Electrodermal Activity and Stress Assessment.

Stress, as a kind of emotion, is inevitable in everyday life. In psychosomatic medicine stress represents a powerful link in the pathophysiological chain of disorder. Having evidence about the power of stress on the body, the interest in medicine was how to measure it in appropriate, fast way and with minimal cost. Electrodermal activity seems to be available for this purpose. The galvanic skin response (GSR) is an objective, transient indication of autonomic nervous system arousal in response to a stimulus. It refers to changes in sweat gland activity that are reflective of the intensity of our emotional arousal. In this article we discuss physiological specifics of skin conductance/resistance and how it is measured in practice. The most used application of GSR is in biofeedback methodology. Biofeedback assessment and training exactly uses skin reaction to different stimuli and aims to gain voluntary control over this autonomic response. The aim of this article is to show effectiveness of this method in paediatric practice.

Neurofeedback - A Method Which Trains the Brain to Obtain Changes in Behaviour.

EEG can determine changes in brain activity that might be useful in diagnosing different brain disorders as well as some mental states. Many advantages of this record have been the reason for resurrect the EEG in current clinical practice and research. More sophisticated form, the Q-EEG comprises a procedure that processes the recorded EEG activity from a multi-electrode recording using a computer, where data is processed with various algorithms, such as the Fourier or Wavelet analysis. Q-EEG data are important as a marker for many psychophysiological disorders. Neurofeedback (NF) is a form of behavioural training aimed at developing skills for self-regulation of brain activity. It is a treatment method for altering brain functioning by the use of signals provided to a patient that reflect the moment-to-moment changes in the patient's electroencephalogram. This article summarizes some of our large experience with neurofeedback training in different groups of disorders in children and adolescents. Positive outcome is promising for more expansive use of this non-pharmacological, cost-benefit methodology in paediatric and general population.

Inter- and Intra-Hemispheric EEG Coherence Study in Adults with Neuropsychiatric Disorders.

Functional connectivity between different regions of the brain in the resting state has been a recent topic of interest in neurophysiological research. EEG coherence happened to be an useful tool for measuring changes in neuro-psycho-physiological functioning which are not detectable by simply measuring amplitude or power spectra. The aim of our study was to investigate the changes in the EEG coherence in groups of different mental disorders such as: depression, general anxiety disorder, ADHD, Asperger syndrome and headaches, compared to control group. All measures were made in two conditions: eye opened (EO) and eyes closed (EC). The obtained results show that in EO condition there is a significantly lower coherence for delta waves between analyzed groups. For theta coherence only for Asperger syndrome we found lower coherence compared to control group, ADHD and headaches in parietal region (P3-P4). Obtained results for intrahemispheric coherence have shown that there was significantly lower coherence in both conditions for delta and theta bands in almost all sites for Asperger's syndrome, and opposite increased intrahemispheric coherence for patients with headaches (for delta band in the anterior regions and for theta band in the posterior regions). ADHD patients expressed lower delta inter-hemispheric coherence in frontal regions, and increased coherence of theta in central regions but increased delta coherence in posterior regions only in EO condition. For depressive and anxiety patients we found decreased intrahemispheric coherence for EO condition for delta brain waves all over the cortex. Concerning the coherence in anxiety patients in our current study we have obtained hypo coherence in centro-parieto-occipital region only for delta in inter-hemispheric coherence and also lower delta coherence through the cortex for intrahemispheric coherence. Our findings for interhemispheric hyper coherence in subjects with depression specifically for alpha and beta bands were confirmed in other studies. We suggest that EEG coherence analysis could be a sensitive parameter in the detection of electrophysiological abnormalities in patients with anxiety, depression, ADHD, Asperger syndrome and headaches. These results can confirm the development of QEEG state and trait biomarkers for psychiatric disorders.

Analysis of independent components of cognitive event related potentials in a group of ADHD adults.

In the last decade, many studies have tried to define the neural correlates of attention deficit hyperactivity disorder (ADHD). The main aim of this study is the comparison of the ERPs independent components in the four QEEG subtypes in a group of ADHD adults as a basis for defining the corresponding endophenotypes among ADHD population. Sixty-seven adults diagnosed as ADHD according to the DSM-IV criteria and 50 age-matched control subjects participated in the study. The brain activity of the subjects was recorded by 19 channel quantitative electroencephalography (QEEG) system in two neuropsychological tasks (visual and emotional continuous performance tests). The ICA method was applied for separation of the independent ERPs components. The components were associated with distinct psychological operations, such as engagement operations (P3bP component), comparison (vcomTL and vcom TR), motor inhibition (P3supF) and monitoring (P4monCC) operations. The ERPs results point out that there is disturbance in executive functioning in investigated ADHD group obtained by the significantly lower amplitude and longer latency for the engagement (P3bP), motor inhibition (P3supF) and monitoring (P4monCC) components. Particularly, the QEEG subtype IV was with the most significant ERPs differences comparing to the other subtypes. In particular, the most prominent difference in the ERPs independent components for the QEEG subtype IV in comparison to other three subtypes, rise many questions and becomes the subject for future research. This study aims to advance and facilitate the use of neurophysiological procedures (QEEG and ERPs) in clinical practice as objective measures of ADHD for better assessment, subtyping and treatment of ADHD.

Brain Topography of Emf-Induced Eeg-Changes in Restful Wakefulness: Tracing Current Effects, Targeting Future Prospects.

INTRODUCTION: Covering a handful of decades but spanning across two centuries, mobile phones announced the dawn of the technological revolution, standing at the forefront as its' most prominent symbol. Over the course of their sovereign dominance, human generations born with the birth of the mobile phone reached the age of maturity, while scientific community started reaching for experience-based perceptivity. AIM: The following review serves as a short-cut across a half-decade old research gap, and a clear-cut analysis on the cutting-edge knowledge of the EMF induced EEG changes. MATERIAL AND METHODS: The selection covers 28 articles about mobile phone effects on resting wakeful EEG in humans conducted over the last two decades, across three continents and 12 countries, of which 75% had positive findings. CONCLUSIONS: At present, the general protocol of a typical study includes investigations on adults (20-60 yrs) grouped in smaller samples and exposed to shorter intervals of GSM-like pulse-modulated signal (10-30 subjects/minutes). The assessment usually involves linear methods for quantitative analysis, while the results mostly revolve around posterior increase in alpha and beta frequency range. The qualitative variations, however, remain open to interpretation. Future research may benefit from multiplication of sub-specific studies leading to replication of more consistent results. The long-term and large-size epidemiologic studies, stratified by age and gender, may also improve the expected outcomes. Regarding the interpretation, non-linear methods could be employed for assessment of individual variations. The emphasis should be placed on theories/measures for better understanding of the subtle interplay between the spectral individualities and mobile phone radiation specifics.

Machine learning approach for classification of ADHD adults.

Machine learning techniques that combine multiple classifiers are introduced for classifying adult attention deficit hyperactivity disorder (ADHD) subtypes based on power spectra of EEG measurements. The analyzed sample includes 117 adults (67 ADHD, 50 controls). The measurements are taken for four different conditions: two resting conditions (eyes open and eyes closed) and two neuropsychological tasks (visual continuous performance test and emotional continuous performance test). We divide the sample into four data sets, one for each condition. Each data set is used for training of four different support vector machine classifiers, while the output of classifiers is combined using logical expression derived from the Karnaugh map. The results show that this approach improves the discrimination between ADHD and control groups, as well as between ADHD subtypes.

Are Macedonian chronic patients alexithymic?

Psychological factors have been supposed as an important link in the chain of pathogenesis and the course of many diseases, especially stress-related ones. The field of psychosomatics is concerned with the study of the mind / body relations and, in this context, to the assessment of the influence of psychological factors on bodily changes and, consequently, with the development of illness. Alexithymia, the inability to identify or label emotions, has been shown to be associated with patients with many chronic conditions. The study was performed to obtain a) normal values of TAS-20 in Macedonian healthy people and b) to compare the results with a groups of chronic patients. In this study, TAS-20 was applied as a measure of alexithymia. It was concluded that the alexithymia construct is a permanent personality trait related to neurobiological brain specifics. The construct is important for both, either as a trigger or as the conesquence of the illness. Patients with chronic diseases are more alexithymic than healthy people. In our research alexithymia has been confirmed in patients with cancer, rheumatoid arthritis and dialyzed patients as well as in patients after myocardial infarction. An alexithymia construct can influence the prognosis and outcome of the chronic disease. Anyhow, the psychological support for mediating alexithymia should be included in the therapeutic protocols of all chronic patients.

Paleoneurosurgical aspects of Proto-Bulgarian artificial skull deformations.

Paleoneurosurgery represents a comparatively new developing direction of neurosurgery dealing with archaeological skull and spine finds and studying their neurosurgical aspects. Artificial skull deformation, as a bone artifact, naturally has been one of the main paleoneurosurgical research topics. Traditionally, the relevant neurosurgical literature has analyzed in detail the intentional skull deformations in South America's tribes. However, little is known about the artificial skull deformations of the Proto-Bulgarians, and what information exists is mostly due to anthropological studies. The Proto-Bulgarians originated from Central Asia, and distributed their skull deformation ritual on the Balkan Peninsula by their migration and domination. Proto-Bulgarian artificial skull deformation was an erect or oblique form of the anular type, and was achieved by 1 or 2 pressure bandages that were tightened around a newborn's head for a sufficiently long period. The intentional skull deformation in Proto-Bulgarians was not associated with neurological deficits and/or mental retardation. No indirect signs of chronic elevated intracranial pressure were found on the 3D CT reconstruction of the artificially deformed skulls.

Neurophysical substrates of arousal and attention.

The study of arousal and attention could be of prominent importance for elucidating both fundamental and practical aspects of the mind-brain puzzle. Defined as "general activation of mind" (Kahnemann in Attention and effort. Prentice-Hall, New Jersey, 1973), or "general operation of consciousness" (Thacher and John in Functional neuroscience: foundations of cognitive processing. Erlbaum, Hillsdale, 1977), arousal can be considered as a starting point of fundamental research on consciousness. Similar role could be assigned to attention, which can be defined by substituting the attributes "general" with "focused". Concerning the practical applications, the empirically established correlation between neuronal oscillations and arousal/attention levels is widely used in research and clinics, including neurofeedback, brain-computer communication, etc. However, the neurophysical mechanism underlying this correlation is still not clear enough. In this paper, after reviewing some present classical and quantum approaches, a transition probability concept of arousal based on field-dipole quantum interactions and information entropy is elaborated. The obtained analytical expressions and numerical values correspond to classical empirical results for arousal and attention, including the characteristic frequency dependence and intervals. Simultaneously, the fundamental (substrate) role of EEG spectrum has been enlightened, whereby the attention appears to be a bridge between arousal and the content of consciousness. Finally, some clinical implications, including the brain-rate parameter as an indicator of arousal and attention levels, are provided.

Spectrum-weighted EEG frequency ("brain-rate") as a quantitative indicator of mental arousal.

A concept of brain-rate is introduced, defining it as the weighted mean frequency of the EEG spectrum. In analogue to the blood pressure, heart-rate and temperature, used as standard preliminary indicators of corresponding general bodily activations, it is proposed to use the brain-rate as a preliminary indicator of general mental activation (mental arousal) level. In addition, along with the more specific few-band biofeedback parameters (theta-beta ratio, relative beta ratio, etc.), the brain-rate could be effectively used as a general multiband biofeedback parameter.