Sequential method for fast neural population activity reconstruction in the cortex from incomplete noisy measurements.

During recent years there has been a growing interest in stochastic dynamic neural fields employed for modeling and predictions in biomedical and technical systems. In this paper, given some incomplete noisy data available from sensors, we propose and explore a state estimation method for fast restorations of membrane potential in the cortex based on such measurements and the Amari equation used for simulations of neural population activity in a stochastic setting. Our novel technique relies upon a Galerkin-type spectral approximation utilized within the conventional state-space approach. Translating a stochastic system into its state-space form creates a straightforward and fruitful way to the data-driven parameter estimation, filtering, prediction and smoothing. The present study is particularly focused on establishing a nonlinear stochastic Galerkin-spectral-approximation-induced system of large size, which is further estimated by the traditional extended Kalman filter (EKF). The efficiency of calculations is the main purpose of our research. That is why the fast filtering solution devised is based on processing the incoming data incrementally, that is, by processing measurements one at a time, rather than handling them as a unified high-dimensional vector. Such sequential filters suit well for dealing with large data sets as well as with real-time on-line computations. Also, their derivation and substantiation is of great interest in the context of neural network training because of large stochastic systems arisen there. In comparison to the batch filtering, our novel algorithm reduces the computational cost of membrane potential reconstructions in terms of the amount of grid nodes N accepted in the underlying spacial discretization, significantly. Apart from its computation efficiency, this sequential method is more robust to round-off errors committed within a computer-based finite precision arithmetics than the classical EKF because of the (N × N)-matrix inversion elimination from such membrane potential calculations. The superior performance of our technique is examined and confirmed in comparison to the batch one on two known scenarios in the dynamic neural field modeling.

Effects of genetic variations in the dopaminergic system on fatigue in humans: gender aspects.

Changes in the functional status under the effect of intense mental exercise were studied in carriers of different variants of DAT1, DRD2, and COMT genes. The volunteers (n=140) performed 3-h monotonous mental work (information processing and logical problem solving). The degree of fatigue was evaluated before and after exercise by the HAM (Health status-Activity-Moods) and AMF (Acute Mental Fatigue) questionnaires. A significant relationship between the DAT1, DRD2, and COMT gene polymorphism and changes in the mental sphere status were revealed. The effects of these polymorphisms were the most pronounced in girls. The results are discussed within the framework of hypothesis on the effects of changes in the phasic/tonic dopamine proportion on the studied functions.

[Genetic and social factors in developing of aggression].

The association of 5-HTTLPR gene polymorthism and aggression was studied in control group of males and females and in the athletes. The sport activities were found to decrease the aggression: the effect persist for the synchronized swimmers and for the wrestlers. Control group of males were characterized by higher aggression scores (Assault, Negativism, Suspicion and Verbal aggression scales of Buss-Durkee Hostility Inventory) compared to females. For all female-subjects irrespective of sport activities and age, the association between the variants of 5-HTTLPR gene and the Indirect Aggression and Negativism scores were found: carries of SS genotype has higher scores on Indirect Aggression and lower scores on Negativism. For the males the association was different: The averaged Hostility scores were higher for the carriers of LL-genotype. The brain processes, presumably underlying the association between aggression and 5-HTLPR gene, were studied in male control group. The increased MMN component of ERP, which responsible for the automatic change detection, and decreased P3a component, related to involuntary attention and cognitive control were found in LL-carries. It might be considered as a sign that SS-carries process the information with more cognitive resources. Probably they perceive the stimulus as more complicated, which lead to activation the additional resources of frontal cortex. It might be also suggested that the carries of SS-genotype tend to deeper processing of the incoming information. Probably, it is this more "serious" analysis of external information, which underlies the rejection of impulsive aggressive actions.

Gender effects on association of serotonin transporter gene polymorphism with symptoms of central fatigue.

In order to test the "serotonin" hypothesis of the genesis of central fatigue, we studied association between genotype and fatigue (3-hour mental workload consisting of information processing and logical task solution) using analysis of variance for different indices (well-being, activity, mood, mental fatigue index). It was concluded that young men with serotonin deficit (LL genotype) and girls with serotonin excess (S genotype) were less tolerant to long-lasting mental workload. Thus, we confirmed that the degree of central fatigue depends on the function of the serotonin system and revealed gender differences in adaptive capacities of carriers of different variants of serotonin transporter.

Role of renin-angiotensin system in the formation of emotional state in humans.

We studied the effect of angiotensin-converting enzyme gene polymorphism on human emotional state in humans (189 athletes and 212 volunteers not engaged in sport activity). The distribution of angiotensin-converting enzyme genotypes was estimated. The dependence of aggression on age, sex, and professional activity was evaluated. This polymorphism was associated with physical aggression in female synchronized swimmers. Physical aggression in II genotype carriers was lower than in D allele carriers. Our results indicate that individual differences in aggression depend on professional activity and are genetically determined.

Effect of functional catechol-O-methyltransferase Val158Met polymorphism on physical aggression.

Genetic and psychological analysis of the relationships between catechol-O-methyltransferase Val158Met polymorphism and various types of aggressiveness was performed in 114 women. Dispersion analysis revealed significant association of ValVal genotype with elevated physical aggression.

Genetic markers of predisposition to increased anxiety.

Associations of functional polymorphism in genes of dopamine receptor DRD2, dopamine transporter DAT, and dopamine degrading enzyme COMT with variations in anxiety sensitivity threshold were studied. On the basis of genetic and psychological analysis, an attempt was undertaken to evaluate the relationship of DRD2, DAT and COMT genotypes with values obtained using different anxiety scales. It was found that carriers of VA1(+)9(+) genotype exhibit increased anxiety and significantly differed from individuals with other genotypes. The results were illustrated with model of dopamine diffusion in the extracellular space of the striatum in carriers of different genotypes.

[Genetic basis of time perception in athletes].

The association between the subjective time perception and polymorphism of some genes, regulating activity of serotonin and dopamine, was studied in 89 synchronized swimmers. COMT gene, responsible for dopamine destruction, influences on reproduction of short time intervals (1-2 s). 5-HT2A and MAOA genes, regulating activity of serotonin, influence on subjective time flow. 5-HTT and COMT genes, regulating activity of serotonin and dopamine respectively, are related with accuracy of orientation in time. Association of time perception with different genes and mediators suggests different perception mechanisms, in different time ranges, in concordance with the previous physiological studies. The current study reveals that these physiological mechanisms have different molecular-neurochemical basis that helps to overcome the gap between the investigation on systemic and molecular levels.

Preservation of native properties of mitochondria in rat liver homogenate.

A protocol is developed for preparation of concentrated rat liver homogenate preserving assemblies of mitochondria in isotonic KCl under 0 and 15 degrees C. Assemblies preserve ability for self-organization during storage in homogenate. All key energy functions of mitochondria can be investigated in such a homogenate. Oxidative phosphorylation and membrane potential are stable for 5-7 h and can be still observed on the next day. Substrate-level phosphorylation is better pronounced for mitochondria in KCl than in sucrose medium while Ca2+ capacity is greater and lipid peroxidation is much lower. Sucrose addition impairs these functions. The rate of phosphorylating respiration is lower in large assemblies and higher in small. Transition from large to small assemblies corresponds to the transition from quiescent state of animal to adrenaline induced active state. The proposed method is particularly convenient for clinical investigations with small bioptates.

[Simulation of the formula of emotions: subjective and objective quantitative indices]. / Modelirovanie formuly émotsii: sub''ektivnye i kolichestvennye pokazateli.

Nonlinear dependence between the emotion intensity and main emotion components: the value of need and probability of its satisfaction is confirmed by the analysis of subjective and objective indices during mental reproduction of emotional situations. The dependence suggests a possibility of application of some its linear analogs in a certain range of changes in the intensity of need and possibility of its satisfaction.

[Structure and negative sequelae of medical errors in care for angina pectoris]. / Struktura i negativnye sledstviia vrachebnykh oshibok pri okazanii meditsinskoí pomoshchi bol'nym stenokardieí.

12 cardiologists trained as experts in assessment of medical care quality (MCQ) made a computer-assisted expertise of the care rendered to 110 anginal patients. Of these 68 patients had angina of effort (AE) and 42 had unstable angina (UA). This made up 10% of annual number of anginal patients treated in the cardiological clinic in 1996. Medical errors were of the same type in both the groups. Inadequate collection of information, erroneous diagnosis, treatment, continuity occurred in 50, 30, 15 and 5% of all the errors, respectively. Negative effects of the errors were mild (less seriously suffered AE patients), but led to waste of health service resources.

[Prevention and treatment of purulent inflammatory complications of open craniocerebral trauma with decamethoxine ]. / Profilaktika i lechenie gnoino-vospalitelnykh oslozhnenii otkrytoi cherepno-mozgovoi travmy s ispolzovaniem dekametoksina.

In the work based on the analysis of observation of 154 sufferers with an open craniocerebral trauma, the positive therapeutic and preventive action of agueous solutions of decamethoxine is shown.