Uspekhi Fiziologicheskikh Nauk最新文献

This review presents summarizes data on the structural and functional organization of the GABAergic system of the brain, mechanisms of GABAergic transmission, about the characteristics of GABA-receptors and GABAergic inhibition forms. Reviewed issues of involvement of GABA inhibitory neurotransmitter and various types of GABA-receptors in epileptogenesis. The experimental and clinical data testifying to an important role of GABA and its receptors in an epileptogenesis are presented.

We suggest a mechanism for creating receptive fields of neurons in the primary auditory cortex (A1) and ventral part of the medial geniculate body (MGBv) in which the "direct" pathway through the basal ganglia participates. Dopamine released in the striatum in response to appearance of a sound tone promotes the induction of LTP of the efficacy of "strong" inputs and LTD of "weak" inputs from A1 to striatonigral cells due to activation of D1 receptors on these cells. Subsequent reorganization of neuronal activity in the network A1 field--basal ganglia--MGBv--A1 field results in a disinhibition of MGBv neuron activity, contrasting amplification of neural representation of a sound tone in MGBv and A1 field, and sharpening the receptive fields. Plastic shift of neuronal receptive fields is based on modification of efficacy of synaptic transmissions between the neocortex and striatum, and between all units of thalamocortical loop. Synaptic modification could be promoted by synchronization of activity of neurons which is based on the high-frequency oscillations relying on interdependent functioning of inhibitory cells in the considered loops.

A hypothetical mechanism is suggested for processing of complex sounds and auditory attention in parallel neuronal loops including various auditory cortical areas connected with parts of the medial geniculate body, inferior colliculus and basal ganglia. Release of dopamine in the striatum promotes bidirectional modulation of strong and weak inputs from the neocortex to striatal neurons giving rise to direct and indirect pathways through the basal ganglia. Subsequent synergistic disinhibition of one and inhibition of other groups of thalamic neurons by the basal ganglia result in the creation of contrasted neuronal representations of properties of auditory stimuli in related cortical areas. Contrasting is strengthened due to a simultaneous disinhibition of pedunculopontine nucleus and action at muscarine receptors on neurons in the medial geniculate body. It follows from this mechanism that involuntary attention to sound tone can enhance an early component of the responses of neurons in the primary auditory cortical area (50 msec) in the absence of dopamine due to a disinhibition of thalamic neurons via the direct pathway through the basal ganglia, whereas voluntary attention to complex sounds can enhance only those components of responses of neurones in secondary auditory cortical areas which latencies exceeds latencies of dopaminergic cells (i.e. after 100 msec). Various consequences of proposed mechanism are in agreement with known experimental data.

Periaqueductal gray matter of the midbrain (PAGM) plays a crucial role in the regulation of pain sensitivity under stress, involving in the stress-induced analgesia. A key hormonal system of adaptation under stress is the hypothalamic-pituitary-adrenocortical (HPA) axis. HPA axis's hormones, corticotropin-releasing factor (CRF) and glucocorticoids, are involved in stress-induced analgesia. Exogenous hormones of the HPA axis, similarly to the hormones produced under stress, may cause an analgesic effect. CRF-induced analgesia may be provided by glucocorticoid hormones. CRF and glucocorticoids-induced effects on somatic pain sensitivity may be mediated by PAGM. The aim of the review was to analyze the data of literature on the role of PAGM in the regulation of somatic pain sensitivity under stress and in providing of CRF and glucocorticoid-induced analgesia.

Cl(-)-transport systems in cell membranes from various origins (including neurons) play an important role in different processes of their vital functions. Various transport mechanisms involved in the maintenance of intracellular concentration of Cl- that differs from concentration equilibrium have been considered. This review provides the biochemical properties of the GABA(A)-coupled Cl-/HCO3(-)-ATPase which is a candidate for an novel primary active system in neuronal membranes. Special emphasis has been placed on a review of the prerequisites for the existence of the GABA(A)-coupled ATPase. This work provides data for the benefit not only functional but also the alleged structural coupling of the enzyme with GABA(A)-receptors. It is concluded on the importance of the found ATPase in primary active transport processes across the plasma membrane of neuronal cells with different level of the organization.

Optogenetics--new method which enables the control of selected cell type activity using light. This method significantly enhances the capabilities of modern neurobiology. In the review, the general concept of optogenetics and recent results and prospects of application of this approach in psycho-behavioral studies are discussed.

This review contains modern information about the representation of serotoninergic system in the Amygdala with detailed characteristics of the localization of serotonine fibers and serotonine receptors in nuclear and paleocortical structures. These data indicate the joint participation of serotonine and sex steroids in the regulation of the neuroedocrine function of Amygdala, which have a modulating effect on the secretion and release gonadotropine centers and sexual behavior centers in the hypothalamic area of the brain. The survey also gives information about changes in the exchange of serotonine in the Amygdala's structures in the process of alimentary, maternal, aggressive-defensive and emotional behavior. Systematizes the data on the role of serotonin and sex steroids in the mechanisms involved in the stress response of Amygdala, and its participation in the formation of mood, emotions and the genesis of depression. Presented data on changes in morphometric characteristics of brain structures caused by polymorphic variants of genes of serotoninergic systems and data on the asymmetry of its content.

Endothelium is an important regulator of selective permeability of the vascular wall for different molecules and cells. This review summarizes current data on endothelial barrier function. Endothelial glycocalyx structure, its function and role in the molecular transport and leukocytes migration across the endothelial barrier are discussed. The mechanisms of transcellular transport of macromolecules and cell migration through endothelial cells are reviewed. Special section of this article addresses the structure and function of tight and adherens endothelial junction, as well as their importance for the regulation of paracellular transport across the endothelial barrier. Particular attention is paid to the signaling mechanism of endothelial barrier function regulation and the factors that influence on the vascular permeability.

The review contains recently finding mechanisms of aging brain and of age-associated imbalances of architecture and functions of brain neural systems. The compensatory resources of a brain and the methods of its cognitive training influencing the integrity and development of intellectual functions are described. It is shown meaning life style in dynamics of brain aging.

In the modern neurophysiology opinion was confirmed that the electrical signals of the brain in the frequency band from DC to electroencephalogram recorded with metallic conductors of inert metal implanted in the brain are formed solely by changes in the electric field of the brain. This paper presents a review of the literature and our own data, according to which the formation of these signals involves two factors. One factor is a change in the charge of the electric double layer electrode having a capacitor property and change the value of its charge with changes in the electric field volume conductor--the brain. Another factor is an electrochemical signal is defined by local changes in the redox potential (E) neuronal-glial populations surrounding the electrode. The paper provides an overviews the electrical and electrochemical properties of the electrodes of the inert metals used in electrophysiology. It is shown that each of these factors has the characteristic parameters over time and amplitude. The data of own studies of local changes in E cortex accompanying brain's response to the implantation of electrodes in the brain's cortex, the natural behavior of animals in the wake-sleep, integrative brain function and effect of pharmacological agents. These results give evidence of the highly informative study of local changes in brain E in order to study energy metabolism in the brain of waking animals, and lay the foundation for the study of local changes in brain energy metabolism in free animal behavior.