[Morphometric analysis of the motor analyzer structures in albino and gray rats]. / Morfometricheskii analiz struktur dvigatel'nogo analizatora u belykh i serykh krys.

Cellular content of neuron populations of cortex, subcortical structures of brain and cerebellum and nuclei of anterior horns of cervical region of the spinal cord was studied in albino and grey rats. The revealed distinctive features of the tinctorial properties and sizes of neurons of different structures of the motor analyser are explained as an adaptation peculiarities of the animal brain organization. Heterogeneity of neuron population at different levels of the brain motor system indicates the different adaptation mechanisms of albino and grey rats.

On the specificity of neurons and visual areas.

The dominant view during the past 40 years has been that the visual system analyzes the visual scene by breaking it down into basic attributes such as color, form, motion, depth and texture. Individual dedicated neurons and specific visual areas were believed to be devoted to the analysis of each of these attributes. Current research has challenged these views by emphasizing that neurons, especially in the cortex, have multifunctional properties and therefore serve as general-purpose analyzers rather than feature detectors. Consequently, it appears that most extrastriate visual areas, rather than each being devoted to the analysis of a specific basic visual attribute, perform several different tasks and thereby engage in more advanced and complex analyses than had been realized.

Functional streams in occipito-frontal connections in the monkey.

It is known that the prestriate cortical regions that project to area LIP in parietal cortex and to areas TEO and TE in temporal cortex are mostly separated. Two separate streams of information transfer from occipital cortex can this be distinguished. We wished to determine whether the parietal and temporal streams remain segregated in their projections to frontal cortex. Paired injections of retrograde fluorescent tracers were placed in parietal and temporal cortex, or in the lateral and medial parts of the frontal eye field (FEF). The cortical regions containing retrogradely labeled cells were reconstructed in two-dimensional maps. The results show that temporal cortex mainly projects to lateral FEF (area 45). Parietal cortex sends projections to medial FEF (area 8a) and to lateral FEF, as well as to area 46. Thus, the parietal and temporal streams converge in lateral FEF. Most of the occipital regions projecting to medial FEF are the same as those projecting to parietal cortex, whereas lateral FEF receives afferents from the same occipital regions as those sending projections to temporal cortex. Thus, one can distinguish two interconnected networks. One is associated with the inferotemporal cortex and includes areas of the ventral bank and fundus of the superior temporal sulcus (STS), lateral FEF and ventral prestriate cortex. This network emphasizes central vision, small accades and form recognition. The other network is linked to cortex of the intraparietal sulcus. It consists of areas of the upper bank and fundus of STS, medial FEF and dorsal prestriate cortex. These areas encode peripheral visual field and are active during large saccades.

Development and experience lead to increased volume of subcompartments of the honeybee mushroom body.

The mushroom bodies of insects are believed to be involved in higher order sensory integration and learning. In the honeybee, the mushroom body can be separated into three different, modality-specific input compartments and several morphologically inseparable output regions. By means of morphometric analysis we show that the volumes of these subcompartments depend on both the age of the adult bee and its experience. For the most part a significant, age-dependent increase in neuropile volume is observed. Additionally, the olfactory and visual input regions show experience-related differences. Unlike other subcompartments, the visual input region does not change in volume with age, but only with experience. We thus suggest that experience is an important factor in the structural development of higher order brain regions of an insect, the honeybee.

[Connections between area AIV and areas AI, AII and Ep of the auditory cortex in the cat]. / Sviazi zony AIV s zonami AI, AII i Ep slukhovoi kory bol'shogo mozga koshki.

Zones AI A11 and Ep in the cat auditory corex have been studied layer-by-layer electron microscopically after the zone AIV has been removed. Terminals having degeneration signs according to the dark type are mainly found in the layers V-VI of all the auditory cortex zones studied. Additional degenerative zones are revealed in the layer I of the zone AII and in the layer II of the zone Ep. Not any additional foci of degeneration are found in the zone AI. A suggestion is made concerning a physiological significance of the afferent distribution in the connective systems investigated. The corticocortical connections are formed by axodendritic and axospine synapses.

[Retino-pulvinar pathway of the cat brain]. / Retino-pul'vinarnyi put' golovnogo mozga koshki.

Peculiarities on axonal distribution and termination of the retinal ganglionar cells within the limits of the thalamic pulvinar nuclei have been studied in 10 cats by means of the radioautography method combined with silver nitrate impregnation (Fink--Heimer technique). The ganglionar cells have projections on two pulvinar nuclei -- the lateral and the inferior. The medial pulvinar nucleus has no similar connections. The retinal projections in the pulvinar nuclear complex are bilateral and nearly symmetrical, the contralateral projections of the pathway somewhat predominate.

Correlation between the morpho-functional organization of some portions of the visual analyser of chelonia and their ecology: I. Normal morpho-functional characteristics of the optic nerve and the tectum opticum.

Several methods (light optic, electron microscope and electrophysiological) were used to study the optic nerve and the tectum opticum of water turtles (two species) and of land tortoises (two species). As the result of study of the two levels of the visual analyser in four species of Chelonia three groups of signs of the morpho-functional organization were distinguished: signs common for the Chelonia under study; ecologically specific signs--common for water turtles and species-specific traits which are--different in species of the same ecological group. Specific features of structural-functional organization of the visually directed behaviour in Chelonia at the neuronal populations level were shown to correlate with the ecological features to a greater degree than with the systematic position of the species.

Correlations between the morpho-functional organization of some parts of visual analyzer and ecology in Chelonia: II. Morpho-functional characteristics of the visual nerve and tectum after unilateral enucleation.

The morpho-functional characteristics of the optic nerve and tectum opticum were studied electronmicroscopically and electrophysiologically after unilateral enucleation in 4 Chelonia species. Different types of degeneration of the myelinated and unmyelinated optic fibers and their endings in the tectum are revealed. Comparison of the types and times of the degeneration of retinal axons and their terminals with changes of the tectum evoked potentials at different times after enucleation gives ground to conclude that myelinated fibers produce nerve endings degenerating on the dark pattern and unmyelinated, all the remaining endings with the light, neurofilamentous, glycogenous, vesicular and other degeneration patterns. A stratal arrangement of the retino-tectal projections of various type fibers is demonstrated. Asynchrony of the process of degeneration of different groups of fibers and the relationship between the rate of degeneration and the diameter of myelinated fibers, as well as the absence of a relationship between the change pattern and the diameters of myelinated and unmyelinated axons are revealed. In land tortoises and water turtles differences are revealed in the set of major degeneration patterns and their endings also in the patterns of stratal distribution of various categories of the retinal fibers and tectum. A possible relationship is proposed between the above differences and ecological properties of the Chelonia groups under study. Also revealed are species-specific features of some substantial aspects of the morpho-functional organization of the levels of the visual analyzer in Chelonia.

[Indices of the structural organization of various cortical formations in the left and right human cerebral hemispheres]. / Pokazateli strukturnoi organizatsii nekotorykh korkovykh formatisii v levom i pravom polushariiakh mozga cheloveka.

Some characteristics of the structure of locomotor fields 44 and 45, and of the cortical fields 4 and 6 of the motor analyzer in the left and the right hemispheres of the human brain were studied. The study revealed statistically significant differences between some of the characteristics. The index of the vertical arrangement of the pyramidal neurons in layer III of fields 44 and 45, as well as field 6 were greater in the left hemisphere than in the right one. The size of the profile field of Betz's cells in field 4, and of the large pyramidal neurons in layer III of field 6 were greater also in the left hemisphere in two brains out of 4, and showed no differences in the other 2. The size of the profile fields of the pyramidal neurons in layer III of fields 44 and 45 was much greater in the left hemisphere in all the cases.

[Associative connections of the parietal region of the cerebral cortex in cats]. / Assotsiativnye sviazi temennoi oblasti kory golovnogo mozga koshki.

The interneuronal connections of the parietal associative cortex were studied in cat using the methods of retrograde axonal transport of horseradish peroxidase (HRP) and terminal degeneration (Fink-Heimer). Data on laminar topography of the afferents within area 7, and the nature of axonal terminals from visual, auditory and somatic sensory fields of cortex were obtained. The places of concentration of associative neurons and their morphological characteristic are described.