A theoretical approach to understanding of the vestibular perception organization in microgravity condition.

This paper should be viewed as a part of our attempts to arrive at a quantitative understanding of some contradictory experimental phenomena in the vestibular perception. The most popular remains the Steinhausen's model of perception, in which the endolymph circulation, caused by the angular acceleration, is "measured" by the displacement of cupulae diaphragm. Though displacements of the cupulae top were experimentally observed, the thorough mathematical analysis shows that the applicated stop-stimuli were too much over the range of adequate stimulation conditions, so the cupulae was teared off from its normal position. The more natural mechanism of perception was proposed by McLaren & Hillman. It was experimentally demonstrated that the cupulae diaphragm remained margin attached during the normal stimulation conditions only with its bottom moved according to the value of the applicated angular acceleration. A question only arises, how will be the hair cells excited by low level stimulation, when elastic deformations of the cupulae are small and there is no visible shift of the cupulae bottom? The response is to find in the third mechanism formulated by Schmaltz, which connected the excitation of hair cells with the process of endolymph diffusion through the cupulae towards the subcupulae space.

[The significance of rhythmic contractile activity of the arteries for the regulation of the rate of blood flow]. / O znachenii ritmicheskoi sokratitel'noi aktivnosti arterii dlia reguliatsii skorosti krovotoka.

The effect of rhythmic contractile activity of the rat mesenteric arteries upon the blood flow velocity, was studied. The vasomotion was induced both by a direct stimulation of vascular motor nerves and a nociceptive stimulation. The wave of the vasomotion was shown to spread towards the periphery of the arterial bed irrespective of the way of influencing. The mathematical model of the vessel as a peristaltic pump working against the background of a constant shifting of the pressure with the contraction wave's parameters measured during the experiments, revealed that the blood flow velocity equally depended on the amplitude and the velocity of spreading of the rhythmic contractions. The experiments suggest involvement of the sympathetic nervous system in the control of the vasomotion's parameters and, consequently, of the blood flow velocity in the vessels during latters' rhythmic contractile activity.

[Horizontal optokinetic nystagmus in th pigeon during static tilts in the sagittal plane]. / Gorizontal'nyi optokineticheskii nistagm u golubia vo vremia staticheskikh naklonov v sagittal'noi ploskosti.

The mode of symmetrical position-related otolith influences modified the parameters of optokinetic nystagmus in pigeons. The symmetry of temporonasal-nasotemporal responses was due to increase in the NT-stimulation efficiency. The parameters of optokinetic nystagmus seems to depend on the direction of the otolith membrane shifts.

[Trans-sorption as an important mechanism of molecular transport in biological systems]. / Transsorbtsiia kak vazhnyi mekhanizm molekuliarnogo transporta v biologicheskikh sistemakh.

The mechanism of trans-sorption was shown to be based on mobile adsorption of various substances at specific and unspecific sites localised in spatially organised systems integrated within premembrane structures. Some specifics and possible physiological significance of trans-sorption are discussed using mathematical models of nutrients transfer across autonomous premembrane layer in the small intestine.

[Spatial selectivity of vestibular receptive fields of cerebellar Purkinje cells towards the orientation of angle accelerations]. / Prostranstvennaia izbiratel'nost' vestibuliarnykh retseptivnykh polei kletok Purkin'e mozzhechka k orientatsii uglovykh uskorenii.

Using microcaloric stimulation of semicircular canals of the frog vestibular apparatus parameters of orientation sensitivity of the receptive fields of the cerebellum Purkinje cells towards angle accelerations were studied. A change of this sensitivity depending on the value of acting angle acceleration was shown.

[A model of the regulation of involuntary movements of the eye]. / Model' sistemy upravleniia neproizvol'nymi dvizheniiami glaz.

Within the scope of the concepts on the look control mechanism, i. e. the system of interrelated control of head and eye movements a mathematical model is considered which described the control system over eye involuntary movements with quadratic criterion of its work quality. Assuming the optimal character of the control system under study and taking into account the experimental data on the eye movements parameters the relationship between the parameters of the criterion introduced and retinotopic relation of a locus of lateral geniculate is estimated.

[Interaction between the otolithic organ and semicircular canals of the vestibular apparatus in the system of directional orientation of man in space]. / Vzaimodeistvie otolitovogo organa i polukruzhnykh kanalov vestibuliarnogo apparata v sisteme uglovoi stabilizatsii cheloveka v prostranstve.

A mathematical model is suggested of the biological system of angular stabilization in space relative to the local vertical using measures whose parameters are near to the parameters of the semicircular canals and otolithic organ of the man. On the basis of computer simulation for physiologically adequate external stimulations contribution of each of measures to the total process of angular stabilization is evaluated.

[Role of the body of the skate in initial processing of electroreceptor system signals]. / Rol' tela skata v pervichnoi pererabotke signalov élektroretseptornoi sistemoi.

Possible space mechanisms of information conversion processes with Lorenzinian ampullary apparatus during detection of the dipole electric field were studied using mathematical modelling methods. The stationary voltage distribution in the nonuniform media was calculated by numerical methods. The skate body was simulated by a thin disk. If the dipole axis lay in the disk plane potential distortions near the disk were negligibly small. In other cases the electrical field energy absorbed by ampullary groups was dramatically reduced. It is supposed that body tissues serve as a space filter of the electroreceptive system.

[Electroreceptor characteristics of elasmobranchs with pint sources of the electric field]. / Analiz kharakteristik élektroretseptorov plastinozhabernykh rib s pomoshch'iu tochechnykh istochnikov élektricheskogo polia.

Using mathematical modelling methods and experimental data possible space mechanisms of information conversion processes with Lorenzinian ampullary apparatus during detection of the dipole electric field were studied. The space selectivity of the ampullary groups was shown and its biological significance is discussed.

[Reaction of the human vestibular apparatus to periodic effects of the ship-rocking type]. / Issledovanie reaktsii vestibuliarnogo apparata cheloveka na periodicheskie vozdeistviia tipa kachki korablia.

Reactions of the semicircular canals to periodic effects of the ship rolling type have been studied, using a mathematical model. The data obtained give evidence that during the above effects linear combinations of reactions of all semicircular canals may describe changes in the angular velocity of man's movement in an absolute (static) space. Besides, the common segment of the vertical semicircular canals (the common limb) allows a more accurate description of time changes in angular velocity. The mathematical model has demonstrated the dependence of absolute angular velocity as approximated by the semicircular canals from head orientation as related to the body. In addition to general discussions about rolling effects on the semicircular canals, the paper presents calculations of such reactions as applied to a specific object, i. e. a medium-size trawler.

Membrane and intracellular hydrolysis of peptides: differentiation, role and interrelations with transport.

The possible relative importance of the membrane and intracellular peptidases of the enterocytes in splitting dietary peptides to amino acids has been analysed. On the anoxic criterion, membrane hydrolysis was found to be predominant. Model experiments revealed cooperative interactions between the membrane enzyme and the coupled transport system. This cooperativity allows the main characteristics of oligomer transport to be described in terms of membrane digestion. Comparison of the behaviour of membrane and intracellular peptidase under different conditions has shown that the former are largely involved in digestion and the latter in intracellular metabolism. It is suggested that the efficiency of the membrane system is high enough to account for the hydrolysis of protein, especially taking into account the stimulation of enzyme processes in the brush border that occurs after ingestion of protein and carbohydrate. A sequential model based on the concept of three interacting enzyme layers (glycocalyx, lipoprotein membrane and cytosol) is presented.

[Transformation of angular accelerations by the semicircular canal system of the vestibular apparatus]. / O preobrazovanii uglovykh uskorenii sistemoi polukruzhnykh kanalov vestibuliarnogo apparata

Transformation of angular accelerations by the system of three semicircular channels is considered which takes into account mutual influence of vertical channels through a common crus.