EEG-based investigation of brain connectivity changes in psychotic patients undergoing the primitive expression form of dance therapy: a methodological pilot study.

Primitive expression (PE) is a form of dance therapy (DT) that involves an interaction of ethologically and socially based forms which are supplied for re-enactment. There exist very few studies of DT applications including in their protocol the measurement of neurophysiological parameters. The present pilot study investigates the use of the correlation coefficient (ρ) and mutual information (MI), and of novel measures extracted from ρ and MI, on electroencephalographic (EEG) data recorded in patients with schizophrenia while they undergo PE DT, in order to expand the set of neurophysiology-based approaches for quantifying possible DT effects, using parameters that might provide insights about any potential brain connectivity changes in these patients during the PE DT process. Indication is provided for an acute potentiation effect, apparent at late-stage PE DT, on the inter-hemispheric connectivity in frontal areas, as well as for attenuation of the inter-hemispheric connectivity of left frontal and right central areas and for potentiation of the intra-hemispheric connectivity of frontal and central areas, bilaterally, in the transition from early to late-stage PE DT. This pilot study indicates that by using EEG connectivity measures based on ρ and MI, the set of useful neurophysiology-based approaches for quantifying possible DT effects is expanded. In the framework of the present study, the causes of the observed connectivity changes cannot be attributed with certainty to PE DT, but indications are provided that these measures may contribute to a detailed assessment of neurophysiological mechanisms possibly being affected by this therapeutic process.

Sleep EEG and spindle characteristics after combination treatment with clozapine in drug-resistant schizophrenia: a pilot study.

PURPOSE: Clozapine is an atypical neuroleptic agent, effective in treating drug-resistant schizophrenia. The aim of this work was to investigate overall sleep architecture and sleep spindle morphology characteristics, before and after combination treatment with clozapine, in patients with drug-resistant schizophrenia who underwent polysomnography. METHODS: Standard polysomnographic techniques were used. To quantify the sleep spindle morphology, a modeling technique was used that quantifies time-varying patterns in both the spindle envelope and the intraspindle frequency. RESULTS: After combination treatment with clozapine, the patients showed clinical improvement. In addition, their overall sleep architecture and, more importantly, parameters that quantify the time-varying sleep spindle morphology were affected. Specifically, the results showed increased stage 2 sleep, reduced slow-wave sleep, increased rapid eye movement sleep, increased total sleep time, decreased wake time after sleep onset, as well as effects on spindle amplitude and intraspindle frequency parameters. However, the above changes in overall sleep architecture were statistically nonsignificant trends. CONCLUSIONS: The findings concerning statistically significant effects on spindle amplitude and intraspindle frequency parameters may imply changes in cortical sleep EEG generation mechanisms, as well as changes in thalamic pacing mechanisms or in thalamo-cortical network dynamics involved in sleep EEG generation, as a result of combination treatment with clozapine. SIGNIFICANCE: Sleep spindle parameters may serve as metrics for the eventual development of effective EEG biomarkers to investigate treatment effects and pathophysiological mechanisms in schizophrenia.

Dynamics of regional brain activity in epilepsy: a cross-disciplinary study on both intracranial and scalp-recorded epileptic seizures.

OBJECTIVE: Recent cross-disciplinary literature suggests a dynamical analogy between earthquakes and epileptic seizures. This study extends the focus of inquiry for the applicability of models for earthquake dynamics to examine both scalp-recorded and intracranial electroencephalogram recordings related to epileptic seizures. APPROACH: First, we provide an updated definition of the electric event in terms of magnitude and we focus on the applicability of (i) a model for earthquake dynamics, rooted in a nonextensive Tsallis framework, (ii) the traditional Gutenberg and Richter law and (iii) an alternative method for the magnitude-frequency relation for earthquakes. Second, we apply spatiotemporal analysis in terms of nonextensive statistical physics and we further examine the behavior of the parameters included in the nonextensive formula for both types of electroencephalogram recordings under study. MAIN RESULTS: We confirm the previously observed power-law distribution, showing that the nonextensive formula can adequately describe the sequences of electric events included in both types of electroencephalogram recordings. We also show the intermittent behavior of the epileptic seizure cycle which is analogous to the earthquake cycles and we provide evidence of self-affinity of the regional electroencephalogram epileptic seizure activity. SIGNIFICANCE: This study may provide a framework for the analysis and interpretation of epileptic brain activity and other biological phenomena with similar underlying dynamical mechanisms.

Amplitude normalization applied to an artificial neural network-based automatic sleep spindle detection system.

Sleep spindles are significant rhythmic transients present in the sleep electroencephalogram (EEG) of non-rapid eye movement (NREM) sleep. Automatic sleep spindle detection techniques are sought for the automation of sleep staging and the detailed study of sleep spindle patterns, of possible physiological significance. A deficiency of many of the available automatic detection techniques is their reliance on the amplitude level of the recorded EEG voltage values. In the present work, an automatic sleep spindle detection system that has been previously proposed, using a Multi-Layer Perceptron (MLP) Artificial Neural Network (ANN), was evaluated using a voltage amplitude normalization procedure, with the aim of making the performance of the ANN independent of the absolute voltage level of the individual subjects' recordings. The application of the normalization procedure led to a reduction in the false positive rate (FPR) as well as in the sensitivity. When the ANN was trained on a combination of data from healthy subjects, the reduction of FPR was from 42.6% to 19%, while the sensitivity of the ANN was kept at acceptable levels, i.e., 73.4% for the normalized procedure vs 84.6% for the non-normalized procedure.

Differences in EEG delta frequency characteristics and patterns in slow-wave sleep between dementia patients and controls: a pilot study.

PURPOSE: To evaluate the modifications of EEG activity during slow-wave sleep in patients with dementia compared with healthy elderly subjects, using spectral analysis and period-amplitude analysis. METHODS: Five patients with dementia and 5 elderly control subjects underwent night polysomnographic recordings. For each of the first three nonrapid eye movement-rapid eye movement sleep cycles, a well-defined slow-wave sleep portion was chosen. The delta frequency band (0.4-3.6 Hz) in these portions was analyzed with both spectral analysis and period-amplitude analysis. RESULTS: Spectral analysis showed an increase in the delta band power in the dementia group, with a decrease across the night observed only in the control group. For the dementia group, period-amplitude analysis showed a decrease in well-defined delta waves of frequency lower than 1.6 Hz and an increase in such waves of frequency higher than 2 Hz, in incidence and amplitude. CONCLUSIONS: Our study showed (1) a loss of the dynamics of delta band power across the night sleep, in dementia, and (2) a different distribution of delta waves during slow-wave sleep in dementia compared with control subjects. This kind of computer-based analysis can highlight the presence of a pathologic delta activity during slow-wave sleep in dementia and may support the hypothesis of a dynamic interaction between sleep alteration and cognitive decline.

Performance evaluation of an Artificial Neural Network automatic spindle detection system.

Sleep spindles are transient waveforms found in the electroencephalogram (EEG) of non-rapid eye movement (NREM) sleep. Sleep spindles are used for the classification of sleep stages and have been studied in the context of various psychiatric and neurological disorders, such as Alzheimer's disease (AD) and the so-called Mild Cognitive Impairment (MCI), which is considered to be a transitional stage between normal aging and dementia. The visual processing of whole-night sleep EEG recordings is tedious. Therefore, various techniques have been proposed for automatically detecting sleep spindles. In the present work an automatic sleep spindle detection system, that has been previously proposed, using a Multi-Layer Perceptron (MLP) Artificial Neural Network (ANN), is evaluated in detecting spindles of both healthy controls, as well as MCI and AD patients. An investigation is carried also concerning the visual detection process, taking into consideration the feedback information provided by the automatic detection system. Results indicate that the sensitivity of the detector was 81.4%, 62.2%, and 83.3% and the false positive rate was 34%, 11.5%, and 33.3%, for the control, MCI, and AD groups, respectively. The visual detection process had a sensitivity rate ranging from 46.5% to 60% and a false positive rate ranging from 4.8% to 19.2%.

Independent component analysis for source localization of EEG sleep spindle components.

Sleep spindles are bursts of sleep electroencephalogram (EEG) quasirhythmic activity within the frequency band of 11-16 Hz, characterized by progressively increasing, then gradually decreasing amplitude. The purpose of the present study was to process sleep spindles with Independent Component Analysis (ICA) in order to investigate the possibility of extracting, through visual analysis of the spindle EEG and visual selection of Independent Components (ICs), spindle "components" (SCs) corresponding to separate EEG activity patterns during a spindle, and to investigate the intracranial current sources underlying these SCs. Current source analysis using Low-Resolution Brain Electromagnetic Tomography (LORETA) was applied to the original and the ICA-reconstructed EEGs. Results indicated that SCs can be extracted by reconstructing the EEG through back-projection of separate groups of ICs, based on a temporal and spectral analysis of ICs. The intracranial current sources related to the SCs were found to be spatially stable during the time evolution of the sleep spindles.

Independent components of sleep spindles.

Sleep spindles are considered a hallmark of stage 2 of the sleep electroencephalogram (EEG) and are used both for sleep staging and for clinical studies of pharmacological agents. Analyses of sleep spindle topography, as well as intracranial source investigations provided evidence for the existence of two distinct sleep spindle types, "slow" and "fast" spindles at approximately 12 and 14 Hz, respectively. The aim of the present study was to apply Independent Component Analysis (ICA) to sleep spindles, for examining the possibility of extracting, through visual analysis of the spindle EEG and selection of Independent Components (ICs), spindle "components" corresponding to separate EEG activity patterns, and to investigate the sources underlying these spindle components. The inverse electromagnetic problem was solved using Low-Resolution Brain Electromagnetic Tomography (LORETA). Results indicate separability and stability of sources related to sleep spindle components reconstructed from separate groups of ICs.

Effect of schizotypy on cognitive performance and its tuning by COMT val158 met genotype variations in a large population of young men.

BACKGROUND: Mirroring schizophrenia, specific dimensions of schizotypy are related to cognitive dysfunction. The relation of schizotypy and state psychopathology to cognitive performance and its link to catechol-O-methyltransferase (COMT) val(158) met genotype variations was studied in a large sample of young men. METHODS: State psychopathology and schizotypy were assessed with self-rated questionnaires. Cognitive performance was assessed with tests of reasoning ability, sustained attention, and verbal and spatial working memory. Subjects were genotyped for the val(158) met polymorphism of the gene for COMT (low enzymatic activity met/met, intermediate met/val, and high val/val). RESULTS: The val/val group had higher scores in measures of state psychopathology as well as negative and disorganized schizotypy dimensions, whereas there was no effect of COMT genotype on cognitive performance measures. Structural equation modeling showed that cognitive performance accuracy but not speed decreased with increasing negative schizotypy, increased with increasing paranoid schizotypy, and was not affected by state psychopathology. Increasing val loading resulted in a dose-dependent increase in the factor loading for the relation between negative schizotypy and cognitive performance accuracy. CONCLUSIONS: Different schizotypal phenotypes had opposing relations to cognitive performance in the population. COMT genotype modulated the relation between the negative schizotypal phenotype and cognitive performance.

Short-term psychological impact on family members of intensive care unit patients.

OBJECTIVE: This study aimed to evaluate the short-term psychological impact on family members of intensive care unit (ICU) patients during their stay in the unit. METHODS: Thirty-two first-degree relatives of patients treated in the ICU of two general hospitals were investigated for symptoms of early posttraumatic stress reaction, anxiety, and depression. Patients' and relatives' sociodemographic data and information pertaining to the patients' ICU treatment were collected. Family members were assessed at intake and before discharge through the Center for Epidemiological Studies Depression Scale, the State-Trait Anxiety Inventory, and the Impact of Event Scale. RESULTS: High rates of anxiety, depressive (97%), and posttraumatic stress (81%) symptoms were recorded at the initial assessment. Although symptoms remitted significantly, 87% and 59% of the sample fulfilled the criteria for a depressive and posttraumatic stress reaction, respectively, at the second assessment. Women exhibited higher levels of distress and more persisting symptoms than men did. Trait anxiety was the most significant predictor (P<.001) of the severity of depressive symptoms and the single predictor of the development of posttraumatic stress reaction (P<.000); also, state anxiety was a predictor of the development of posttraumatic stress symptoms, especially of the female gender. CONCLUSIONS: Family members of ICU patients exhibit high levels of distress that persist throughout their relatives' hospitalization. Women and individuals with high trait anxiety are at increased risk for developing such reactions. Severe early anxiety responses predicted the development of posttraumatic stress symptoms. Early case identification and intervention may prevent the full development of posttraumatic stress disorder.

Melatonin secretion after head injury: a pilot study.

PRIMARY OBJECTIVE: To investigate the circadian rhythm of serum melatonin in patients with traumatic brain injury (TBI) during Intensive Care Unit (ICU) stay and its relationship with core body temperature fluctuations and measures of severity of their condition. METHODS AND PROCEDURES: The pilot study was conducted in the ICU of a general hospital in Athens, Greece. Blood melatonin was determined in eight patients consecutively admitted at the ICU following severe head injury, eight times per day during the first and second day following admission. Core body temperature was recorded at hourly intervals. Patients were also assessed with the Glasgow Coma Score (GCS) and the APACHE II score. RESULTS: Melatonin concentrations were lower than the normally reported values. Mean night-time melatonin levels were higher than mean daytime levels both on the first and second days, although not statistically significant. Diurnal variation of melatonin was associated with the GCS. Thus, patients with low GCS (n = 4) did not exhibit a consistent diurnal variation of melatonin, whereas those with high GCS (n = 4) retained the normally expected fluctuations. CONCLUSIONS: ICU-treated TBI patients exhibit reduced melatonin levels and a circadian secretion profile which is related to the severity of the injury. Patients with more severe head trauma exhibit a clearly disrupted pattern of melatonin secretion, whereas those with less severe trauma preserve a relatively intact diurnal rhythm. Furthermore, the diurnal secretion pattern of melatonin appeared to be dissociated from the circadian rhythm of core body temperature. These preliminary findings may have implications for the management of TBI patients.

The mirror antisaccade task: direction-amplitude interaction and spatial accuracy characteristics.

In this study we examined the performance of human subjects in three oculomotor tasks: a visually guided saccade task (VST), a simple antisaccade task (SAT) and a mirror antisaccade task (MAT). The stimulus presentation was identical for all three tasks, and the differentiation of the tasks was based on the instruction given to the subjects. Subjects were instructed to either look at a visually presented target location (visually triggered saccade task), or to look at the opposite direction of the visually presented target (simple antisaccade task) or finally to look at the mirror location opposite to the location of the visually presented target (mirror antisaccade task). The loading of the simple antisaccade task with the addition of the amplitude requirement did not affect the percentage of directional errors but slowed down the onset of antisaccade execution by 19 ms. The amplitude of the directionally correct antisaccade in the mirror antisaccade task showed a significant distortion of the true mirror target location. This dysmetria followed the same qualitative pattern to that observed for the visually guided saccades, i.e., a near-target hypermetria together with a far-target hypometria, but both these features were exaggerated in the mirror antisaccade task. This distorted amplitude modulation of mirror antisaccade amplitude was completely lost in corrected antisaccades that followed a directional error.