[Morphofunctional characteristic of the rat distal spinal cord after its complete experimental section with subsequent treadbun training of the animal].

Motor activity of rats has been studied after complete experimental section of spinal cord at the lower thoracic level. A treadbun training performed one day after the operation has been shown to lead to the appearance of movement of hindlimbs and to restoration of function of support of the body weight. In our opinion, the key moment in initiation of locomotor movements is stimulation of foot. Morphoimmunohistochemical study (detection of nuclear protein of proliferation cells, synaptophysin, and glial fibrillary acid protein) of the lumbar enlargement has allowed revealing reorganization of motoneurons, interneurons, and afferent chain in the distal part of the sectioned spinal cord. In trained animals there are observed the normal structure of motoneurons and the appearance of aggregates of synaptophysin-immunoreactive structures lost after the operation.

[Relation between the spatial characteristics of the receptive fields of the superior colliculi of the cat and the rate of movement of a photic stimulus]. / Zavisimost' prostranstvennykh kharakteristik retseptivnykh polei perednikh bugrov chetverokholmiia koshki ot skorosti dvizheniia svetovogo stimula.

The receptive fields of visual cells in superficial and intermediate layers of the cat superior colliculus were investigated: their boundaries, size, shape, dependence on the velocity of stimulus. The size of the excitatory zone decreased whereas the firing rate of the cells increased when the velocity 3 +/- 180 degrees.S-1 was changed. That was typical of both directionally and non-directionally selective cells. The mechanism of directional selectivity is discussed.

Eye movements in the cat evoked by electrical stimulation of the outer geniculate body.

New data were obtained in experiments with unanesthetized animals showing that electrical stimulation of the structures of the outer geniculate body of the cat elicits goal-directed eye movements. Relationships were found between eye-movement amplitude and direction and the position of the eye at the instant of stimulation, as well as the position of the stimulating electrodes in the outer geniculate body. A scheme is proposed for the multilevel interaction of the visual and oculomotor systems during their functioning, and a possible relation is discussed between the described phenomenon and the mechanisms responsible for the foveation of objects during their recognition.

[Directional selectivity of the neurons of the superior colliculi in the cat: the effect of the rate of movement of a stimulus]. / Direktsional'naia izbiratel'nost' neironov perednikh bugrov chetverokholmiia koshki: vliianie skorosti dvizheniia stimula.

Responses to stimuli moving with velocities of 3-180 degrees X sec-1 were studied in each of four axes (eight directions) separated by 45 degrees in neurons of the cat superior colliculus. 69% of units were directionally selective. In 55% of all the neurons the directional selectivity depended on stimulus velocity and was the largest for high velocities (over 10-30 degrees X sec-1). The preferred direction for some neurons was reversed with velocity increasing. The directional selectivity-velocity relationships were compared for the cat superior colliculus and visual cortex and discussed in regard to probable role of this phenomenon in the oculomotor system.

[Model of mechanisms forming reactions of cat's lateral geniculate nucleus neurons to moving stimuli]. / Model' mekhanizmov formirovaniia reaktsii neironov naruzhnogo kolenchatogo tela koshki na dvizhushchiesia stimuly.

The neurons net with a space-time negative feedback is described by the integral equations system. Solution of the system is made numerically. Mechanisms of LGN neurons reaction (for the cat) are investigated by means of such model. The model and experimental results are compared.

[Response of lateral geniculate body neurons to moving light bands in cats]. / Issledovanie otvetov neironov naruzhnogo kolenchatogo tela koshki na dvizhushchiesia svetlye polosy.

A number of electrophysiological investigations revealed that the relief of activity (RA) arising in outputs of overlapping receptive fields (RFs) of the LGB reflects the form of test image. The RA was reconstructed by the responses of single neurons. The bars' width and velocity of their movement varied. Dependence of RA size on the image size was approximated with the aid of the logarithmic function for the small angle images (less than 1.5 +/- 2.0 angle degrees) and of the power function for larger sizes. The interrelationships obtained take place within the scope of motion rates from 0.6 to 30 angle degrees per second. This scope of motion depends on the eccentricity of RFs centers in respect to the area centralis.

[Convergence of activating connections of retinal on- and off-ganglion cells on lateral geniculate body neurons]. / O konvergentsii vozbuzhdaiushchikh sviazei on- i off-gangliozonykh kletok setchatki s neironami naruzhnogo kolenchatogo tela.

On- (off-) central neurons of the retina and lateral geniculate body (LGB) generate off- (on-) responses to stimuli acting upon the periphery of their receptive fields (RFs). We have found neurons with equal on- and off-responses to testing of the central part of their RFs. RFs of such neurons consist of overlapping on- and off-areas. The type of their responses can change on alteration of the stimulus parameters or under influence of light adaptation. A number of the LGB neurons seem to have activating inputs both from on- and off-central ganglionic cells of retina.