[Selective predation on tadpoles of three tailless anuran species].

In laboratory experiments an introduced fish Perccottus glenii consumed selectively tadpoles of three numerous anuran amphibian species of Moscow Province. Perccottus glenii actively consumed all seized tadpoles of the Rana arvalis and R. temporaria.

[Bilateral intracentral interaction in the olfactory system of teleost fish in the guppy Poecilia reticulata Peters].

The bilateral interaction was studied in the olfactory system of the bony fish guppy by means of olfactory conditioning to the synthetic odorant beta-phenylethanol with one or both the olfactory organs functioning. Monorhinal conditioned reflex was revealed by beta-phenylethanol action on the receptors of the second olfactory organ which had not been functioning in the course of conditioning (the phenomenon of lateral transfer). The birhinal conditioned reflex persisted for 75 days while monorhinal conditioned reflex revealed no such duration.

[Recognition of chemical stimuli by guppy, Poecilia reticulata Peters].

An alimentary conditioned reflex to beta-phenylethanol and a subsequent differentiation of cumarine were elaborated in conditions of simultaneous paired choice in guppies. It was shown that beta-phenylethanol in a concentration not over 7 X 10(-6) M is perceived through olfaction. The conditioned reflex persists for a long time: twenty five to fifty days after section of the olfactory nerves (the conditioned reflex is restored after their regeneration) and at least seventy days in intact fishes.

[Role of retinal projections to the rostral thalamus in the perception of stationary objects in frogs].

The round of stationary obstacles demanding localizing and definition of objects, was restored within 12--17 days after cutting of both optic nerves in Rana temporaria. Electrophysiological data indicated the restoration of connection between the retina and rostral thalamic nuclei by this time. The on-type impulse reactions to light stimuli in retinal ganglionic cell endings were observed.

[Distribution of myelinated fibers in the outer plexiform layer of the optic tectum in the frog, Rana temporaria].

Distribution of myelinated nervous fibers in the layer 9 of the optic tectum of the frog Rana temporaria has been investigated in normal animals as well as 6--9, 60 and 134 days after contralateral enucleation. Counts were made on long and oriented sections at the screen of electron microscope. Fields of myelinated fibers in the layer 9, visible under light microscopic, are not distinguished by higher density of these fibers and differ from the other parts of sections probably due to some qualitative differences, especially because of parallel orientation of these fibers within a field.

[The neuronal reactions of the nucleus isthmi area in the frog rana temporaria to visual stimuli].

Studies have been made on the neuronal reactions in the isthmic nucleus area of the frog to visual moving stimuli and to changes in total illumination. Visually activated neurons of this area are characterized by large receptive fields (located only in the visual field of contralateral eye), intensive reactions to diffuse illumination, high sensitivity to moving contrast targets (especially large ones) and evident adaptation. Approximately 23% of the neurons exhibited directional sensitivity, mainly to targets moving in temporo-nasal direction.

[Laminar analysis of the synaptic organization of the frog optic tectum].

Distribution of axo-axonic and axo-dendritic synapses, nervous terminals and neuron somata in the depth of the optic tectum was studied in frog Rana temporaria L. in norm and 6-9, 60 and 134 days after contralateral eye enucleation. In outer plexiform layer 9 density of synapses was found to be maximal near the surface of the tectum; it decreased in deeper levels.

[Responses of neurons in the nucleus isthmi region of the frog to optic nerve stimulation].

Neuronal responses were studied in the nucleus isthmi area of Rana temporaria. The animals were immobilized by diplacine, a curare-like drug. Single neurons in this area had no background activity.

[Restoration of the behavioral reactions of Rana esculenta frogs during regeneration of visual nerve fibers].

After sectioning the optic nerve, various forms of visually guided behaviour in the frog R. esculenta recover unevenly. Within 16--20 days, the onset of reactions was observed which are associated with perception of relatively large unmoving objects during active locomotion of animals (1); within 55 days -- avoidance reactions (2); within 90 days -- feeling reactions (3) were formed.

[Axonal composition of the marginal and basal optic tracts of the grass frog].

An electron-microscopy study of the marginal optic tracts (the medial and lateral divisions) and basal optic tract was performed for the frog Rana temporaria. The resemblance between the ultrastructure and composition of the marginal tracts is revealed. The basal tract is characterized by a relatively loose structure and considerable content of the myelinated large diameter fibres.