Biomedical subjects

N M Rzaeva

Publications and source records attributed to N M Rzaeva.

12 recordsLinked to original sources

PubMed2003

[Neurophysiological study of short-latency potentials in central structures of visual system and their relations to additional oscillations in retina].

In chronic experiments on alert rabbits, the formation of short-latency positive and negative potentials preceding initial responses, in wide range of light intensities in visual structures, were revealed. The observed potentials were registered in retina under light intensity of 100-120 J. In corpus geniculatum laterale, colliculus superior and visual cortex, they were initiated under 30 J, 15-50 J and 50 J, respectively. The relations of these potentials to light stimulus intensities were studied.

Animals↗

PubMed1997

[The role of the central nervous system functional condition in formation of responses of visual analyser's peripheral and central parts].

Nembutal was shown to inhibit formation of early receptor potentials, "a"-wave and oscillatory potential of the retina (ERG), as well as the oscillatory potentials of the superior colliculus and visual cortex. The first oscillatory potential of the retina alone was enhanced. Aminazin exerted rather an opposite effect related, probably, to facilitation of the retina and central structures due to elimination of a constant inhibitory effect of the brain stem RF.

Animals↗

PubMed1995

[The effect of stimulation of the suprachiasmatic and supraoptic nuclei of the anterior hypothalamus on the evoked activity of the visual cortex in rabbits].

Stimulation of the hypothalamus' suprachiasmatic (SCH) and supraoptic (SO) nuclei induced short-latency hypothalamo-cortical responses in the visual cortex affecting the light-induced responses. Possible mechanisms of the differential effects of the stimulation upon different phases of the visual EPs, and participation of the RF in these mechanisms, are discussed. There seems to exist an interconnection between the hypothalamic and light stimuli in the visual cortex.

Animals↗

PubMed1992

[The influence of the anterior hypothalamus on the electrical activity of the retina].

Single stimuli applied to the suprachiasmatic and supraoptic nuclei of the hypothalamus evoked short-latency hypothalamo-retinal responses which exert influences upon formation of the "a" and "b" waves of the electroretinogram, the changes of the waves being opposite by character. The effects from the suprachiasmatic and supraoptic levels were opposite, too.

Animals↗

PubMed1990

[The influence of the posterior hypothalamus on the visual cortex in different states of the reticular formation].

In alert rabbits, stimulation of posterior hypothalamus induced short-latency responses in the visual cortex and affected the formation of the EPs to light. Depending on the intervals between the stimuli, either initial extinction of the EPs (1-15 msec) or subsequent selective facilitation of its positive component with simultaneous depression of negative (20-100 msec) one, or complete recovery of the response (200-300 msec), were observed. Aminazine and benactizine made the effect of the posterior hypothalamic stimulation on visual EPs to light less obvious and changed its dynamics. Other findings suggested an inhibitory effect of the mesencephalic RF on the activity of hypothalamo-cortical input. A role of phasic mechanism of hypothalamic control in realization of visual cortex's perceptive function, is discussed.

Animals↗

PubMed1985

[Oscillatory evoked potentials in the rabbit visual system during experimental retinal pathology induced by administration of monoiodoacetic acid].

ERG and EP of the visual cortex (VC) and superior colliculus (SC) were investigated under experimental dystrophy of the retina induced by intravenous injection of monoiodoacetic acid in different doses. The relative resistance of the VC to the derangement of retinal function was established. It was manifested by less marked suppression of its EP as compared with ERG. Taking into consideration the selective projection to the SC of the rod system that was damaged to a greater degree under pathology in question, it is suggested that functional suppression of the SC might facilitate the conduction of visual information through the main retino-geniculo-cortical canal. This might be one of the factors of VC resistance to the impairment of retinal function. This assumption was confirmed in experiments with SC electrocoagulation in which one could observe the facilitation of EP formation of the contralateral VC.

Animals↗

PubMed1983

[Relation of short-latency processes in the visual system of the rabbit to pre-excitation inhibition in the retina].

Low-amplitude early negative potential preceding the positive component of primary responses to light was observed in the optic tract, superior colliculus, lateral geniculate body and visual cortex in chronic experiments with special recording schedule in rabbits. The early negative potential proved to be genetically connected with the "a"-wave of the electroretinogram. During the suppression of all but the "a"-wave ERG components with glycine, the early negative potential alone is preserved in the central structures of the visual system.

Action Potentials↗

PubMed1977

[Oscillatory potentials in the structures of the visual system].

The electroretinogram oscillatory potentials have similar general configuration and frequencies. Under the conditions of experimental dystropia of the retina and also after glycine administration, suppression of the oscillatory potentials formation in retina is accompanied by suppression of the evoked responses formation in the LGB, superior colliculi, visual cortex, and chiasma. The oscillatory potentials in the cerebral structures are related to the primary complex of their evoked responses. The importance of using the oscillatory potentials to study the mechanism of influence of the visual stimuli on the evoked potentials, is discussed.

Animals↗

PubMedDate not supplied

Association of short-latent processes in the rabbit visual system with pre-excitation inhibition in the retina.

An electrographic correlate of short-latent processes in the visual system corresponding to the ERG a-wave was detected in chronic experiments on awake rabbits. The formation of an early negative potential (ENP), small in amplitude, that precedes the positive component of the primary responses (PR) to light and is thus the earliest signal concerning the arrival of information from the retina was detected during a special recording regimen in the optic tract, superior colliculi, outer geniculate body, and visual cortex. The shift in the latent periods with respect to the onset of the development of the ERG a-wave comprised 2-3 msec in all the above structures. The suppression of all ERG components except the a-wave by glycine injected into the vitreous body was accompanied in all structures by the suppression of all PR components except the very initial ENR. Since the pre-excitatory inhibition of ganglionic elements corresponds to the ERG a-wave at the exit from the retina, the role of this inhibition in the transmission of information concerning the very first instant of the visual signal both to subcortical centers and the visual region of the cerebral cortex should be recognized.

Animals↗

PubMedDate not supplied

Influence of the posterior hypothalamus on the visual cortex in various states of the reticular formation.

It has been demonstrated in chronic experiments on wakeful rabbits that the stimulation of the posterior hypothalamus by a single electrical stimulus leads to the formation in the visual cortex of a short-latency response which exerts a substantial influence on the formation of the reaction to light stimulation. Depending upon the intervals between the hypothalamic and light stimuli, an initial suppression of the response is observed (1-15 msec), a subsequent selective facilitation of its positive component in the presence of the simultaneous suppression of the negative (20-100 msec), and the complete recovery of the response (200-300 msec). Aminazine and amizil do not alter the directionality of the influence of the stimulation of the posterior hypothalamus on the responses of the visual cortex; however, they do significantly attenuate the degree of expressivity and the dynamics of this influence. Experiments involving local foci in the mesencephalic reticular formation (strychnine, KCl) attest to the inhibitory influence of the latter on the activity of the hypothalamocortical input. The role of the phasic mechanism of hypothalamic control in the realization of the perceptual function of the visual cortex is considered.

Animals↗

PubMedDate not supplied

Role of the functional state of the central nervous system in the mechanism forming responses from the peripheral and central parts of the visual analyzer.

Chronic experiments on rabbits showed that changes in the functional state of the central nervous system induced by Nembutal and changes in the brainstem reticular formation induced by aminazine had significant effects on the formation of the early receptor potential, a-wave, and oscillatory potentials of retinal ERG signals, as well as on oscillatory potentials in the superior colliculi and visual cortex. Nembutal inhibited the formation of the early receptor potential, the a-wave, and the second and third ERG oscillatory potentials, and had similar effects on the oscillatory potentials of the superior colliculi and the visual cortex. Only the first oscillatory potential was enhanced in all visual system structures. Aminazine had long-lasting enhancing effects on the formation of the early receptor potential and the a-wave and on the oscillatory potentials of the retina, superior colliculi, and visual cortex. This enhancement may be associated with "release" of the retina and central structures from the constant inhibitory influences of the brainstem reticular formation.

Animals↗

PubMedDate not supplied

[The functional connections of the supraoptic and suprachiasmatic nuclei of the anterior hypothalamus with the superior colliculi].

Interrelation of single hypothalamic (supraoptic--SO and suprachiasmatic--SCH nuclei) and light stimuli at the level of superior colliculus (SC) were studied during chronic experiments in waking rabbits. Short-term inhibitory and the subsequent facilitatory effects of the hypothalamic stimuli on SC responses induced by light flashes were established. The foregoing light stimulus caused inhibitory effect on formation of hypothalamo-collicular responses induced by SO and SCH nuclei stimulation. The final result of the anterior hypothalamic effect on SC function is the vector value of the mechanism of interrelation between the hypothalamic inputs in this structure.

Animals↗