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Biomedical subjects

F N Makarov

Publications and source records attributed to F N Makarov.

At least 37 records · Page 2Linked to original sources
PubMed2003

[Morpho-functional characteristics of lens ciliary body as a key mechanism of accommodation in human eye].

With the aid of ophthalmological, morphological, biomechanical and regulation theory methods the inconsistency of prevalent concepts on the functional interpretation of morphological structure of ciliary zonule was demonstrated and the scheme of functioning of its elements matching clinical and physiological observations was proposed. The role of anterior and posterior portions of ciliary zonule appears to be functionally essential and consistent with accommodation mechanism proposed by Helmholtz, while the role of cilioequatorial fibers of ciliary zonule is functionally auxiliary. Morphological and constructive peculiarities of ciliary zonule structure confirm the validity of Helmholtz concepts of accommodation mechanism.

Accommodation, Ocular↗
PubMed2003

[Orderly structural organization of intrahemispheric interzonal connections in the cat visual cortex].

The study was aimed at morphometric analysis of cluster organization of neurons, forming interzonal cortico-cortical connections within the visual cortex. The study employed the technique based on horseradish peroxidase retrograde transport and methods of mathematical analysis of spatial distribution of labeled cells. The quantitative characteristics of cell distribution were obtained including cluster volume and linear dimensions, distances between their centers of gravity, periodicity and distribution along cortical surface. Age-related peculiarities in the distribution of initial cells of cortical interzonal connections were found. It was demonstrated that adult cluster organization pattern was established by the end of the second postnatal month. Quantitative differences in the spatial distribution of neuronal groups in the visual cortical areas 17 and 18 were determined.

Animals↗
PubMed2003

[Disorders of cognitive processes in simulation of Alzheimer's disease in monkeys].

Two groups of monkeys were learned to differentiate stimuli with different types of information and to make a spatial choice. Characteristics of the operative memory were revealed in the delayed differentiation tasks prior to and after administration of p75-saporin (I group) and saline (II group). For the first time the Alzheimer disease in monkeys was shown to entail a deficit of operative memory due to disorders in the sensory and cognitive components of the memory. The degree of reduction of the correct decision making was shown to depend on the delay duration and the type of visual information. Following the saline administration, no significant changes occurred in the monkeys (II group). The data obtained suggest that structural-functional organisation of the cholinergic and noradrenergic mechanisms predetermining the sensory processing, differs from those involved in decision-making.

Alzheimer Disease↗
PubMed2003

[Interaction between sensory and cognitive processes in visual recognition: the role of the associative areas of the cerebral cortex].

Monkeys were taught to differentiate stimuli with different types of information and to perform a spatial choice. Development of Alzheimer's disease in experimental monkeys entailed a deficit of operative memory, a considerable enhancement of entropy related to correct decisions. In control monkeys, no significant changes of these characteristics occurred. In monkeys, following a bilateral removal of the sulcus principalis, the 7th field, or both, the operative memory deficit was also determined by two components. The specifics of disorders in the operative memory due to Alzheimer's disease suggest that cholinergic mechanisms determining the sensory processing differ from those involved in decision-making. The structural-functional organization of interaction between sensory and cognitive processes controlled by the motivation and attention system, is discussed.

Animals↗
PubMed2003

[Cortical neuronal connections and reconstruction of visual space].

We investigated distribution of retrograde-labelled cells in cortical areas 17, 18, and the transition zone 17/18 of both hemispheres in cats after microiontophoretic horseradish peroxidase (HRP) injections into the single cortical columns of area 17, 18, 19 or 21a. On the base of clustered pattern of intrinsic labelling, asymmetric location of labelled callosal cells that was associated with the appropriate pattern of labelling in layers A and A1 of lateral geniculate nucleus, we suggest that cortical neuronal connections are eye-specific and may provide for each eye a separate binding of visual hemifields. After HRP injections into columns of area 19 or 21a, the disparate inputs from areas 17, 18 and transition zone 17/18 were revealed. Such connections may provide a local depth information and the selection of stereoscopic surfaces in central sectors of visual space.

Animals↗
PubMed2002

[Structure of reciprocal connections in visual cortical areas 17 and 18 in cats].

Single cortical columns of areas 17, 18 in the cat were microiontophoretically injected with horseradish peroxidase. Spatial and laminar distributions of retrogradell labelled cells in both areas were investigated. Following injections in area 17 or in area 18 the labelled cells' region in area 17 was elongated (in a tangential plane) along the representation of visual field horizontal meridian. However the labelled cells' region in area 18 was elongated along the representation of vertical meridian. Such projection patterns appear to be common in these cortical areas throughout the central 10 degrees on various elevations (from -40 degrees to +10 degrees) of the visual field representation. Thus the spatial arrangement of intrinsic and extrinsic connections in each area coincides, at the same time in area 17 they are orthogonal to area 18. The following visual information exchange scheme may be suggested. Area 17 may supply the area 18 with more detailed information on the horizontal component of the visual image, and in the opposite direction the information on the vertical component of the same image may be supplied.

Animals↗
PubMed2002

[Functional specifics of cortical associative regions participating in learning to differentiate visual information in monkeys].

In 3 groups of monkeys: intact, those with their 7th field bilaterally removed, and those with bilateral removal of the sulcus principalis, functional specifics of the cortex' associative areas were studied. Removal of the 7th field practically does not affect processes of training for images with such features as spatial frequency, colour, and images of animals, but considerably impairs the learning characteristics in visual differentiation of objects' size and spatial interrelationships among objects. Removal of the sulcus principalis considerably impairs the characteristics of differentiation of objects' size and spatial interrelationships among them, as well as differently coloured stimuli. In both these groups, the stable motor response term and the probability of refusal increase. The data obtained suggest that the sensory processing results in forming a few (at least three) functional visual informational flows with which different cortical areas operate.

Animals↗
PubMed2001

[Morphological analysis of the formation of cluster organization of neurons, forming the corticocortical connections in the cat visual cortex in early postnatal ontogenesis].

The development of cluster organization of neurons forming direct interzonal associative projections from striate cortex (area 17) to extrastriate area 21a in cat was studied by a technique of horseradish peroxidase retrograde transport. Reconstruction of cortical region containing retrogradely labeled neurons was performed using continuous serial sections of the brain. The analysis of spatial organization was done and quantitative characteristics of distribution pattern of initial corticocortical neurons in striate cortex in kittens were obtained. Interzonal connections were detected since 14th postnatal day. Neuronal cluster organization started forming after day 21 while its pattern became similar to that in the adult animal both qualitatively and quantitatively by the end of the 2nd postnatal month, that is somewhat later than it was previously thought. The data obtained also demonstrate the age-dependent decrease in the convergence of the striate cortex projections to area 21a associated with the reduction of the area, occupied by initial neurons.

Animals↗
PubMed2000

[A morphological analysis of the cluster organization of the cortico-cortical neurons in area 17 of the cat visual cortex].

Spatial organisation and quantitative features of cortico-cortical neurons in area 17 that project to area 21a of cat visual cortex were investigated. We used the HRP technique and two-dimensional reconstruction from serial sections of brain. Pattern of distribution of labelled cells in some regions of areas 17 and 18, on the lateral and medial surface of the brain were analysed. The data about cluster organisation of cortico-cortical neurones, localisation, layer distribution and density of neurons were obtained.

Animals↗
PubMed2000

[The spatial distribution of the horizontal connections in area 18 of the cat cerebral cortex].

Spatial distribution of horizontal inner links in field 18 of cat cerebral cortex was studied after microiontophoretic administration of HRP into a certain cortical column. HRP labelled cell location and their distribution in plane of cortex surface and sagittal and frontal planes were detected. Ellipsoid shape and rostrocaudal direction of the area of labelled cells was demonstrated irrelevant to the column localization in field 18 (stereotaxic coordinates of the columns studied are from P4 to A14). Thus, topography of the field 18 inner links was coordinated with its macrotopography, detect established electrophysiologically.

Animals↗
PubMed2000

[The role of the prefrontal and parietal cortex in learning and memory in monkeys].

Removal of the 7th field of parietal cortex and sulcus principalis of prefrontal cortex did not affect learning processes for images with such properties as spatial frequency, orientation, geometrical form, but worsen learning characteristics in visual differentiation of spatial information making the learning processes unstable, longer and below the 85% level. Removal of sulcus principalis also affects learning of differentiation among various colour stimuli. The short-term memory in these monkeys are also much worse than in intact animals. A scheme of learning involving interacting sensory and cognitive processes controlled by motivation system, is proposed.

Animals↗
PubMed2000

[Spatial organizations of projections from area 18 to area 17 in the cat visual cortex].

Spatial distribution of efferent neuronal connections from area 18 to area 17 in the cat was investigated using the microiontophoretic horseradish peroxidase injections in a single cortical columns of area 17. The localization of rertogradely labelled cells in area 18 was determined and plots of labelled cells distribution in the plane of cortical surface, in the sagittal and in the frontal planes were done. It was shown that neuronal connections from area 18 to the single column in area 17 are elongated (in the cortical surface plane) in the same rostrocaudal direction, along the representation of visual field vertical meridian, just as the intrinsic horizontal connections in area 18. This findings demonstrate the spatial correspondence between efferent and intrinsic connections distributions in area 18. Such area 18 connections provide more detailed analysis of the vertical components of visual objects.

Animals↗
PubMed1999

Changes in afferent impulse activity of small intestine mesenteric nerves in response to antigen challenge.

Sprague-Dawley rats (weight 130-150 g) were sensitized by an intraperitoneal injection of 1 mg chicken egg albumin with 0.25 ml Freund's adjuvant to stimulate immunoglobulin E antibody production. Leukocyte migration inhibitory factor was used as an indicator of animal sensitization. In acute electrophysiological experiments on sensitized animals, an intra-arterial or intraluminal chicken egg albumin (100 microg) challenge evoked a 10% enhancement of the activity of mesenteric nerves of the small intestine, regardless of the injection site chosen. Afferent nerve activity in control animals was not changed during the chicken egg albumin challenge. Morphometry at the light microscope level showed activation of mast cell degranulation after the antigen challenge to presensitized rats. Intraluminal injections of a stimulator of mast cell degranulation, compound 48/80 (20-30 mg), were found to increase afferent discharges in intact rats. An antagonist of H1 histamine receptors, clemastine, reduced the effect of compound 48/80. The results obtained provide direct evidence for the stimulation of sensory nerve endings by mast cell mediators released during mast cell degranulation.

Afferent Pathways↗
PubMed1999

[Structure of the interrelations between retinal neuroglia and ganglion cells].

Organization of glial environment of bodies and axons of cat retinal ganglion cells (GC) was analysed electron microscopically. Similarities and differences in types of contacts between macroglial cells and GC plasmalemma throughout its length were demonstrated. Regularities of changes of types of glia surrounding different types of GC were established. GC body was surrounded by the processes of Muller gliocytes, while a special glial crown appearing as multiple radial finger-shaped astrocyte processes covers GC initial segment. Possible functional aspects of structural organization of interrelations of GC body and axons with gliocytes are discussed.

Animals↗
PubMed1998

[Varying intensity and staining of neurons in the cat visual cortex during histochemical detection of horseradish peroxidase].

We have investigated the staining of different types of neurons after horseradish peroxidase injection in the cat striate cortex. The intensity of staining was classified as dark, intermediate, or light. Cells with different staining intensities were found in all cortical layers and at different distances from the injection site. According to the shape of their somata and the organisation of their dendritic trees, the labelled cells were identified as pyramidal, small pyramidal, non pyramidal and modified pyramidal (inverted and fusiform). The ratio of dark:light:intermediate cells within all identified morphological types was 2:1:1, except for the modified pyramidal neurons (1:1:1). Revealed peculiarity of modified pyramidal cells may serve as additional characteristic of this morphological type cells. Thus the intensity of staining depends not only on the physical uptake and transportation of enzyme but also on the organisation of axonal terminals and neuron location in the functional structure of the cortex.

Animals↗
PubMed1998

[Dependence of learning characteristics on visual object properties in Rhesus macaca by bilateral removal of the 7th field of the parietal cortex].

Removal of the rhesus monkey parietal cortex 7th field exerted no effect on learning processes involving visual discrimination of images united in their colour and geometrical form, but the learning of differentiating the spatial information did suffer. The data obtained suggests that, in the process of learning visual differentiation, spatial differentiating signs are formed, the process involving neuronal structures of the 7th field of the inferior cortex. Removal of the 7th field disrupts mechanisms of the body scheme assession and egocentric orientation resulting from visual-vestibular interrelationships.

Animals↗