Unlabelled: Studying compensatory capacity of the brain is a pressing issue. To resolve it, diversified experiments should be conducted providing an idea of the underlying mechanisms and possibilities of functional restoration.
Aim: To determine the effect of unilateral electrocoagulation of supraoptic (SO) and suprachiasmatic (SCH) hypothalamic nuclei on the appearance of the electroretinogram (ERG).
The study of visual cortex local changes caused by strychnine and potassium chloride revealed significant changes (relief or depression) not of evoked potentials in the cortex only, but of unidirectional changes of the total electroretinogram (ERG) amplitude and its components as well (early receptor and oscillator retinal potentials). Cortex excitability decrease or increase resulted in inhibition or facilitation of early receptor potential development respectively due to weakening or strengthening of the inhibitory neurotransmitter GABA effect in photoreceptor synapses. Changes of ERG components and retinal oscillator potential corresponded to the changes of visual evoked potentials that reflected upon cortex inhibition or facilitation.
View Article and Find Full Text PDFGeorgian Med News
October 2011
The aim of the study was to reveal endoscopic changes of a bronchial tree in patients with sarcoidosis of respiratory organs with apply endobronchial microsurgical biopsy interventions. Under our supervision there were 57 patients with various forms intrathoracic sarcoidosis. The character of endobronchial displays of disease and changes of mucous bronchial tubes are depicted.
View Article and Find Full Text PDFNeurophysiological processes of transduction and analysis of information concerning brightness of photostimuli and peculiarities of functioning of visual system under exposure to extra-bright light effects or extreme contrasting of visual objects are studied poorly and present significant interest for unraveling actual mechanisms of visual perception under extreme conditions. Conducting analysis of visual system in maximal broad range both in terms of adequate perception and reflection of light stimulus intensity and adaptive mechanisms to extra-strong illumination regimes is as well very important. The to-date obtained data indicate that under the extreme light effects pathology of the peripheral portion of visual analysator can be induced.
View Article and Find Full Text PDFThe article presents the results of serological investigation for presence of specific markers of hepatitis B (HBV) and hepatitis C (HCV) infections in serum samples obtained from 600 patients with acute and chronic forms of lung tuberculosis (LT) and in control group I - 600 healthy adults and in control group II - 796 patients with somatic pathology from multiprofile hospital. It has been established that among LT patients frequency of revealing HBsAg and anti-HCV is statistically steady; similar indicators are among persons from both control groups. The frequency of revealing of these markers among patients with chronic forms of LT is considerably higher than frequency of their revealing in patients with acute forms of LT.
View Article and Find Full Text PDFVestn Oftalmol
September 2009
Pigment retinal dystrophy induced by the administration of monoiodacetic acid was characterized by a unilateral inhibition of parameters of all components of not only electroretinography, but also evoked potentials of the visual cortex and superior colliculus: higher thresholds of their formation relatively to the controls, and displacement of saturation areas towards low intensities. Correlations of retinogeniculocortical and retinocolliculocortical pathways of visal information transmission were ascertained to be an important factor in the mechanism of visual analyzer functioning in certain abnormalities.
View Article and Find Full Text PDFRoss Fiziol Zh Im I M Sechenova
May 2003
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.
View Article and Find Full Text PDFChronic 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.
View Article and Find Full Text PDFRoss Fiziol Zh Im I M Sechenova
April 1997
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.
View Article and Find Full Text PDFStimulation 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.
View Article and Find Full Text PDFFiziol Zh SSSR Im I M Sechenova
November 1992
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.
View Article and Find Full Text PDFNeurosci Behav Physiol
April 1992
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.
View Article and Find Full Text PDFFiziol Zh SSSR Im I M Sechenova
August 1990
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.
View Article and Find Full Text PDFZh Vyssh Nerv Deiat Im I P Pavlova
December 1989
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.
View Article and Find Full Text PDFNeurosci Behav Physiol
March 1986
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.
View Article and Find Full Text PDFERG 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.
View Article and Find Full Text PDFThe effect of different inorganic and organic selenium compounds on the nucleic acid synthesis in culture of human carcinoma ovary cells was studied. The rate of synthesis was determined by the incorporation of 3H-thymidine in the DNA and 3H-uridine in the RNA. Selenium compounds in the concentration to 1 mg/ml inhibited the nucleic acid synthesis in human tumour cells.
View Article and Find Full Text PDFFiziol Zh SSSR Im I M Sechenova
June 1983
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.
View Article and Find Full Text PDFFiziol Zh SSSR Im I M Sechenova
December 1977
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.
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