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Biomedical subjects

T N Oniani

Publications and source records attributed to T N Oniani.

At least 19 recordsLinked to original sources
PubMed1989

The influence of electrocoagulation of the septum and section of the entorhinal cortex on general behaviour and memory in cats.

In chronic experiments on cats it was shown that the lesion of the medial part of the septum does not result in the "septal syndrome"; the ratio of the different sleep-wakefulness cycle phases remains within the baseline values; the acquisition, retrieval and extinction of instrumental alimentary conditioned reflexes proceed normally; the delayed conditioned reflexes are impaired. Massive septal lesion, including its lateral part, leads to the development of the "septal syndrome"; there are changes in the structure and percentage of the different sleep-wakefulness cycle phases; the acquisition and extinction of instrumental alimentary reflexes with the sound discrimination are markedly retarded; the performance of delayed conditioned reflexes is completely destroyed. The section of the entorhinal cortex produces an increase in the number of repeated errors and perseverative movements during performance of instrumental alimentary reflexes, the deceleration of the acquisition and extinction of instrumental alimentary reflexes, complete disturbance of the delayed conditioned reflexes and does not affect the sleep-wakefulness cycle. The problems of the role of the hippocampus and its main inputs in the regulation of the short-term operative memory in the "pure form" as well as the significance of the descending influence of the hippocampus on the regulation of general animal behavior were also discussed.

Animals↗
PubMed1989

[The organization of the neuronal activity of the cortical cingulate gyrus in the waking-sleep cycle].

Dynamics of the neuronal activity of the cingulate gyrus (CG) in the sleep-wakefulness cycle (SWC) was studied in free-moving cats. Most of neurons (65.4) discharged with high frequency during active wakefulness (AW) and emotional stage of paradoxical sleep (PS); the frequency of discharges decreased during the passive wakefulness (PW) and slow-wave sleep (SWS). 15% of neurons showed opposite dynamics of the activity. They fired more intensively during the SWS. 19.6% of neurons showed no statistically significant difference in the discharge frequency of different phases of the SWC. Most of neurons (75.2%) regularly changed the pattern of discharges at a chang of the phases of the SWC. In particular, those neurons discharged by single spikes, more or less uniformly distributed in time, against the background of AW and PS. With the development of the SWS neurons began to discharge according to the cluster-pause principle. During the development of the short fragments of the EEG arousal, most of neurons either decrease (42.6%) or did not change (50.4%) the activity. The involvement of the CG in the regulation of the SWC is discussed.

Animals↗
PubMed1988

[Effect of monoamine oxidase inhibitors with a broad range of action on the structure and phase ratio of the wakefulness-sleep cycle in the cat].

The monoamine oxidase (MAO) inhibitors disturb the structure of the sleep-wakefulness cycle and its ultradian rhythms by prolongation of the slow-wave sleep, complete suppression of the paradoxical sleep (PS) and considerable shortage of the wakefulness phase. When synchronizing action of MAO inhibitors has stopped prolongation of wakefulness is observed both before and during partial recovery of the PS. This fact is considered as an indication of the accumulation of a need of wakefulness in the course of its partial deprivation by MAO inhibitors. MAO inhibitors exert a particularly strong effect on the PS producing long-term suppression of its tonic and phasic components. Complete inhibition of the PS is apparently due to selective deterioration of the functional state of its trigger mechanisms.

Activity Cycles↗
PubMed1988

[Dynamics of unit activity of the gigantocellular tegmental field in the sleep-wakefulness cycle of rats].

Computer analysis and statistical processing of the unit activity showed that the majority of neurons (65.2%) in the gigantocellular tegmental field were discharging with high frequency during active wakefulness and paradoxical sleep as compared to slow-wave sleep in unrestrained rats. 11.6% of the neurons revealed an inverse pattern of activity: they discharged more intensively during slow-wave sleep, their firing rate decreasing during active wakefulness and paradoxical sleep. Some neurons (23.2%) were found which fired intensively during active wakefulness, their firing rate decreasing both in slow-wave and paradoxical sleep. Involvement of the gigantocellular tegmental field in the neurophysiological mechanisms of phases and stages of the sleep-wakefulness cycle is discussed.

Animals↗
PubMed1988

[Neurophysiological analysis of the effects of selective deprivation of paradoxical sleep].

Neurophysiological analysis of the effects of selective and total paradoxical sleep deprivation (PSD) involving the replacement of paradoxical sleep (PS) phases by equivalent (as to duration) episodes of wakefulness is carried out. In contrast to the "classical" method of momentary awakening of the animal, a new method does not lead to: (1) the accumulation of PS need associated with more frequent PS onsets during deprivation; (2) PS rebound in a postdeprivation period; (3) dissociation of PS components, i.e. their occasional occurrence in other phases of the sleep-wakefulness cycle due to the phenomenon of self-deprivation; (4) increase in the rate of pontogeniculo-occipital (PGO) spikes, eye movements and heart rate during PS phases in the postdeprivation period. The application of selective and total PSD techniques caused no noticeable changes in the functional state and integrative activity of the brain, the latter warranting its successful use for treatment of some psychoneurological disturbances in clinics. The assumption has been advanced about the similarity of the neurochemical changes forming the need both for wakefulness and PS.

Animals↗
PubMed1988

[Dynamics of the neuronal activity of the posterior hypothalamus during a phase shift of the wakefulness-sleep cycle].

Dynamics of neuronal activity of the posterior hypothalamus in the sleep-wakefulness cycle was studied in free moving cats using mobile metal microelectrodes. Computer analysis and statistical treatment of the data have shown that the majority of neurons (89.3%) in the above-mentioned area discharge with high frequency during active wakefulness and emotional stage of paradoxical sleep; the frequency of discharges decreases during passive wakefulness and nonemotional stage of paradoxical sleep and is the lowest in the slow wave sleep though it has been higher than at the other states. Comparatively small number of neurons (3.6%) show opposite dynamics of the activity. They fire more intensely during slow wave sleep and the frequency of discharges decreases during active wakefulness and paradoxical sleep. In posterior hypothalamus some neurons (7.1%) are found which fire intensely during active wakefulness as compared with slow wave sleep and paradoxical sleep. The neurophysiological mechanisms for regulation of the sleep-wakefulness cycle and the involvement of posterior hypothalamus in this process are discussed.

Action Potentials↗
PubMed1987

[Effect of various monoamine oxidase inhibitors on the structure of the sleep-wakefulness cycle of the cat].

The effect of some monoamine oxidase inhibitors (phenelzine, transamine, nialamide) on the structure of the cat sleep--wakefulness cycle involved an increase of slow-wave sleep at the expense of totally inhibited REM sleep and substantial reduction of wakefulness. Following this effect, selective rebound of wakefulness occurred against the background of total or partial absence of REM sleep. The partial deprivation of wakefulness induced with monoamine oxidase inhibitors seem to entail an accumulation of a specific need in the given physiological state, the gratification of which is effected through its rebound in the post-deprivation cycle.

Animals↗
PubMed1984

Does paradoxical sleep deprivation disturb memory trace consolidation?

The effect of water tank PSD on memory in the passive avoidance test as well as on open field behavior was studied in rats. The effect of combining water tank PSD with a period of normal sleep-wakefulness cycle or with PSD by non-emotional awakening was investigated in a special series of experiments. It is concluded that PSD, even by the water tank procedure, does not disturb trace consolidation and formation of long-term memory in the passive avoidance test. However, a change in the correlation of motor-exploratory activity and fear reaction, due to the stressful situation intrinsic in the water tank PSD procedure, does not allow the animals to reach comparatively long temporal criteria in the passive avoidance test.

Animals↗
PubMed1984

[Effect of partial deprivation of slow-wave sleep on the structure of the sleep-wakefulness cycle].

In cats, partial (35% and 55%) deprivation of slow-wave sleep by way of inducing fragments of isolated EEG wakefulness in response to electrical stimulation of brain-stem activating structures, was shown to lead to an enhancement of behavioral sleep and reduction of paradoxical sleep. The reduction of paradoxical sleep is particularly obvious if the deprivation of slow-wave sleep is induced by fragments of behavioral wakefulness. In these situations no rebound of paradoxical sleep is observed in post-deprivation period. The causal interrelationships and interdependence of different phases of the sleepwakefulness cycle as well as interaction of EEG and behavioral mechanisms of sleep and wakefulness, are discussed.

Animals↗
PubMed1984

[Dynamics of the neuronal activity of midbrain reticular nuclei in the sleep-wakefulness cycle].

Dynamics of neuronal activity of the mesencephalic reticular nuclei (n. cuneiformis, n. parabrachialis) in the sleep-wakefulness cycle was studied in free moving rats using mobile metallic microelectrodes. Computer analysis and statistical treatment of data have shown that the majority of neurons in the above-mentioned reticular nuclei of the mesencephalon (76% and 66%, respectively) generate with high frequencies during active wakefulness and emotional stage of paradoxical sleep; the frequency of discharges is less during passive wakefulness and nonemotional stage of paradoxical sleep, while in the slow-wave sleep they exhibit the least activity. Comparatively small number of neurons (24%, 15%) show inverse dynamics of activity. They fire more intensively during slow wave sleep and the frequency of discharges decreases during active wakefulness and emotional stage of paradoxical sleep. During quiet wakefulness and nonemotional stage of paradoxical sleep the neuronal activity attains the level observed in a slow-wave sleep. In n. parabrachialis some neurons are found which fire intensively during active wakefulness, the frequency of their discharges decreases in passive wakefulness and slow-wave sleep and is the least in paradoxical sleep. The similarity and difference of the neurophysiological mechanisms of phases and stages of the sleep-wakefulness cycle are discussed.

Animals↗
PubMed1984

Some aspects of conditioned reflex activity during sleep.

Acquisition, retrieval and extinction of instrumental alimentary reflexes during various types of sleep was studied in cats with metallic electrodes chronically implanted in different brain structures. The possible acquisition and extinction of a defensive conditioned reflex with the onset of paradoxical sleep (PS) serving as a conditioned signal and painful electrical stimulation of the skin as unconditioned was investigated. Results suggest that: (i) in the presence of a high food motivation the conditioned signals delivered during sleep cause the retrieval of previously acquired instrumental alimentary reflexes, and in PS the brain is capable of discriminating conditioned signals more accurately than during slow wave sleep, (ii) after a conditioned reaction to one of two conditioned signals is extinguished through non- reinforcement, the second signal remains effective, causing an instrumental alimentary reflex, (iii) the extinction of instrumental alimentary reflexes effected during sleep is not retained after the animal's awakening, whereas the extinction of a defensive conditioned reflex is retained, (iv) PS may serve as an endogenous conditioned signal during the acquisition of a defensive conditioned reflex. Thus motivational processes developing during PS are effective endogenous stimuli eliciting past experience dreams.

Animals↗
PubMed1980

Factors of extinction of alimentary instrumental conditioned reflex.

Observations were made on the animal's behavior and dynamics of electrical activity in the neo- and archipaleocortex during acquisition of sound discrimination under different experimental conditions and subsequent extinction. On the basis of analysis of the data obtained the following conclusions were drawn: (1) In pre-satiated cats even hundreds of applications of conditioned stimuli without food reinforcement do not lead to extinction of the conditioned reflex. Sound discrimination is not disturbed either. (2) Conditioned reflex and discrimination are not disturbed at repeated (over 300) application of conditioned sounds without food reinforcement provided the animal is hungry and is not allowed to approach the feeders. (3) Extinction of the conditioned reflex is achieved only when the animal is allowed, in response to conditioned stimuli, to approach the feeders where there is no reinforcing portion of food. (4) Stimulation of some mesodiencephalic structures results in the restoration of the extinguished alimentary instrumental reflexes and discrimination. (5) Functional inactivation of the hippocampus by way of induction of epileptiform discharges does not prevent the acquisition and extinction of conditioned feeding behavior. (6) Septal lesions do not prevent the acquisition, but extinction is tangibly delayed (7). It is concluded that the factor of extinction is the recognition that feeders contain no food rather than non-reinforcement, i.e. no food intake. On the basis of analysis of the dynamics of electrical activity in the neo- and archipaleocortex, as well as the mesodiencepalic electrical stimulation effects, some aspects of neurophysiological mechanisms of extinction are discussed.

Animals↗
PubMed1980

Neurophysiological processes underlying short-term memory in non-consolidating form in cats.

Dynamics of electrical activity in the neo- and archipaleocortex in response to directing and triggering conditioned signals during delayed responses was studied in cats with chronically implanted electrodes. Dynamics of unit activity of some mesencephalic structures was also studied in rats in response to sensory stimuli and during the sleep-wakefulness cycle. Neurophysiological analysis revealed two components of trace underlying the performance of CS discrimination delayed response. The first one is reflected in the electrical activity changes in the neo- and archipaleocortex (desynchronization of electroneocorticogram and increase in the hippocampal theta rhythm), and may be named a dynamic component. The other, usually a longer component of the trace is not reflected as the above-named changes in the EEG, yet it can be detected by means of a triggering CS or electrical stimulation of motivational mesodiencephalic structures. On the basis of control experiments it is supposed that the neurophysiological basis of the second trace component might be plastic changes in synapses leading to the improvement of conduction in the differentiated nervous circuits of the brain through the selective activation of which both CS discrimination and remembering during DR performance are effected.

Animals↗
PubMed1977

On the functional significance of sleep.

Some aspects of the functional significance of sleep are considered. These involve studies on (i) the dynamics of electrical activity in the neo- and archi-paleocortical structures of the brain in the sleep-wakefulness cycle, (ii) the effect of selective deprivation of different sleep phases on the sleep-wakefulness cycle, (iii) effect of stimulating synchronizing and desynchronizing systems on the sleep-wakefulness cycle, and (iv) the dynamics of emotional tension in the sleep-wakefulness cycle. Analysis of our findings and their comparison with those reported in the literature support a hypothesis that every phase in the sleep-wakefulness cycle operates in two directions; it withdraws the factors formed in the previous phase which are potentially aimed at disturbing brain homeostasis; and, at the same time, it forms new antihomeostatic factors, withdrawal of which requires the triggering and work of a subsequent phase. The triggering links of the systems regulating each phase are very sensitive to the factors formed in the preceding phase. Therefore, in normal conditions the anti-homeostatic factors fail to attain a critical level of disturbance of homeostasis of the brain, since the threshold for their activation is far lower than the critical level of homeostatic disturbance. Activation of the triggering links of the paradoxical phase and wakefulness seems to be mediated through the same anti-homeostatic factors formed in the orthodox phase. However, the threshold for activation of the paradoxical phase is lower than that of wakefulness. As a consequence, the orthodox phase readily passes into the paradoxical. The latter, effectively reducing the antihomeostatic factors formed in the orthodox phase, prevents the onset of undue awakening that would have been undesirable because there would have been insufficient time for inactivation of the anti-homeostatic factors formed during wakefulness.

Brain↗
PubMed1976

[The effect of low-frequency electric stimulation of the caudate nucleus on the electrical activity of the cortex and on the sleep-wakefulness cycle].

In cats, the effect of low-frequency electric stimulation of the caudate nucleus on electric activity of neo- and archipaleocortex and on wakefulness-sleep cycle, was studied. The data obtained suggest: 1) at threshold and suprathreshold single electric shocks applied to the caudate nucleus they evoked potential occurs more readily in the sensorimotor area of the neocortex than in the dorsal hippocampus. At 2-6/sec stimulation the evoked potentials in the hippocampus are facilitated and become very stable, whereas in the sensorimotor cortex the most obvious responses occur at the 6-8/sec frequency. However, the evoked potentials are variable in the sensorimotor cortex, and at prolonged 8-12/sec stimulation spindle activity soon develops; 2) behavioral correlate of the synchronized activity in the neo- and archipaleocortical structures during low-frequency stimulation of the caudate nucleus, may involve development of drowsiness with the cessation of stimulation, however, both the EEG and behavioral signs of the drowsiness disappear. The onset of drowsiness following withdrawal of the caudate stimulation, is a rare phenomenon only occurring because of an occasional coincidence of the stimulation with the spontaneous onset of natural sleep; 3) low-frequency caudate stimulation entailing the ECoG synchronization does not cause the transition of paradoxical phase into the slow-wave phase of sleep, and as soon as the stimulation ceases its normal structure recovers. However, if the stimulation of the caudate nucleus is repeated several times in one paradoxical phase, this would shorten the subsequent slow-wave phase and accelerate the onset of the next paradoxical phase; 4) prolonged low-frequency stimulation of the caudate nucleus causing the ECoG synchronization results in a considerable change of wakefulness-sleep cycle in the post-stimulation period: a decrease in the total time of slow-wave sleep due to shortening of its different phases, and an increase in the total amount of paradoxical sleep because of the onset of its phases is rendered more frequent. This effect is more obvious in the first half of the 8-hr cycle.

Animals↗
PubMed1975

Effects of electrical stimulation of the mesencephalon and diencephalon on the paradoxical phase of sleep.

During paradoxical sleep electrical stimulation of the mesencephalic reticular formation and emotiogenic structures in the mesencephalon and diencephalon produced depression or an increase in the theta rhythm of the hippocampal and entorhinal electrical activity. However, stimulation not involving behavioral arousal did not cause a transition from paradoxical phase into slow wave sleep. The cessation of stimulation restored the normal structure of the paradoxical phase. Stimulation of the reticular formation causing the depression of the hippocampal and entorhinal theta rhythm without behavioral arousal did not affect duration of the paradoxical phase, which was shortened, however, by electrical stimulation of the emotiogenic structures evoking an increase in the hippocampal and entorhinal theta rhythms. Stimulation of ventromedial hypothalamus or septum (during wakefulness inhibiting motivational behavior and emotional stress) caused transition from the paradoxical into slow wave sleep. This is probably caused by a decrease in emotiogenic stress, which during the paradoxical phase is usually on a high level.

Animals↗