E. Yu. Sitnikova

Thermochemistry of heteroatomic compounds. X. The thermochemistry of solution and solvation of substituted alkylphosphonic derivatives

The enthalpies of vaporization of different classes of phosphorylated alcohols and amines were determined from their enthalpies of solution in hexane and carbon tetrachloride. The enthalpies of specific (hydrogen-bond) interaction with the solvents (chloroform and pyridine) of derivatives containing X-H groups (X=O or N) in the α-position to the P=O group were determined. The results were explained in terms of the spatial structure of such compounds.

Adaptive wavelet transform-based method for recognizing characteristic oscillatory patterns

The problem concerning the automatic recognition of characteristic oscillatory patterns in multicomponent signals is investigated using the brain’s electric activity records, electroencephalograms (EEGs), as an example. It has been ascertained that recognition errors can be decreased by optimally selecting continuous wavelet transform (CWT) parameters to obtain characteristics describing the most important information on analyzed patterns. The adaptive CWT-based method for identifying the characteristic types of EEG rhythmic activity is proposed.

Automatic Extraction and Analysis of Oscillatory Patterns on Nonstationary EEG Signals by Means of Wavelet Transform and the Empirical Modes Method

The time-frequency structure and dynamics of oscillatory patterns in electroencephalograms of rats is studied by means of continuous wavelet transform and the decomposition of the signal by empirical modes. A method for the automatic selection of patterns using the empirical modes is developed. The method is applied to the study of sleep spindles, and it is shown that their dynamics depends on the regularities of on-off intermittency.

Compensatory Changes in the Brain Dopaminergic System of WAG/Rij Rats Genetically Predisposed to Absence Epilepsy

Involvement of the brain dopaminergic system in the age-related dynamics of absence epilepsy in WAG/Rij rats was examined by histological, immunohistochemical, and electrophysiological (EEG) methods. We revealed reduced expression of dopamine receptors in various brain structures prior to first manifestations of the disease (at the age of 1–3 months), reduced density of neurons in the center of nigrostriatal system (substantia nigra pars compacta) in 10-month-old rats in comparison with 1-month-old rats, and positive correlation between neural density in the substantia nigra and intensity of epileptic activity in EEG. It is hypothesized that loss of dopaminergic neurons and reduced nigrostriatal dopaminergic innervation of the brain could prevent the development of absence epilepsy in WAG/Rij rats.

Time-frequency analysis of characteristic patterns of the activity of neuron ensembles in the brain by means of continuous wavelet transform

The time-frequency characteristics of sleep spindles on EEG are studied by means of continuous wavelet transforms. Age dependence and dependence on epileptic status of animals of these characteristics was studied, the on-off intermittency in behavior of sleep spindles was found.

The Lemniscal and Paralemniscal Pathways of the Trigeminal System in Rodents Are Integrated at the Level of the Somatosensory Cortex

The studies reported here demonstrate that the projection representation of the whiskers in the somatosensory cortex in rats is the area at which afferent streams arriving via the lemniscal and paralemniscal projections interact. The responses of neurons in layers IV, Va, and Vb to mechanical stimulation of single whiskers were studied. Neurons in layers IV and Vb were found to show more frequent phasic responses (typical of the lemniscal system), while those in layer Va produced predominantly tonic responses (typical of the paralemniscal system). These characteristics of adaptive-plastic rearrangements of cortical neuron activity in response to constant stimuli may result from intracortical cooperative interactions between the lemniscal and paralemniscal projection systems, which, overall, produces a precise qualitative assessment of the perceived stimulus in its specific context.

Thermochemistry of heteroatomic compounds. Part 13. The study of interaction between the esters of aminophosphonic and dithiophosphorus acids

Abstract The calculated thermodynamical data of complex formation between some derivatives of aminophosphonic and dithiophosphorus acids have been presented in this communication. The magnitudes of the formation enthalpy, Gibbs energy, entropy and equilibrium constant of the complex formation of the mentioned interaction in i-propanol-water mixture were determined. The carried out IR spectral investigations suggested the conclusion, which has been made on the basis of thermochemical research.

Sensory information—The major factor of ontogeny

On the basis of their own data the authors postulate that the increase in sensory input during early ontogeny results in a delay in the development of the sensory systems formed earlier. In connection with this, the sensory basis of behavioral patterns becomes ineffective, causing their reorganization and the appearance of new forms of behavior. Limitation of sensory input during the critical periods of development stimulates the accelerated manifestation of behavioral patterns. However, this acceleration also has long-lasting negative effects— alterations in the processes of learning and memory in adult animals.

The Responses of Neurons of the Somatosensory Cortex to Stimulation of the Posterior Thalamus (PO) in WAG/Rij Rats Genetically Predisposed to Absence Epilepsy

In genetically predisposed WAG/Rij rats and healthy Wistar rats, we studied functioning of the paralemniscal region of the thalamo-cortical system. The responses of neurons of the somatosensory cortex to single electrical stimulation of the posterior nucleus of the thalamus were recorded in two- to three-monthold rats within the period when the epileptic activity was not developed. We revealed lower number of shortterm inhibitory responses in WAG/Rij rats as compared to Wistar rats. This may create preconditions for the spreading of spike-wave activity in the somatosensory cortex, which is an electrophysiological sign of absence epilepsy.

Intermittency of intermittencies in characteristic oscillatory patterns on epileptic electroencephalograms

The temporal dynamics of characteristic oscillatory patterns in an epileptic EEG are analyzed. A statistical analysis of time gaps between oscillatory events on EEG records is performed following the automatic segmentation of EEG signals. Both sleep spindles and spike-wave discharges exhibit intermittency dynamics, and the collective dynamics of these patterns is characterized by the intermittency of intermittencies.