS: Multi-channel EEG recordings from 29 adults, assessed at three different occasions over 2 years were examined. Between-session correlations and consistency coefficients (Cronbach's alpha) across the three experiments were evaluated for both, spectral power features of the resting EEG and ERD/ERS estimates while the participants performed some cognitive task (i.e. different elementary cognitive tasks that put comparable demands on the participants). RESULTS: ERD/ERS values, while subjects performed a cognitive task, demonstrated satisfactory stability and consistency (i.e. >0.7), whereby the degree of consistency varied as a function of frequency band and brain region. Highest consistency was found for the 8-10 Hz ERD in parieto-occipital recording sites (i.e. >0.9). In resting EEG, mean alpha (gravity) frequency was the most stable EEG feature. CONCLUSIONS: The present data suggest that ERD/ERS phenomena in different narrow frequency bands are rather stable over time and across different situations. The relatively high reproducibility of ERD/ERS promotes the usefulness of this measure in assessing individual differences of physiological activation patterns accompanying cognitive performance. SIGNIFICANCE: This study addresses the issue of reproducibility of EEG in general and ERD/ERS experiments in particular, which is a prerequisite for both basic research and clinical studies.     

Effect on electroencephalogram of chewing flavored gum

The objective of the present study was to evaluate the effect on the electroencephalogram (EEG) of a chewing gum with and without our prepared new flavor. Electroencephalograms were obtained after the following three tests: chewing pure gumbase with sucrose (standard gumbase), chewing flavored standard gum and the inhalation of flavored aromatic oil. As the control, we used the pre-stimulus control EEG record without a stimulus. We examined the relationship between the pre-stimulus control record and the post-stimulus record using the changes of power in four bands. Chewing the standard gumbase led to an increase in the alpha wave and a decrease in the beta wave. Chewing the flavored standard gum and inhaling the flavored aromatic oil each increased the alpha and beta waves. In addition, chewing the flavored standard gum led to a change in the ratio of theta wave in the frontal area. The difference in the theta, alpha and beta bands in chewing gum with and without the added flavor suggested that the flavor as well as chewing could induce concentration with a harmonious high arousal state in brain function.     

EEG hemispheric asymmetry as a predictor and correlate of short-term response to clozapine treatment in schizophrenia.

In search of early neuroleptic response predictors in schizophrenia, functional interhemispheric and intrahemispheric asymmetry indices, derived from spectrally analyzed resting electroencephalographic (EEG) activity, were examined in 17 schizophrenic patients prior to open label treatment with the atypical neuroleptic clozapine. Compared to EEG asymmetry indices derived from a normative data bank, patients exhibited significant interhemispheric (left greater than right) and intrahemispheric (anterior greater than posterior) deviations in delta, theta, alpha and beta frequency bands. Intrahemispheric indices were positively correlated with clinical ratings of positive symptoms and global psychopathology. Clozapine-induced improvements in positive and negative symptoms and global psychopathology symptom ratings were related to pretreatment intrahemispheric asymmetry only, with relationships varying with symptom, recording region and frequency band. The results are discussed in relation to the neurobiology of schizophrenia and the utility of EEG as an informative predictor of treatment response.     

Quantitative EEG analysis at rest and during photic stimulation in drug-naive patients with first-episode paranoid schizophrenia

In the present study, quantitative EEG analysis was performed at rest and during 10 Hz photic stimulation in 14 drug-naive patients with first-episode paranoid schizophrenia and 20 sex- and age-matched control subjects. Compared with the normal controls, the patients had significantly lower alpha-2 band amplitude in the resting EEG over all recording regions. No significant group differences were found in other frequency bands. In addition, EEG analysis during photic stimulation demonstrated that the patients had a rather uniform topographic profile in EEG amplitude for the alpha band, with significant group differences being confined to the posterior regions in the left hemisphere. There were no significant group differences in the amplitude for the frequency bands harmonically related to the stimulus frequency. These findings provide further evidence that schizophrenic patients have abnormal EEG activity in both non-stimulus and stimulus conditions, and suggest a dysfunction in the mechanisms underlying EEG alpha generation in schizophrenia.     

精神分裂症光驱动反应初步研究

目的　用定量分析法研究精神分裂症脑电图光驱动反应。方法　对 4 5例偏执型精神分裂症患者和正常健康者 5 0例 ,记录安静状态下脑电图 ,并进行闪光刺激。闪光刺激的频率为 5、1 0和 1 5Hz。经自动快速傅立叶转换 (FFT) ,将安静状态和闪光刺激中的脑电图功率值转换成振幅 ,对两组进行比较。结果　闪光刺激中 ,1 0Hz光刺激相对应的α带域 (9 5～ 1 0 5Hz)的振幅显示出独特的曲线 ,精神分裂症缺乏α波枕部优势特征 ,两组间的差异在左侧大脑半球的后颞部及枕部更显著 (P <0 0 5 )。安静状态下 ,精神分裂症患者组在α2 波带的所有部位比正常对照组有显著低的振幅 (P <0 0 5 ) ,而在其他波带的差异无显著意义。结论　精神分裂症有异常的光驱动反应 ,存在α波发生源的功能异常 ,支持本病左半球功能障碍的假说     

EEG from a single-channel dry-sensor recording device

While a laboratory setting and research-grade electroencephalogram (EEG) equipment allow control of variables and high-quality multiple-channel EEG recording, there are situations and populations for which this is not suitable. The present studies examined the validity of a new method of single-channel EEG measurement that is portable and uses dry-sensor technology. In study 1, EEG was recorded simultaneously from the portable device and 4 standard EEG electrodes from a research system, during eyes open (EO) and eyes closed (EC) resting conditions, with 20 adult participants. Average correlations with the research system frequency spectra were highest at site F3 for portable device data processed onboard of the device (r = .90), and for device data processed in a standard manner (r = .89). Further, predictable variations in EO versus EC comparisons were observed. In study 2, twenty-three healthy children had EEGs recorded from the portable device during EO and EC resting conditions, and 3 EO active conditions (ie, relaxation, attention, and cognitive load). Absolute and relative EEG band power differed between conditions in predicted ways, including a reduction in relative theta power and an increase in relative alpha power in EC compared to EO resting conditions. Overall, the results suggest that, while limited in terms of scalp recording locations, the portable device has potential utility in certain EEG recording situations where ease of use is a priority.     

Nicotine potentiation of haloperidol in reducing tic frequency in Tourette's disorder.

In an open, nonblind study, 10 patients with Tourette's disorder who were being treated with haloperidol were videotaped before, while, and after chewing nicotine gum. The frequency of tics was reduced significantly during the 30-minute gum-chewing period and during the 1 hour after gum chewing. Nicotine appears to potentiate haloperidol effects in patients with Tourette's disorder.     

EEG asymmetry in schizophrenic patients before and during neuroleptic treatment

Lateral asymmetry of electroencephalographic (EEG) spectra was assessed in schizophrenic patients compared to normal controls. Ten predominantly unmedicated schizophrenic inpatients and nine normal controls performed monitored cognitive tasks during bilateral recording of EEG from parietal and temporal sites. Lateralization of EEG power in five frequency bands was compared between the groups; separate analyses were performed for linked ears and vertex references. A subsample of schizophrenic patients was restudied after a period of neuroleptic treatment. All significant group differences were obtained with the linked ears reference only. Pretreatment schizophrenics manifested relatively less alpha power over the right hemisphere during all conditions than controls, particularly in the parietal leads. After treatment, there was a significant shift in alpha lateralization toward the control values. These latter effects were also present in the theta frequency band to a lesser extent.     

Quantitative electroencephalography in Alzheimer's disease: comparison with a control group, population norms and mental status

OBJECTIVE: Given that quantitative electroencephalography (EEG) has repeatedly shown excessive slow wave activity in dementia of the Alzheimer type (DAT) that increases with disease progression, we assessed the clinical utility of this tool by comparing various approaches used to assess slowing. DESIGN: Cross-sectional study comparing quantitative EEG data from patients with DAT with normative data from an elderly control group and from EEG norms derived from a large population. PARTICIPANTS: 35 subjects diagnosed with probable DAT and 30 elderly controls. OUTCOME MEASURE: EEG recorded from 21 scalp sites of each patient and elderly control during vigilance-controlled, eyes-closed, resting conditions was spectrally analyzed to yield measures of absolute and relative power in delta, theta, alpha and beta bands and indices of mean alpha band and total band frequency. RESULTS: Group comparisons of raw or age-regressed z-score population normative values yielded different profiles with respect to direction of frequency band changes, regional topography and clinical rating correlations, but both procedures evidenced overall patterns of EEG slowing in DAT. However, both methodologies yielded only modest (75%) classification rates. CONCLUSION: Quantitative EEG remains a valuable research tool but, as yet, an unproven diagnostic tool, for DAT.     

Hippocampal atrophy and EEG markers in subjects with mild cognitive impairment

OBJECTIVE: The present study evaluates the potential relationship between hippocampal atrophy and EEG brain rhythmicity, as assessed by relative band power and alpha frequency indices in a cohort of subjects with mild cognitive impairment (MCI). METHODS: Eighty-eight subjects falling within the definition of MCI patients were enrolled. All subjects underwent EEG recording and magnetic resonance imaging (MRI). Volumetric morphometry estimates of the hippocampal region were computed. Individual EEG frequencies were indexed by the theta/alpha transition frequency (TF) and the individual alpha frequency (IAF). The relative power was separately computed for delta, theta, alpha1, alpha2 and alpha3 frequency bands. The MCI cohort was classified into four subgroups, based on the mean and standard deviations of the hippocampal volume of a normal elderly control sample. RESULTS: The group with moderate hippocampal atrophy showed the highest increase in the theta power on frontal regions, and of the alpha2 and alpha3 powers on frontal and temporo-parietal areas. The analysis of the individual alpha frequency markers showed that the values for the alpha markers were highest in the group with the smallest hippocampal volume, whereas in the group with moderate hippocampal atrophy, these values were lower than in the group with severe atrophy. CONCLUSIONS: The relationship between hippocampal atrophy and EEG activity changes in MCI subjects is not proportional to the hippocampal atrophy. Therefore, EEG markers could represent a new tool for differential diagnosis. SIGNIFICANCE: The hippocampal atrophy induces different brain synchronization/desynchronization patterns. EEG changes model the brain activity induced by a discrete change of the hippocampal volume. The changes in the EEG rhythmicity differ greatly from those in MCI patients with subcortical vascular damage.     

EEG power changes are related to regional cerebral glucose metabolism in vascular dementia.

OBJECTIVE: In patients with vascular dementia (VD), the relationship between the EEG power within the 4 frequency bands and the regional metabolic disturbances was investigated. METHODS: Twenty-eight patients (age 69.0+/-6.54 years) with VD according to NINDS-AIREN criteria underwent quantitative EEG recording, according to the 10-20 system, and fluodeoxyglucose F18 positron emission tomography (PET) at resting condition within 24 h. EEG power FFT-analysis was performed for delta (2-3.5 Hz), theta (4-7.5 Hz), alpha (8-13 Hz) and beta (13.5-20 Hz) frequency bands. Regional EEG power bands were related to regional glucose metabolism in anatomically defined regions corresponding to locations of the 10-20 system. RESULTS: Correlation between slow frequency band power and glucose metabolism was found. A widespread inverse relationship of delta power to metabolism was found between various regions; additionally, delta power was negatively correlated to cerebral glucose metabolism in individual regions. Frontal theta power correlated especially with thalamic CMRglc. Alpha power correlated directly with metabolism in the occipital lobe. No significant relationships were found between beta power and metabolism. CONCLUSION: We conclude that EEG power in VD is linked to glucose metabolism, indicating specific regional dependencies.     

The brain in fractal time: 1/f-like power spectrum scaling of the human electroencephalogram.

"1/f-like" power spectrum scaling is a ubiquitous feature of complex systems. In such scaling, the power spectrum of a given time series is dominated by an inverse power law, resulting in an inverse linear relation between log power and log frequency. The 1/f-like power spectrum scaling properties of human, resting eyes-closed and eyes-open EEG were examined. For both eyes-closed and eyes-open EEG, log power had a significant inverse linear relation with log frequency. The slope of this relation was not correlated with previously-calculated Grassberger-Procaccia dimension estimates for the same data, indicating that the EEG is not a 1/f-like stochastic process. Further, the degree of deviation from perfect log power versus log frequency linearity was related to power in the 8-12 Hz alpha frequency band. It is speculated that this deviation may be related to the low dimension of a chaotic alpha rhythm relative to other EEG rhythms.     

Insights on the neural basis of motor plasticity induced by theta burst stimulation from TMS–EEG

Transcranial magnetic stimulation (TMS) is a useful tool to induce and measure plasticity in the human brain. However, the cortical effects are generally indirectly evaluated with motor‐evoked potentials (MEPs) reflective of modulation of cortico‐spinal excitability. In this study, we aim to provide direct measures of cortical plasticity by combining TMS with electroencephalography (EEG). Continuous theta‐burst stimulation (cTBS) was applied over the primary motor cortex (M1) of young healthy adults, and we measured modulation of (i) MEPs, (ii) TMS‐induced EEG evoked potentials (TEPs), (iii) TMS‐induced EEG synchronization and (iv) eyes‐closed resting EEG. Our results show the expected cTBS‐induced decrease in MEP size, which we found to be paralleled by a modulation of a combination of TEPs. Furthermore, we found that cTBS increased the power in the theta band of eyes‐closed resting EEG, whereas it decreased single‐pulse TMS‐induced power in the theta and alpha bands. In addition, cTBS decreased the power in the beta band of eyes‐closed resting EEG, whereas it increased single‐pulse TMS‐induced power in the beta band. We suggest that cTBS acts by modulating the phase alignment between already active oscillators; it synchronizes low‐frequency (theta and/or alpha) oscillators and desynchronizes high‐frequency (beta) oscillators. These results provide novel insight into the cortical effects of cTBS and could be useful for exploring cTBS‐induced plasticity outside of the motor cortex.     

Quantitative EEG and dynamic susceptibility contrast MRI in Alzheimer's disease: a correlative study.

OBJECTIVE: To investigate the relationship between the electroencephalographic (EEG) power spectra features obtained by quantitative EEG (qEEG) and the hemodynamic parameters detected by dynamic susceptibility contrast-enhanced MR imaging (DSC MRI) in patients with Alzheimer's disease (AD). METHODS: Fourteen patients with probable AD and 15 elderly healthy controls were included in the study. All subjects underwent both EEG recording in a rest condition and perfusion MRI. Three EEG scalp areas were defined (anterior, central and posterior) and power spectra values were obtained from each scalp area. Relative values of temporoparietal and sensorimotor regional cerebral blood volume (rCBV) were measured bilaterally and successively averaged to obtain a total perfusion index. The brain atrophy index was calculated and used as a covariate to rCBV. Correlation analysis was performed between EEG variables and hemodynamic-morphological parameters. RESULTS: qEEG power spectra of AD patients were characterized by an increase in mean relative power of theta (4-7.75 Hz) associated with a decrease in alpha (8-12.75 Hz) frequency bands with a topographic distribution over the central and posterior EEG scalp regions, when compared with controls; beta (13-31 Hz) frequency band also displayed a significant decrease over the anterior and posterior EEG scalp regions of AD patients with respect to controls. The DSC MRI revealed a bilateral reduction in the temporoparietal and sensorimotor rCBV with respect to controls. Correlation analysis showed that the total level of hypoperfusion selectively correlates with the EEG power spectra in theta and alpha frequency bands distributed over anterior/central and central region, respectively. Within AD patients, the lower the level of hypoperfusion, the higher the content of EEG power spectra in theta frequency band, and the lower the level of hypoperfusion, the lower the content of EEG power spectra in alpha band. CONCLUSIONS: The combined qEEG and DSC MRI technology unveiled a selective correlation between neurophysiological and hemodynamical patterns in AD patients. Further investigations will ascertain the relevance of this multi-modal approach in the heterogeneous clinical context of AD.     

Electroencephalographic vigilance dynamics in multiple sclerosis during an acute episode and after remission

Summary Twenty-three patients with multiple sclerosis were studied during an acute episode and again 4 weeks later. Whereas the patients' clinical condition improved significantly (Kurtzke DSS: from 3.9 (SD 1.4) to 3.3 (SD 1.5),P < 0.001), the conventional power spectra of the resting EEG showed no marked changes. Following a 10-min EEG recording under resting conditions the patients performed a visuomotor tracking task, during which a further EEG recording was made. The frequency of the subvigilant non-A epochs of Loomis et al. as calculated for each minute of the resting recording was taken as the basis for evaluating the EEG dynamics of vigilance. A comparison during and after relapse showed differences in the time courses of the numbers of non-A epochs. While the non-A epochs were not time dependent in the acute phase, remission was characterized by a steady increase in non-A epochs across the 10 min of the recording period. This change in the dynamics of vigilance, which approximates a physiological pattern, was accompanied by an improvement in visuomotor tracking performance. Comparison of the power spectra of the EEG recorded during the tracking task showed a bifrontal increase in absolute alpha power during remission.     

Quantitative EEG analysis in post-traumatic anosmia

Many objective and quantitative methods have been developed to create a procedure or a device to prove, describe and quantify olfactory deficit and anosmia, especially after a head trauma. Electrophysiological testing throughout olfactoelectroencephalography (olfactoEEG) is based on brain activity desynchronisation, and on the subsequent disappearance of alpha activity on the posterior regions after an olfactory stimulus. Yet traditional evaluation of EEG can be difficult, because of little or hardly detectable alpha activity on the posterior regions ('alpha rare'). The aim of this study was to evaluate the Olfactory Stop Reaction (OSR) by means of frequency band power calculation and subsequent topographical mapping in patients with post-traumatic anosmia, who presented 'alpha rare' EEG. Twenty-five consecutive patients, affected by anosmia caused by head trauma, were submitted to an EEG recording with olfactory stimulation. After signal processing and analysis, an Olfactory Stop Reaction was detected in 17 out of 25 patients; moreover, in these patients we detected a significant decrease in alpha band power in the occipital regions and an increase in theta band power on midline frontal and central regions after olfactory stimulation. In the remaining eight patients, no significant variation in band power was observed. In conclusion, an objective evaluation of the olfactory function with this method of automatic EEG signal analysis allows the limits given by psychophysical methods and traditional EEG to be overcome and attempts to fulfil the requirements for standardization of olfactory function evalution.     

EEG findings in heroin addicts during induction and maintenance on methadone.

This study investigated changes in the EEG of addicts initially on heroin as they progressed through the induction and maintenance phases of a methadone program. Spectral analysis of bipolar recordings revealed significant consistent differences only in the eyes-closed resting state. Patients under the influence of heroin showed large sharp peaks at 9-10 c/sec, particularly in the parieto-occipital recording. Methadone induction led either to marked reduction of this peak and widening of alpha band activity or to an increase in frequency of the alpha peak to 12 c/sec. After several months of methadone the alpha peak was still absent unless heroin abuse was present, a theta peak was present in three of four patients, and the alpha bandwidth remained broad. Changes in the theta band were more difficult to interpret.     

Computerized EEG frequency analysis: sensitivity and specificity in patients with focal lesions

We performed computerized EEG frequency analysis (C-EEGFA) in 69 controls and 20 patients with focal brain lesions and focally abnormal conventional EEGs. Individual channel EEG frequency analysis variables that were helpful in differentiating the 2 groups were absolute delta and theta band power, relative delta, theta, and alpha band powers, and median-power frequency. High-frequency beta band power (20 to 32 Hz) was not useful. Changes in EEG with age were seen only after age 50 and generally consisted of an increase in anterior alpha power, with no significant increase in slowing. Correlations of C-EEGFA variables with posterior alpha power were more significant than correlations with age. Calculating normative C-EEGFA data for 5 subsets of controls, each with a different amount of posterior alpha power, increased the sensitivity of the EEG frequency analysis test without altering the specificity. Even with this correction 2 of 20 patients with focal lesions and focally abnormal conventional EEGs had normal C-EEGFA studies. If these obvious focal lesions produced normal results, more subtle diseases might not be detected. A significant clinical utility of C-EEGFA remains to be proven.     

EEG mapping in patients with social phobia

Recent studies have suggested an information-processing bias in social phobia (SP). Little is known about the electrophysiological correlates of anxiety in SP. The aim of the present study was to investigate the quantitative electroencephalogram (EEG) in 25 drug-free patients with SP as compared with age- and sex-matched normal controls and to correlate anxiety and depressive symptoms with EEG data. EEG was recorded under vigilance-controlled and resting conditions. The Spielberger State and Trait Anxiety Scale (STAI) and the Beck Depression Inventory (BDI) were administered to assess anxiety and depression levels. Multivariate analysis of variance revealed significant differences between patients and controls, specifically frontopolarly and right centrally. Statistical analysis demonstrated a decrease in absolute and relative delta, theta power, alpha-adjacent slow-beta and fast beta power and an increase in absolute and relative intermediate beta power, as well as an acceleration of the total centroid and a slowing in beta centroid and its variability. Trait anxiety and depression scores correlated positively with the dominant alpha frequency and the alpha centroid, and negatively with absolute theta and slow alpha power as well as with the centroid of the delta/theta frequency band. In conclusion, EEG mapping in patients with SP revealed significant differences from normal controls suggesting a hyperarousal as a pathogenetic factor of anxiety.