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[Effect of the destruction of the entorhinal region of the cortex on the conditioned reflex activity of animals].

A study was made of the influence of ablation of the entorhinal cortex on conditioned reflexes to present and trace stimuli. Ablation resulted in a long-lasting and considerable disturbance of differentiation of time macrointervals. After the operation, elaboration or restoration of the conditioned reflex to time was delayed five or six times as compared with intact animals. There was no change in the state of motor alimentary conditioned reflex to different (single or complex) present stimuli regardless of whether the ablation was performed after or before the elaboration of conditioned reflexes. Similar results were obtained in animals of different phylogenetic groups (rats and dogs).

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Corticohypothalamic relationships during the development and realization of the conditioned reflex.

The influence of motivational, emotiogenically positive and emotiogenically negative structures of the hypothalamus on the development and realization of conditioned reflexes was investigated in the experiments on dogs, cats, and rats. It was shown that the motivational structures primarily increase excitability of cortical neurons during the development of the conditioned connection, while the emotiogenically negative and emotiogenically positive structures increase the efficiency of synapses. A high degree of correlatedness of the averaged evoked responses to the conditional stimulus in the hypothalamus and new cortex is characteristic for the consolidated conditioned reflex. Direct stimulation of the motivational-alimentary zones of the hypothalamus reproduce food-procuring conditioned reflexes in dogs, while stimulations of the emotiogenically negative zones reproduce defense conditioned reflexes. Stimulation of the emotiogenically positive zones does not reproduce either; however, an intensification of the activity of neurons of the hypothalamus was recorded in rats during the successful accomplishment of the conditioned reaction of avoidance of an aversive stimulus. In cats which are capable of restraining a conditioned motoric reaction for the sake of obtaining a preferred food, the "motivational", long-latency functional connections between neurons of the lateral hypothalamus and the prefrontal cortex predominate. Short-latency "informational" connections predominate in the "impulsive" cats.

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[A comparison of the effects of single and chronic microinjections of GABA and picrotoxin into the caudate nucleus on the conditioned reflexes of dogs].

The effects on Pavlovian alimentary conditioned reflexes realization of two methods of intrastriatal microinjections--acute (separate) and long-term (chronic) one--are compared in experiments on dogs. Bilateral acute administration and the first week of chronic injection of 45 mcg of GABA into the caudate nuclei produced in dogs a manifest improvement of parameters of the conditioned differentiation inhibition, but only in the next period of chronic treatment an improvement of the positive Pavlovian alimentary conditioned reflex was obtained. The both ways of picrotoxin treatment impaired conditioned behaviour, and this effect was observed after the end of injection. No withdrawal effects were recorded. The data obtained give ground for discussion of the role of striatal GABAergic system in the positive modulation of adaptive alimentary behaviour. The application of novel psychopharmacological method in experimental and clinical fields of investigation is discussed.

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[Formation of an alimentary motor conditioned reflex to photic stimulation in young rhesus monkeys].

It is possible to form a positive motor alimentary conditioned reflex to red colour and a negative conditioned reflex (differentiation) to green, in the young of rhesus monkeys, four-to six-week old, which testifies to their capacity of differentiating these colour stimuli. The orienting reflex takes an active part in the formation of both reflexes. Elaboration in the four-week old monkeys not only of a positive but also a differentiating motor alimentary conditioned reflex attests that at this age the cerebral cortex is already actively exercising the function of an integrator of inhibitory processes, not only of excitation.

Age Factors↗
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[Analysis of the neuronal activity of cortical-subcortical structures of a conditioned reflex].

Neuronal activity of the orbital cortex, the caudate nucleus and the amygdala were studied in chronic experiments on dogs and cats by the method of alimentary and defensive conditioned reflexes. A spatial distribution of neurones involved in the alimentary and defensive conditioned reflexes, was revealed in the caudate nucleus head. The units responding to conditioned alimentary stimuli are localized primarily in the ventral segment. Similarity of responses to surroundings and to trigger conditioned alimentary stimuli was found between the units of the ventral segment in the caudate nucleus head and of the amygdala basolateral part. The influence of stimulation of the amygdala on the orbital cortex units was established in the alimentary conditioned reflex in dogs. A conclusion has been drawn that in elaboration of an alimentary conditioned reflex the neurones of three levels become organized into a definite system, providing for an adequate reaction of the organism to the conditioned stimulus.

Amygdala↗
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[Interaction of instrumental habits in the sphere of heterogeneous conditioned reflex activity].

The phenomenon of interference of one reflex with another was observed in dogs during performance of heterogeneous instrumental conditioned reflexes elicited in a stereotype order. When alimentary conditioned reflexes involving the right-leg movement, were elaborated before the defensive ones involving the left fore-leg movement, then manifestation of the second reflex was preceded by a movement with the right leg. When the elaboration of conditioned reflexes started with defensive reflexes, the opposite was observed: before performing the alimentary reflex, the dogs lifted first the left fore-leg connected with the defensive reflex, and then the right one. Inertia of the nervous mechanism underlying this phenomenon, is based on a tonic increase in the excitability of the corresponding structures.

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[Law of strength ratios in motor conditioned reflexes].

The analysis of motor conditioned reflexes was done on the base of Pavlovian strength law in experiments on monkeys and dogs. It was found that in normal experimental conditions direct strength relations significantly dominate. In extreme conditions which lower the excitability of the brain, direct strength relations sharply deepen, leading to narcotic phase. Comparison of the narcotic phase with other hypnotic phases brings to the understanding of the strength law within a wide range, from direct strength relations to reverse (paradoxical) ones, when narcotic and paradoxical phases are at different poles of the optimal state of the nervous excitability with their different mechanisms.

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[Effect of GABA-ergic substances on the elaboration of conditioned reflexes in rats under negative reinforcement].

Experiments on female rats have shown that gabalid (100 and 200 mg/kg) does not essentially change the formation of the conditioned reflexes in intact animals and in those with an involved caudate nucleus whereas cainic acid injected intraperitoneally (15 mg/kg) and applied to the caudate nucleus deteriorates and when given in a dose of 5 mg/kg improves the formation of the conditioned reflexes. Baclofen (10 mg/kg) inhibits the conditioned reflexes in both intact animals and in those with an involved caudate nucleus, whereas in a dose of 1 mg/kg the drug improves it in intact animals and inhibits it in animals with impaired function of the caudate nucleus. The importance of the GABA-ergic system of the caudate nucleus for the action of GABA-ergic agents on the conditioned reflexes in rats is discussed.

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The participation of mediator and peptidergic systems of the brain in conditioned reflex mechanisms.

New data on the significance of mediator and peptidergic systems of the striatal level in the organization of alimentary conditioned reflexes are presented in this report. The role of acetylcholine-, dopamine-, GABA-and P-ergic systems of the caudate nucleus and the amygdala in the realization of positive and negative conditioned reflexes was investigated. The experiments were carried out on dogs with chemotrodes and microelectrodes implanted in subcortical structures. The results of the experiments with microinjections of the relevant substances into individual subcortical structures showed that activation of the same mediator system in various structures may lead to both unidirectional and multidirectional behavioral effects. On the other hand, the activation of various subcortical mediator systems can lead to identical changes in conditioned reflex activity. The effect of the administration of activators or blockers of a subcortical mediator system depends in many ways on the functional state of the nervous system at the moment of administration and on the localization of the microinjection. It is difficult to predict beforehand the role of various subcortical structures in the organization of integrated behavioral acts. The question of the necessity of studying mediator and peptidergic systems of each subcortical structure in order to understand their significance in the mechanisms of the conditioned reflex is raised.

Acetylcholine↗
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[Pharmacologic analysis of monoaminergic mechanisms of the medial hypothalamus in food-getting conditioned reflexes in rats].

In the study of food-procuring conditioned reflex in rats it was found that microinjection of noradrenaline and dopamine in the medial hypothalamus impedes its realization, prolonging the reflex latency, lowering its value and the number of conditioned food-procuring movements. The effects of catecholamines on food-procuring conditioned activity are specific and effectuated correspondingly via alpha-adrenoreceptors or receptors of the hypothalamic neurones sensitive to haloperidol and aminazine. Local administration of GABA to the hypothalamus prolongs the latency of the food-procuring conditioned reflex, but does not change its value and the number of conditioned food-procuring movements. The effect of GABA is not due to the effect on adreno- and dopamine receptors of the hypothalamus.

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Features of the systemic organization of cortical neurons with different forms of the manifestation of a conditioned reflex to time.

A conditioned food-procuring reflex to time (2-min interval) was developed in cats. The coupled activity of neurons in microareas and between microareas of the motor cortex was compared by cross correlation analysis in different forms of the manifestations of the conditioned reflex: decrease in the amplitude of respiratory movements, increase in amplitude, and food-procuring movement of the paw for several seconds prior to the delivery of the reinforcement. Differences were manifested in the degree of increase in the number of functional associations in the second half of the interval as compared with the first, and, to a still greater degree, also in the frequency with which intervals were encountered with altered structure of the interrelationship between the neurons. The changes observed did not always correlate with the change in the frequency of impulse activity of individual neurons, which was noted substantially less frequently.

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[Conditioned reflexes in rats after 5-minute arrest of blood circulation].

Neurological recovery and conditioned activity were studied in rats resuscitated after five-minute circulation cessation caused by intrathoracal clamp of the heart vascular bundle. The dynamics of disappearance of neurological deficit was evaluated according a scale of 19 parameters of the general state of animals where number 100 meant the death of the brain and number 0 meant recovery. In the course of 8 months after resuscitation, in reanimated rats and simultaneously in intact (control) ones, an alimentary instrumental conditioned reflex was elaborated and then changed to a defensive one; passive and acute extinction of both reflexes was also carried out. In most of the rats the neurological recovery was completed rapidly within 3-4 hours. In reanimated animals, both instrumental conditioned reflexes were acquired in the same way as in the intact rats. Quantitative evaluation of the dynamics of conditioning and extinction allowed to see that elaboration of the alimentary reflex in reanimated rats proceeded faster and its change to the defensive one, and acute extinction of both kinds of conditioned reflexes went slower than in intact animals. A conclusion is drawn that even a short-term circulation cessation compatible with complete and rapid compensation of visible neurological disorders causes long-term disturbances of conditioned activity manifested in weakening of inhibitory processes.

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[Heart rate dynamics during elaboration of a spatial conditioned reflex].

In 20 cats spatial conditioned reflexes were elaborated manifested in the animal's stay on an "active" square of the floor attended in different sessions with stimulation (100 imp/s; 0.3 ms, 2 or 6 V) of the septum, the lateral hypothalamus or the hippocampus. Stimulation of the septum and lateral hypothalamus with a 2 V current resulted in an accelerated heart rate, while a 6 V current produced its slowing down. Self-stimulation of the dorsal hippocampus with a 6 V current produced on initial acceleration of the heart rate with a subsequent gradual slowing down. The data obtained attest that both the sympathetic and the parasympathetic parts of the brain are involved in the formation of positive emotions.

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[Effect of tryptophan and its metabolites on the conditioned reflex activity of the honeybee].

The effect of tryptophane and its derivatives on the rate of elaboration and transformation of conditioned reflexes (CR) to odour, with alimentary reinforcement, was studied in wild bees under two conditions: free movement of the bee or its immobilization (stress situation), by means of genetic models (mutations, successive blocking stages of kynurenin path of tryptophane metabolism). It was shown that mutations eliciting accumulation of free tryptophane and serotonin in the hemolymph of the bees and creating a deficit of kynurenins accelerate the transformation of conditioned reflexes and aggravate the depression of conditioned activity usually elicited in wild bees by monotonous prolonged presentation of conditioned signal. The injections of tryptophane and serotonin (5 mg) produce the same action. Mutations, eliciting accumulation in the hemolymph of the kynurenins (kynurenin and 3-hydroxikynurenin) accelerate, in conditions of immobilization, the formation of conditioned reflexes and delay the process of their transformation, and also contribute to maintainance of a higher (in comparison with the norm) level of the conditioned activity under monotonous presentation of the signal. The same action is produced by the injection of 1 mcg kynurenin.

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[Role of the hippocampal cortex and dorsal ventricular margin in the conditioned reflex behavior of Ophisaurus apodus].

In lizards Ophisaurus apodus, extinction of the motor alimentary conditioned reflex, discrimination of location of visual signals were disturbed, and the ability for reversal of the stimuli signal significance was completely lost following bilateral ablation of dorsal parts of the hippocampal cortex. Elaboration of the motor alimentary reflex was not affected. The extent of disturbances depended on the volume of hippocampectomy. The defect resulting from the bilateral lesion of the dorsal ventricular ridge (DVR) depended on the localization of the lesion. Following lesion of the lateral part of the DVR, which is the site of thalamic visual projections, in addition to disturbances of discrimination of visual signals location and of reversal of their signal significance, elaboration of a motor alimentary conditioned reflex to the location of the signal was also affected. Following a central lesion of DVR, such disturbances were less pronounced, while with medial lesions there were practically none. A conclusion has been made that disturbances of conditioned reflexes due to hippocampectomy and DVR damage, differ in their manifestation and nature: the former are similar to the defect after hippocampectomy in mammals and are, perhaps to the disturbance of the inhibition function, while the latter are primarily due to disturbance of the visual function.

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