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Biomedical subjects

G D Kuznetsova

Publications and source records attributed to G D Kuznetsova.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

The dynamic of thermal fields of the brain of rats in the late post-resuscitation period under stress.

The temperature topography of the cerebral cortex of rats following clinical death and resuscitation was investigated with the technique of thermoencephaloscopy. Complete restoration of the neurological status of the animals was achieved over the course of one to two days. Marked disturbances in the background thermal maps and the thermal reactions of the cerebral hemispheres induced by a stressor were identified in the remote post-resuscitation period (up to two months). A pathological mosaicism of the thermal characteristics was detected under the conditions of relative rest, as were disturbances in the dynamics of the temperature reactions of the brain and in the character of the interhemispheric asymmetries under stress. The individual character of the post-resuscitation pathology which is found both in the baseline thermal maps as well as following a functional load is emphasized. The results of the investigation point to the importance of an individual approach in the rehabilitation therapy of the post-resuscitation illness.

Animals↗
PubMedDate not supplied

Temperature reactions of the rat cerebral cortex and distant effects of an experimentally induced excitatory focus.

The method of dynamic thermovision was used in white rats to investigate the distant reactions of the cerebral cortex arising during local chemical perturbation (2% KC1). In addition to the earlier-described temperature wave of propagating depression (T waves), local areas of warming (by 0.2-0.3 degrees) symmetrical to the site of stimulation were found in the opposite hemisphere. Latent excitation foci during local chemical action were found on the dynamic thermal maps of the brain surface in regions remote from the stimulation site in the same or contralateral hemisphere. A change in the site of T-wave origination and the typical sequence of its propagation through the cortex could be observed when two potassium foci were created, as well as the development of foci of prolonged temperature oscillations at the site of encounter of two T waves. On the basis of the obtained data several questions are discussed concerning the forms and mechanisms of distant effects in the CNS.

Animals↗
PubMedDate not supplied

[Possible mechanisms for forming typological features of behavior of WAG/Rij line rats].

Typological behavior reactions of WAG/Rij rats were studied from the standpoint of divergent modulatory integration hypothesis. This rat strain has a genetically determined dominant dysfunction of the benzodiazepine system of the thalamic nuclei. This disorder provokes an epileptiform disease such as absence epilepsy. It was suggested that the dysfunction of this system would result in a modification of the modulatory systems, which support the motivation states of escape and avoidance reactions as well as of the modulatory systems, which form the emotional states. Modifications of these states are the background of typological behavioral features of WAG/Rij rats. It was shown that WAG/Rij have the lower threshold of the development of haloperidol catalepsy, higher levels of fear and depression. On the first day of training in a shuttle box, WAG/Rij rats demonstrated better avoidance performance than Wistar rats. On the second and 28th days, the amnestic effect of the epileptiform disease was observed. The amnestic effect was also observed after passive avoidance conditioning. The results are discussed in terms of the modulatory integratin hypothesis.

Animals↗
PubMedDate not supplied

[The interhemispheric brain asymmetry of the rabbit in a state of "animal hypnosis"].

By the method of forced immobilization the rabbits were brought into the state of "animal hypnosis" (immobilization reflex), and their ECoG was recorded, which was further processed on the computer. It was found that during hypnosis a functional interhemispheric brain asymmetry was developed in rabbits with activity predominance in the right hemisphere. The "animal hypnosis" is a phasic process: in the ECoG of the rabbit under hypnosis a regular alternation of delta and theta activity takes place. Electrophysiological reconstructions in the rabbit brain during the change of its functional state correlate with the brain thermal reactions, revealed earlier.

Animals↗
PubMedDate not supplied

[The dynamics of the brain heat fields of rats in the late postresuscitation period during stress].

By thermoencephaloscopy method the temperature relief of the rats cerebral cortex was studied after the clinical death and reanimation. The rehabilitation of the animals neurological status was completed in 1-2 days. In the remote postresuscitation period (up to 2 months), expressed disturbances were revealed of the background thermomaps and of thermal reactions of the cerebral hemispheres, evoked by the stress influence. Pathologic mosaics of thermal characteristics was revealed in conditions of relative rest and disturbance of dynamics of the brain temperature reactions and the character of interhemispheric asymmetries at stress influence. Individual character is pointed out of postreanimative pathology, which is manifest both in the background thermomaps and after the functional load. The results of the studies suggest the importance of individual approach in rehabilitation therapy of postreanimative disease.

Animals↗
PubMedDate not supplied

[Post-radiation effect on the interhemispheric asymmetry in EEG and thermography characteristics].

Complex analysis of EEG and thermographic parameters carried out in 10 healthy subjects and 34 patients, Chernobyl clean-up participants revealed a correlation between EEG and brain temperature changes in the baseline state and during mental arithmetic. During cognitive activity the maximal increase in the average EEG coherence and temperature shifts in healthy subjects were observed in the left frontotemporal and right parietotemporal areas. In patients changes in both parameters under study were most pronounced, the interhemispheric relations were impaired. The visual analysis revealed "flat" and "hypersynchronous" EEG types in patients. The dominant pathologic activity in the betal range indicative of mediobasal and oral brainstem lesions was characteristic of the flat EEG. This type of activity was observed in 60% of patients. In these cases, a general decrease in EEG coherence and temperature was most pronounced in the left hemisphere. The hypersynchronou EEG type (40% patients) was characterized by paroxysmal activity in the theta and alpha ranges suggesting diencephalic brain lesions. In these cases, EEG coherence and temperature were more variable; changes in the right hemisphere were significant, be it increase or decrease. Our complex approach to investigation of brain activity in different aspects seems to be promising in estimation of the brain functional state both in healthy persons and patients in remote terms after exposure to radiation. The specific hemispheric temperature changes revealed in Chernobyl patients especially during cognitive activity can be the sequels of postradiation disorders of vascular neuro-circulation. The EEG findings suggest subcortical disorders at different levels (diencephalic or brainstem) and functional failure of the right or left hemispheres in remote terms after exposure to radiation.

Brain↗
PubMedDate not supplied

[The influence of neonatal ketamine injection on pain sensitivity and audiogenic seizures in adult rats].

The remote effects of neonatal (on the 3d-to-9th postnatal days) ketamine injections (10 and 50 mg/kg in 20 microliters of distilled water, s.c.) were analyzed in adult Wistar, WAG/Rij, and KM (a strain with high audiogenic sensitivity) rats. Both ketamine and water injections increased pain sensitivity in adult rats. Neonatally injected water increased the mean score of seizures in Wistar and WAG/Rij, whereas ketamine water solution injected in the dose of 50 mg/kg did not change the seizure intensity (as compared to the intact control). Consequently, ketamine significantly reduced the mean score of the audiogenic seizure fit without change in its latency. In highly sensitive KM rats the neonatally injected ketamine (50 mg/kg) significantly shortened the mean latency of the fit onset, and fit stages developed faster. Thus, the neonatal ketamine injection increased the audiogenic seizure susceptibility of brain structures in KM rats.

Acoustic Stimulation↗
PubMedDate not supplied

[Temporal sequence of SWD emergence and spontaneous jerks in WAG/Rij rats with absence epilepsy].

In rat model of absence epilepsy, abnormal complex movements of cervicothorathic part (jerks) were observed in the state of passive wakefulness. When a desynchronized low-amplitude electrical activity was recorded in the parietal and visual cortex, either SWD or jerks were observed. The SWD appearance prevented a jerk. If the discharge appeared between jerks, the interval between jerks increased. Particularly important is the fact that after subtraction of the discharge duration, the distribution of intervals between jerks became the same as in the absence of the SWD. This finding shows that an SWD just interrupts the development of a jerk. That is, when the discharge is over, the jerk develops from the level at which it was stopped by the discharge rather than from the initial level of excitation.

Action Potentials↗
PubMedDate not supplied

[Temperature reactions of the cerebral cortex in the rat and the distant effect of an experimentally evoked excitatory focus].

By means of dynamic thermovision method, distant reactions of the cerebral cortex were studied in white rats appearing under local chemical action (2% KCl). Besides the previously described temperature wave SD (T-wave), in these conditions in the contralateral hemisphere local areas of warming up (0.2-0.3 degrees) were observed symmetrical with the place of stimulation. Under local chemical action, latent foci of excitation were revealed on dynamic thermal maps of the brain surface in the areas of the same or contralateral hemisphere, distant from the places of stimulation. During creation of two K+ foci a change was observed of place of T-wave appearance and of the usual order of its propagation over the cortex and also the formation of a focus of prolonged temperature fluctuations in the place of two T-waves meeting. On the basis of the obtained data a number of questions is discussed on the forms and mechanisms of distant effects in the CNS.

Analog-Digital Conversion↗
PubMedDate not supplied

[Spectral and coherence EEG analysis of rats differing in the level of seizure readiness].

The resting EEGs of several brain structures (motor and visual cortex, caudate nucleus and intralaminar thalamic nuclei) were submitted to spectral and coherence computer analyses in two rat strains. Genetically predisposed to convulsive state KM rats were shown to differ from nonpredisposed Wistar rats in EEG spectral properties. KM rats EEG pattern was characterized by increase of low frequencies (1-2 Hz) power and decrease of faster activity (5-12 Hz) power in cortical spectrograms as well as by decrease of caudate nucleus EEG absolute power. The coherence value between cortical or subcortical structures at below 4 Hz was intensified in KM rats. Reinforcement of cortical auto-oscillating properties manifested by ECoG synchronization in cortical-thalamic resonance interaction as well as weakening of striatal inhibitory system may constitute neurophysiological mechanisms of enhanced convulsive readiness. The probable role of mediator imbalance in these mechanisms is discussed.

Acoustic Stimulation↗
PubMedDate not supplied

[Evaluation of heat production during propagation of the depression wave].

A mathematical model is proposed to describe a heat wave accompanying the spreading cortical depression wave in the large brain. The model takes into account heat production of neurons, thermal transmission with thermoconductivity and volume thermal losses. The model fits well for the wave shape and permits one to estimate heat production which is about 4-20 J/g X min.

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