Effect of epicortical stimulation on depolarization of primary afferents in rats during early postnatal ontogenesis

Studies have been made on the parameters cord dorsum potentials (CDP) during stimulation of sensorimotor cortex in rats during first month of their postnatal life. First CDP were recorded from the 10th day, their latency being equal to about 80 msec, amplitude--65-70 microV, duration--more than 200 msec. During postnatal life of rats, the latent period decreases twice, the amplitude increases more than 3-fold, whereas the duration remains almost unchanged. These data indicate maturation of the descending pathways to the spinal cord, the increase in the propagation rate along these pathways and formation of segmentary mechanisms responsible for the generation of CDP. The effect of stimulation of the sensorimotor cortex on depolarization of primary afferent was also investigated. It was found that from the 2nd week of postnatal, life, formation of supraspinal control of afferent impulsation takes place.     

Ultrastructural and functional changes in the myocardium and coronary vessels after massive blood loss

The ultrastructure of cardiomyocytes and circulatory bed has been compared to transmembrane cAMP-dependent Ca2+ transport in experiments on the hearts of 14 dogs immediately after massive blood loss. The results an hour after non-compensatory hemorrhage have shown extra- and intracellular myocardial edema, central destruction of sarcomers, steep increase in the volume of agranular sarcomplasmic reticulum and T-system, different degree of damage of other organoids, and also disturbances in the ultrastructure of venous capillary and postcapillary section. The biochemical techniques used have shown a decrease in Ca2+ transporting ability of sarcolemma due to its AMP-dependent regulation of cardiomyocytes. Excessive Ca2+ storage in cytosole promoted the appearance of "constriction bands" in myofibrils.     

Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1?–?4, each week with 3 dams with each litter size. Milk intake was determined over a 48?h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2?g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1?g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg^0.75 and the efficiency of utilization of ME for body gain (k_g) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (k_g) in suckling mink kits.     

The effect of scopolamine on the spatial organization of rat cortical potentials

The influence of scopolamine (1 mg/kg, i.p.) on the spatial organization of the neocortical electrical activity was studied in rats. A decrease in the spectral power and coherence of brain potentials in the range of the dominant theta-rhythm peak (6.00-7.25 Hz) and their increase in the adjacent low-frequency band were observed. Both indices were decreased in the wide beta band (19.00-30.00 Hz). The described changes took place over the whole areas of the right hemisphere and parieto-temporal region of the left hemisphere. The obtained results are discussed with respect to the role of the cholinergic brain system in the higher nervous activity.     

Characteristics of EEG signs of anxiety in human

Influence of anxiety (tested by Luscher) on the spatial organization of brain electrical activity was studied using multichannel EEG recording. In subjects with a high-level of anxiety, the level of coherence and spectral power of some high-frequency EEG components was higher in the parieto-temporal regions of both hemispheres than that in the opposite group. Solving the inverse problem (classification of individuals with one of the groups) made it possible to work out the criteria of automated evaluation of the anxiety level at the preclinic state of neuropsychic disorders. The EEG signs of the influence of increased anxiety on psychophysiological and cognitive processes and autonomic functions were analyzed. The EEG signs of increased anxiety in animals (rats) and humans were compared and some similarity of the spatial-frequency organization was revealed. The main difference consists in a greater activation of the left parieto-temporal area in humans, which is interpreted as a morphofunctional basis of verbalization of anxiogenic stimuli.     

In search for neurophysiological criteria of altered consciousness

Neurophysiological approaches to brain mechanisms of consciousness are discussed. The concept of spatial synchronization of nervous processes developed by M.N. Livanov is applied to neurophysiological analysis of higher brain functions. However, the spatial synchronization of brain potentials is only a condition for information processing and does not represent it as such. This imposes restrictions on conclusions about the neural mechanisms of consciousness. It is more adequate to use the concept of spatial synchronization in views of consciousness as a psychophysiological level along with sub- and superconsciousness in three-level structure of mind according to P.V. Simonov. Forms of consciousness interaction with other levels concern the problem of altered consciousness and may be reflected in various patterns of spatial organization of brain potentials.     

Analysis of interhemispheric asymmetries in the space-time organization of human cortical potentials

The study of spatial organization of human cortical potentials with multichannel recording (48 leads) has shown, that different functional conditions of brain (quiet alertness, excitation after caffeine administration, intellectual strain, negative emotional shifts, inhibition after administration of neuroleptics) are accompanied by synchronization changes in the left and right hemispheres specific of each brain condition. Similar shifts may be recorded both in states similar by their phenomenological characteristics (after administration of caffeine and during intellectual strain) and during the opposite levels of alertness (emotional strain and administration of neuroleptics).     

Gender differences in chronic alcoholism: EEG analysis

Comparative analysis of spatial organization of cortical biopotentials of men (n = 120) and women (n = 75) suffering from alcoholism and persons without addiction to alcohol (control groups) was carried out. Gender differences in the EEG spatial parameters under study (linear spatial synchronization in the brain cortex, non-linear spatial disorder, EEG coherence, and spectral power) were shown to be markedly less pronounced between the control groups (68 women and 85 men) than between the alcohol addicts. The obtained data allow us to explain the known fact of more serious and "malignant" character of alcoholism in women than in men in terms of neurophysiology. In alcoholics, the synchronization of low-frequency oscillations (delta and theta) was higher, whereas the synchronization of the higher-frequency spectrum part (beta1 and beta2) was lower in women than in men. This fact can be a neurophysiological basis of more progredient inhibitory-degenerative processes in women.