Horizontal optokinetic nystagmus in the pigeon during static tilts in the frontal plane.

The influence of lateral static tilts of the body (30 degrees, 45 degrees) on horizontal optokinetic nystagmus induced by rotation of an optokinetic cylinder at a constant rate (16 degrees, 30 degrees/sec) was investigated in 16 pigeons. The experiments made it possible to identify a statistically significant tilt-dependent asymmetry of the tonic otolithic influences on the optokinetic system which consisted in a marked inhibitory effect on horizontal optokinetic nystagmus of right-sided tilts by contrast with left-sided. The separate recording of oculomotor responses of the right and left eyes showed that the temporonasal-nasotemporal (TN-NT) asymmetry of horizontal optokinetic nystagmus which exists in the norm in the pigeon is maintained under the conditions of stationary lateral tilts of the body for the eye which is in the upper position, and is replaced by a symmetrical pattern for the eye which is in the lower position. The results make it possible to hold the view that the mechanism of TN-NT asymmetry is controlled by otolithic inputs, and that its function may be substantially modified under the influence of the reorientation of the otolithic membranes in the gravitational field.

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

The influences of the static whole body roll tilts (30 or 45 degrees) on horizontal optokinetic nystagmus (HOKN) produced by optokinetic stimuli at a constant velocity (16 or 30 degrees/sec) were examined in the 16 pigeons. The significant tilt-dependent asymmetry of the tonic otolith effects on optokinetic system was revealed which consists in pronounced inhibitory effect of the right-hand tilts unlike the left-hand tilts on HOKN. Separate recording of the oculomotor responses from the right and left eyes showed that during static roll tilts the temporonasal-nasotemporal (TN-NT) asymmetry of HOKN normally existing in the pigeon remained for the eye disposed above and was replaced by symmetric pattern for the eye disposed below. The results suggest the mechanism of TN-NT asymmetry is controlled by the otolith inputs and its function can be essentially modified under the influence of otolith membranes reorientation in gravity.

[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.

[Features of the formation of the cortical "kindling" phenomenon in acute experiments on cats]. / Issledovanie osobennostei formirovaniia korkovogo fenomena "raskachki" v usloviiakh ostrogo opyta na koshkakh.

The possibility of cortical "kindling" organization in short time interval (2-3 hours) was shown in acute experiment on cats. The middle area of g. suprasilvius was stimulated by square current pulses (20 per s, 1 ms duration for 5 s with interstimulus intervals of 3 min). As a result of stimulation after the projection discharge in the mirror focus the convulsive activity generalization and formation of independent secondary focuses were observed. In the process of formation of cortical "kindling" the activity of spindle waves could be recorded in all ECoG traces. The frequency of spindle emergence grew according to the epileptization of the animal. The spindle activity transformation into the multiple spike-wave activity was also recorded. The results obtained proved the participation of subcortical structures in the formation of cortical "kindling".