EEG states of the brain, information processing, and schizophrenic primary symptoms

Schizophrenia and the efficacy of qEEG-guided neurofeedback treatment: a clinical case series

Schizophrenia is sometimes considered one of the most devastating of mental illnesses because its onset is early in a patient's life and its symptoms can be destructive to the patient, the family, and friends. Schizophrenia affects 1 in 100 people at some point during their lives, and while there is no cure, it is treatable with antipsychotic medications. According to the Clinical Antipsychotic Trials for Interventions Effectiveness (CATIE), about 74% of the patients who have discontinued the first medication prescribed within a year will have a relapse afterward. This shows an enormous need for developing better treatment methods and better ways to manage the disease, since current therapies do not have sufficient impact on negative symptoms, cognitive dysfunction, and compliance to treatment. In this clinical case series, we investigate the efficacy of quantitative electroencephalography (qEEG)-guided neurofeedback (NF) treatment in this population, and whether this method has an effect on concurrent medical treatment and on the patients. Fifty-one participants (25 males and 26 females) ranging from 17 to 54 years of age (mean: 28.82 years and SD: 7.94 years) were included. Signed consent was received from all patients. Most of the participants were previously diagnosed with chronic schizophrenia, and their symptoms did not improve with medication. All 51 patients were evaluated using qEEG, which was recorded at baseline and following treatment. Before recording the qEEG, participants were washed out for up to 7 half-lives of the medication. After Food and Drug Administration (FDA)-approved Nx-Link Neurometric analysis, qEEGs suggested a diagnosis of chronic schizophrenia for all participants. This was consistent with the clinical judgment of the authors. The participants' symptoms were assessed by means of the Positive and Negative Syndrome Scale (PANSS). Besides the PANSS, 33 out of 51 participants were also evaluated by the Minnesota Multiphasic Personality Inventory (MMPI) and the Test of Variables of Attention (TOVA), both at baseline and following treatment. Each participant was prescribed an NF treatment protocol based on the results of their qEEG neurometric analysis. Each session was 60 minutes in duration, with 1 to 2 sessions per day. When 2 sessions were administered during a single day, a 30-minute rest was given between the sessions. Changes in the PANSS, MMPI, and TOVA were analyzed to evaluate the effectiveness of NF treatment. The mean number of sessions completed by the participants was 58.5 sessions within 24 to 91 days. Three dropped out of treatment between 30 and 40 sessions of NF, and one did not show any response. Of the remaining 48 participants 47 showed clinical improvement after NF treatment, based on changes in their PANSS scores. The participants who were able to take the MMPI and the TOVA showed significant improvements in these measures as well. Forty were followed up for more than 22 months, 2 for 1 year, 1 for 9 months, and 3 for between 1 and 3 months after completion of NF. Overall NF was shown to be effective. This study provides the first evidence for positive effects of NF in schizophrenia.

Patterns of spontaneous magnetoencephalographic activity in patients with schizophrenia

Magnetoencephalography noninvasively measures the magnetic fields produced by the brain. Pertinent research articles from 1993 to 2009 that measured spontaneous, whole-head magnetoencephalography activity in patients with schizophrenia were reviewed. Data on localization of oscillatory activity and correlation of these findings with psychotic symptoms are summarized. Although the variety of measures used by different research groups makes a quantitative meta-analysis difficult, it appears that magnetoencephalography activity in patients may exhibit identifiable patterns, defined by topographic organization and frequency band. Specifically, 11 of the 12 studies showed increased theta (4-8 Hz) and delta (1-4 Hz) band oscillations in the temporal lobes of patients; of the 10 studies that examined the relationship between oscillatory activity and symptomatology, 8 found a positive correlation between temporal lobe theta activity and positive schizophrenic symptoms. Abnormally high frontal delta activity was not seen. These findings are analyzed in comparison with the electroencephalogram literature on schizophrenics, and possible confounds (e.g., medication effects) are discussed. In the future, magnetoencephalography might be used to assist in diagnosis or might be fruitfully used in conjunction with new neuroscience research approaches such as computational modeling, which may be able to link oscillatory activity and cellular-level pathology.

An EEG approach to the neurodevelopmental hypothesis of schizophrenia studying schizophrenics, normal controls and adolescents

Based on an integrative brain model which focuses on memory-driven and EEG state-dependent information processing for the organisation of behaviour, we used the developmental changes of the awake EEG to further investigate the hypothesis that neurodevelopmental abnormalities (deviations in organisation and reorganisation of cortico-cortical connectivity during development) are involved in the pathogenesis of schizophrenia. First-episode, neuroleptic-naive schizophrenics and their matched controls and three age groups of normal adolescents were studied (total: 70 subjects). 19-channel EEG delta-theta, alpha and beta spectral band centroid frequencies during resting (baseline) and after verbal stimuli were used as measure of the level of attained complexity and momentary excitability of the neuronal network (working memory). Schizophrenics compared with all control groups showed lower delta-theta activity centroids and higher alpha and beta activity centroids. Reactivity centroids (centroid after stimulus minus centroid during resting) were used as measure of update of working memory. Schizophrenics showed partial similarities in delta-theta and beta reactivity centroids with the 11-year olds and in alpha reactivity centroids with the 13-year olds. Within the framework of our model, the results suggest multifactorially elicited imbalances in the level of excitability of neuronal networks in schizophrenia, resulting in network activation at dissociated complexity levels, partially regressed and partially prematurely developed. It is hypothesised that activation of age- and/or state-inadequate representations for coping with realities becomes manifest as productive schizophrenic symptoms. Thus, the results support some aspects of the neurodevelopmental hypothesis.

Differences in the EEG profiles of early and late responders to antipsychotic treatment in first-episode, drug-naive psychotic patients

The aim of this study was to search for differences in the EEG of first-episode, drug-naive patients having a schizophrenic syndrome which presented different time courses in response to antipsychotic treatment. Thirteen patients who fulfilled DSM-IV diagnosis for schizophrenia or schizophreniform disorder participated in this study. Before beginning antipsychotic treatment, the EEG was recorded. On the same day psychopathological ratings were assessed using the ADMDP system, and again after 7 and 28 days of treatment. The resting EEG (19 leads) was subject to spectral analysis involving power values for six frequency bands. The score for the schizophrenic syndrome was used to divide the patients into two groups: those who displayed a clinically meaningful improvement of this syndrome (reduction of more than 30%) after 7 days of treatment (early responders, ER) and those who showed this improvement after 28 days (late responders. LR). Analysis of variance for repeated measures between ER, LR and their matched controls with the 19 EEG leads yielded highly significant differences for the factor group in the alpha2 and beta2 frequency band. No difference was found between the slow-wave frequency bands. Compared to controls the LR group showed significantly higher alpha2 and beta2 power and, in comparison to the ER group, significantly higher alpha2 power. There were no significant differences between the ER and the control group. These findings point to differences in brain physiology between ER and LR. The implications for diagnosis and treatment are discussed.

Frequency domain source localization shows state-dependent diazepam effects in 47-channel EEG

The topic of this study was to evaluate state-dependent effects of diazepam on the frequency characteristics of 47-channel spontaneous EEG maps. A novel method, the FFT-Dipole-Approximation (Lehmann and Michel, 1990), was used to study effects on the strength and the topography of the maps in the different frequency bands. Map topography was characterized by the 3-dimensional location of the equivalent dipole source and map strength was defined as the spatial standard deviation (the Global Field Power) of the maps of each frequency point. The Global Field Power can be considered as a measure of the amount of energy produced by the system, while the source location gives an estimate of the center of gravity of all sources in the brain that were active at a certain frequency. State-dependency was studied by evaluating the drug effects before and after a continuous performance task of 25 min duration. Clear interactions between drug (diazepam vs. placebo) and time after drug intake (before and after the task) were found, especially in the inferior-superior location of the dipole sources. It supports the hypothesis that diazepam, like other drugs, has different effects on brain functions depending on the momentary functional state of the brain. In addition to the drug effects, clearly different source locations and Global Field Power were found for the different frequency bands, replicating earlier reports (Michel et al., 1992).

EEG reactivity and EEG activity in never-treated acute schizophrenics, measured with spectral parameters and dimensional complexity

Our approaches to the use of EEG studies for the understanding of the pathogenesis of schizophrenic symptoms are presented. The basic assumptions of a heuristic and multifactorial model of the psychobiological brain mechanisms underlying the organization of normal behavior is described and used in order to formulate and test hypotheses about the pathogenesis of schizophrenic behavior using EEG measures. Results from our studies on EEG activity and EEG reactivity (= EEG components of a memory-driven, adaptive, non-unitary orienting response) as analyzed with spectral parameters and "chaotic" dimensionality (correlation dimension) are summarized. Both analysis procedures showed a deviant brain functional organization in never-treated first-episode schizophrenia which, within the framework of the model, suggests as common denominator for the pathogenesis of the symptoms a deviation of working memory, the nature of which is functional and not structural.

Electrical brain activity in schizophrenia described by equivalent dipoles of FFT-data

Since results of conventional FFT-power-analysis are reference-dependent, only unambiguous neurophysiological data should be used for a functional physiological interpretation of EEG-data. FFT-approximation with successive center-of-gravity-dipole calculation gives unambiguous EEG-data with regard to recording reference. In the present investigation 22 medicated schizophrenic patients were compared with 22 healthy age- and sex-matched controls with regard to spontaneous resting EEG. More anterior and superficial equivalent-dipoles were found in the beta-bands for schizophrenic patients compared to healthy control subjects. There was a tendency of increased beta-activity in schizophrenic subjects. With more severe schizophrenic symptoms (higher BPRS-score), the more anterior was the equivalent-dipole localization in the beta 1-band, and the deeper in the theta-band. The different locations of the beta-band dipoles in schizophrenic patients suggest that different neuronal populations generate beta-activity in schizophrenia compared to healthy controls. FFT-approximation allows a substantial and meaningful data reduction in multichannel recordings and will hopefully help in understanding pathological brain functions in schizophrenia.

Event-related potential maps depend on prestimulus brain electric microstate map

The brain functional microstate immediately before each of about 3000 identical tone stimuli was classified using extracted reference-free descriptors (locations of maximal and minimal potential) of the landscape of the brain's momentary electric field, in 8 volunteers. Six prestimulus microstate map classes occurred more than 30 times in each subject, and were clustered into two map class types (totals of 242 and 283 cases, respectively, on the average per subject). Event-related potential (ERP) map series were averaged for each subject and prestimulus map class. Map descriptors were extracted from the ERP maps at times of maximal Global Field Power during the component time windows N100, P200 and P330. Discriminant functions were estimated; for the maps of N100 and P330, the discriminant scores differed significantly between the maps associated with the two prestimulus map class types (paired t-tests, df = 7, p = .014 and p = .005, respectively). The dominant axis of the poststimulus class type II ERP maps deviated clockwise from that of the type I ERP maps in all components. We conclude that subtle changes in the brain's spontaneous momentary functional microstate (as classified by spatial descriptors of a single map) influence event-related information processing by the brain, following common rules over subjects.

Dimensional complexity of EEG brain mechanisms in untreated schizophrenia

The dimensional complexity of left temporal-parietal and parietal-occipital electroencephalographic (EEG) recordings was assessed by computing the correlation dimension during 20 sec in six recording conditions from 15 first-episode acute schizophrenics before medication, 12 other medication-free individuals clinically and socially remitted after a first schizophrenic episode, 17 medication-free neurotics and 17 controls. The correlation dimension of the temporal-parietal EEG differed between groups [analysis of variance (ANOVA)] (p < 0.004), whereas neurotics (different from schizophrenics at p < 0.002) and remitted schizophrenics showed intermediate values. There was no overall significant difference between groups in the parietal-occipital EEG. Differences of the correlation dimension of the temporal-parietal versus the parietal-occipital EEG were significant between groups (ANOVA p < 0.05); first-episode schizophrenics differed from controls (p < 0.002) and remitted patients (p < 0.08). Increased dimensional complexity of schizophrenic EEG was found in one of two examined brain regions. The higher dimensional complexity of functional brain mechanisms in schizophrenics versus normals is reminiscent of the loosened organization of thought, and of suggestions of certain superior abilities in the patients.

EEG reactivity in high and low symptomatic schizophrenics, using source modelling in the frequency domain

A dipole localization method in the frequency domain was used (FFT Dipole Approximation) to assess spatial differences in the spectral EEG reactivity (orienting response) between high and low symptomatic schizophrenics. Frequency bands of interest were determined empirically by comparing the two dichotomized patient groups with two matched control groups. Evidence for a correlation between EEG reactivity and severity of schizophrenic symptomatology was found, especially in the higher beta frequency range (16-25.5 Hz). Opposite effects were found in the two beta ranges of 20.5-22.5 Hz and 23.0-25.5 Hz, supporting the hypothesis that different EEG frequency bands have specific functional significances and that these bands are not necessarily those that are conventionally selected.

EEG coherence during hemispheric activation in schizophrenics

We studied the change of EEG alpha-band coherence between resting and motor performance ("reactivity of EEG coherence") in 18 chronic schizophrenics and 30 normal controls, examining differences between left and right hemisphere tasks. Three coherences were examined for each hemisphere. The central-parietal coherence in normals increased on the left for left hemisphere tasks, and decreased on the right for right hemisphere tasks, whereas the patients showed a decrease of both measures, more on the left side. Thus, the interhemispheric difference of central-parietal coherence reactivity was reversed for the schizophrenics (P less than 0.06) and suggested a left-sided deviation. The lateral-percentral and precentral-central coherences showed no left-right deviations of reactivity in the patients. Since coherence increase is considered to be a sign of the coupled function between the studied regions, our findings suggest a defective coordination of left central-parietal regions during a task in schizophrenics.

A psychobiological model of the pathogenesis of schizophrenic symptoms

Schizophrenic symptoms are non-specific and are modifiable by unspecific drugs, by environmental input and 'spontaneously'. An information-theory-based model of their pathogenesis is presented. The model is based on data and theories which suggest memory-driven and state-dependent brain operations for the organization of human behavior in normal or in psychopathological states. The data are integrated in the concept of EEG-defined functional states of the brain with state-dependent information processing. The brain's functional state is multifactorially defined, reflects at each moment the memory storages accessible to the operations of information processing and is continuously readjusted to the demands made on the organism by current received information as estimated by the cerebral mechanisms of initiation of the orienting reaction and of its 'habituation'. Major conclusions of evoked potentials and of EEG-reactivity studies on information processing anomalies in schizophrenia integrated into the model suggest the following: schizophrenic symptoms reflect the behavioral manifestations of brain's information processes which have access to memory storages which contain mnemonic representations of skills and of cognitive-emotional coping strategies which are inadequate to recognize the age- and state-corresponding significance of the current information for the organism.

Multivariate EEG power spectral analysis in acute schizophrenics

The electroencephalogram (EEG) during information processing is influenced by specific changes in brain electrical activity. Based on the theory of disturbed information processing in schizophrenics, we analysed auditory stimulus induced EEG changes by Fast Fourier Transformation. The most important of the significant stimulation-dependent EEG power changes were measured in the 0.5-3.5 Hz and 10-13.5 Hz frequency bands in the left frontoparietal lead. In a multivariate analysis the separation of the subjects examined into acute schizophrenics and normals was incorrect in only 21% of the cases (resubstitution rate); using pi-method an error of 31% was estimated.

Repeated acoustic stimulation of acute schizophrenic patients and the habituation of EEG power changes

Habituation in psychiatric patients to repeated stimuli has typically been described in connection with the measurement of the skin conductance orienting response. Here EEG power spectra of acute schizophrenic patients and normals to 4 trials of an acoustic stimulation were examined for evidence of habituation. In response to stimulation the alpha EEG reactivity was less distinct in schizophrenics than in normals. This is in agreement with the theory of hypovariability or hyperstability of the EEG in schizophrenics. Signs of habituation in acute schizophrenics were clearer in fast beta frequencies of the parietal leads.

Alpha reactivity in schizophrenia and in schizophrenic spectrum disorders: demographic, clinical and hemispheric assessment

Alpha EEG reactivity was assessed in a carefully diagnosed sample of 84 schizophrenic and schizophrenic spectrum disorder patients, both under resting conditions (eyes closed and eyes open) and during two spatial-geometric cognitive tasks. The influence of the subject's demographic (sex and age), clinical (diagnostic subtypes, disease course, CT scan characteristics) and neurophysiological (hemispheric recording and different cognitive tasks) characteristics on alpha peak reactivity was analyzed by means of multivariate analysis of variance. The results indicated a significant effect of type of illness on alpha EEG reactivity, patients with a diagnosis of undifferentiated and disorganized schizophrenia having the lowest alpha reactivity levels. None of the other variables considered had any contributing effect. The results are discussed in terms of orienting responses and hemispheric CNS organization in functional psychoses.

Spectral EEG correlates of dream recall

Recent studies have shown that dreaming is not limited to rapid eye movement (REM) sleep, but can be found to varying degrees in any stage of sleep. This study attempted to quantify the EEG correlations of dreaming during Stage 2 sleep. Six normal volunteers were studied for 24 nights in the sleep laboratory. Electroencephalogram (EEG) recording prior to awakening from Stage 2 sleep and from other stages without awakening were subjected to computer spectral analysis. Although awakenings associated with dream recall tended to have lower total power, mean frequency in the beta band proved to be the best correlate of mental activity in Stage 2 sleep. Mean frequency had its highest values in REM sleep and wakefulness and declined in Stage 2 and Stage 4 sleep, in keeping with the decline in mental activity reported from these stages. Implications of these findings are discussed with regard to models of dream recall and clinical states.

EEG assessment of brain activity: Spatial aspects, segmentation and imaging

High temporal resolution and sensitivity to index different functional brain states makes the EEG a powerful tool in psychophysiology. Its full potential can now be utilized since recording technology and computational power for the large data masses has become affordable. However, basic traditional strategies in EEG need reviewing. Conventional, spontaneous or evoked EEG traces which are used for various complex analyses give ambiguous information on EEG power (amplitude) and phase for a given point on the scalp. Principally, analysis should first be done over space, then over time, to avoid ambiguities or pre-selections. First or second spatial derivative computations can provide "reference-free" data for analyses over time. We propose to use direct, spatial approaches for the analysis of the scalp EEG field distributions when simultaneous recordings in several EEG channels can be examined. The ambiguity of the conventional EEG waveshapes results in different, equally "correct" scalp maps of EEG power of the same multichannel data for different reference electrodes. An exception are scalp maps of EEG power computed against the common, average reference, as they are related to the reference-free spatial distribution (maps) of the maximal and minimal (extreme) field values over time, and thus are directly interpretable in terms of net orientation of the generator process. A proposed, reference-free EEG segmentation into epochs of periodically stationary spatial distributions of the mapped scalp EEG fields uses the locations of maximal and minimal (extreme) field values at each moment in time as classifiers, and thus avoids the priviledging of two arbitrarily chosen recording points in the field.