Characteristics of higher nervous activity in the suslik Citellus fulvus during its active period

In experiments on active ground squirrels, it was possible to form motor defensive conditioned reflexes and to re-arrange the conditioned reflexes from visual and auditory analysers. It was originally demonstrated that repetitive alteration of the informational content of the conditioned stimuli results in neurotic disturbances in animals.     

Motor alimentary conditioned reflexes and delayed reactions in dogs following destruction of the caudate nucleus]

The characteristics of formation and achievement of motor conditioned reactions were studied in seventeen dogs before and after the lesion of head or body of the caudate nucleus. It has been shown that the degree of higher nervous activity disturbances depends on the localization of injuries in the nucleus, and on the complexity of the tests used. The caudate nucleus exerts a modulating effect on the parameters of motor conditioned reflexes and takes a direct part in the structure of delayed reflexes. Lesion of the caudate nucleus body is attended with more serious disturbances of higher nervous activity than lesion of its head.     

Peculiarities of modifying influence of the factors forming the functional status of the central nervous system on dynamics of the rat higher nervous activity disturbances totally exposed to electron and gamma-radiation at a dose of 100 Gy

The dynamics of using a stabilized motor defensive conditioned reflex of active avoidance in "shuttle-box" in rats after the total influence of high energy electrons and gamma-rays at a dose of 100 Gy and a modifying influence of the two most important factors forming the functional status of the central nervous system: the stage of the conditioned reflex consolidation and typological peculiarities of the higher nervous activity have been investigated. The influence of both types of ionizing radiation has been shown to cause far more profound disturbances of non consolidated conditioned reflexes in comparison with the automatized conditioned reflexes and provoke an inverted picture of disturbances in the animals with opposed peculiarities of the higher nervous activity. The qualitative picture of the dynamics of disturbances that are caused by these types of radiation is identical. In summary, the studied conditions that form the functional status of the central nervous system determine the nature of neuroradiation syndrome to a greater extent than differences in the effectiveness of these types of radiation.     

Stages in the development of neuroses in the dog and effects of preparations with antidepressive and tranquilizing properties

In modelling of neuroses, successive stages of development of this pathology were observed in dogs. The first stage is characterized by circular disturbances of conditioned activity, vegetative shifts of compensatory character and intensification of individual characteristics of behaviour. At the second stage, parallel with sharp disturbances of conditioned reflexes and with vegetative dystonia, a distortion of emotional reactions was observed in dogs. It is essential that resumption of neurotization episodes in experiments on dogs with the second stage of disease promoted a development of depressive-like states. Diazepam corrected the behavioural and vegetative shifts at the first stage of neurosis. Non-typical antidepressants eliminated the manifestation of symptoms complex of the disease, especially at prolonged treatment.     

The role of the orbital cortex in feeding behavior]

It has been found that extirpation of the orbital zones of the cerebral cortex in dogs in which the structures of the limbic and striate levels of nervous integration were previously ablated, produced more profound disturbances of the higher nervous activity than the previous operations. Not only conditioned positive and inhibitory reactions were affected, but unconditioned alimentary reflexes as well, while food motivation sharply decreased. Further experiments on the operated animals and could go on, only when alimentary excitability was enhanced. A conclusion has been drawn that the orbital zones of the cerebral cortex are directly related to the achievement of an integrated alimentary behavioral reaction.     

Neurotic disorders in monkeys during increased stress on analytic-synthetic processes

It has been shown in experiments on three rhesus monkeys that an enhanced stress of analytical-synthetic processes consisting in learning to differentiate a sequence of tones, leads to neurotic disorders of monkeys higher nervous activity. They are manifested individually and consist in disturbances of general behaviour, in forced movements, breakdowns of differentiations, the missing of positive responses in the previously elaborated conditioned stereotype and in typical dynamics of the formation of positive and negative conditioned reflexes to a chain of tones (2000 + + 4000 c/s; 2000 + 2000 c/s; 4000 + 2000 c/s; 4000 + 4000 c/s).     

The effect of a decrease in cerebral noradrenaline concentrations on the formation and fixation of temporary connections]

A sharp drop in the noradrenaline content (Na) in the brain of mice does not prevent the elaboration and fixation of relatively simple conditioned reflexes, but considerably disturbs the elaboration of more complex conditioned reflexes with delayed reinforcement. The decrease in the NA content in the brain does not appear to influence directly the process of consolidation of temporary connections; impaired fixation of relatively more complex forms of temporary connections is of a secondary nature and is due to disturbances in their formation.     

Vector representation of associative learning

I. P. Pavlov [12] has shown that conditioned reflexes are selective both with respect to conditioned stimuli and to conditioned reflexes elicited by those conditioned stimuli. At the neuronal level selective aspects of conditioned stimuli are based on detectors selectively tuned to respective stimuli. The selective aspects of conditioned reflexes are due to command neurons representing specific unconditioned reflexes. It can be assumed that conditioned reflexes result from association between selective detectors and specific command neurons. The detectors activated by a conditioned stimulus constitute a combination of excitations--a detector excitation vector. The detector excitation vector acts on a command neuron via a set of plastic synapses--a synaptic weight vector. Plastic synapses are modified in the process of learning making command neuron selectively tuned to a specific conditioned stimulus. The selective tuning of a particular command neuron to a specific excitation vector referred to a conditioned stimulus is a basis of associative learning. The probabilities of conditioned reflexes elicited by conditioned and differential stimuli implicitly contain information concerning excitation vectors that encode respective stimuli. Contribution of the vector code to associative learning was explored combining differential color conditioning with intracellular recording from color-coding neurons. It was shown that colors in carps and monkeys are represented on a hypersphere in the four-dimensional space similar to human color space. The basis of the color space is constituted by red-green, blue-yellow, brightness and darkness neurons.     

Disruption of situational reflexes in experimental neurosis brought on by changes in the space factor

Motor activity elaborated in dogs and consisting of delayed choice reactions in a stochastic system (methods developed by Beritashvili, Hunter) and of rhythmic stereotypes of motor situational reflexes (Kupalov method) was not impaired by changes in spatial parameters of unconditioned stimulus in the stochastic system of choosing one feeding trough out of five. The changes in the spatial arrangement of conditioned and unconditioned stimuli in stable stereotypes led to changes in the behaviour of the animals and experimental neurosis with long-lasting disturbances in the situational conditioned reflexes and the short-term memory.     

Radiation resistance of motor-defensive conditioned reflexes in rats at different stages of the formation and stabilization of a temporary connection

Disturbances were studied of the motor defensive conditioned reflexes in rats radiated in a dose of 100 Gy at different stages of formation and stabilization of temporary connection. In comparison with consolidated (automatized) conditioned reflexes of active avoidance, early stages of formation and stabilization of the temporary connection are characterized by a relatively low resistance against extreme factors and by deepest disturbances of reproduction in radiated animals. The most probable mechanisms of these disturbances are connected with pathological changes of the nervous processes balance towards an increase of excitability and weakening of internal inhibition. Yet a direct radiation influence on the mechanisms of temporary connection reproduction at the second stage of its consolidation cannot be excluded. The role is shown of the emotional reactivity in the above-described processes.     

Effect of streptomycin sulfate on the process of higher nervous activity recovery in dogs in the postanesthesia period]

The effect of streptomycin on recovery of the higher nervous activity during the postanesthesia period was studied on 3 dogs with the method of the conditioned reflexes. It was found that streptomycin sulphate administered in a dose of 25 mg per 1 kg body weight induced no changes in the conditioned reflexes of the non-anesthetized animals. After ether anesthesia disorders in the conditioned and unconditioned reflexes, as well as differentiation was observed during the postanesthesia period. On an average they normalized in 7, 6 and 2 days respectively from the moment of anesthesia. When streptomycin sulphate was used during the post anesthesia period, both the strength and the character of the disorders in the conditioned reflexes changed. In this case recovery of the conditioned and unconditioned reflexes was registered in 2 days, while that of the differential inhibition was registered in 3--7 days from the moment of anesthesia.     

Conditioned reflex activity of pigeons as affected by an infra-low frequency alternating magnetic field

In experiments on 35 pigeons formation and realization was studied of alimentary motor conditioned reflexes under the influence of alternating magnetic field (AMF) with a frequency of 5 and 8 Hz and induction 5100 nTl. It has been found that under the action of such AMF, the percent of adequate responses lowers and the time of motor reaction during execution of motor alimentary conditioned reflexes and of delayed reactions increases. Realization of delayed reactions is disturbed more significantly than that of the present conditioned reflexes. AMF with a frequency of 8 Hz influences more expressively the pigeons conditioned activity in comparison with 5 Hz frequency.     

Conditioned alimentary motor reflexes in cats following destruction of the scorpula]

Bilateral ablation of the putamen results in temporary disappearance of natural as well as artificial conditioned motor reflexes in cats. Further training is necessary for their reestablishment. Restored conditioned reflexes appear with a long latency. After partial bilateral ablation of the putamen, animals that have been trained not only to press a pedal, but also to make a choice between a right or left feeding tray, lose the latter ability. After the reestablishment of conditioned reflexes, the animal makes a correct choice of side only in 68--70% of cases. After total bilateral ablation of the putamen the animals lose artificial conditioned reflexes. The results suggest that the putamen has a close relation to the mechanisms of learning and memory.     

Significance of the relative position in space of associated stimuli for formation and performance of motor conditioned reflexes

In experiments on cats the rate of formation of conditioned reflexes to sound (running to the feeding trough) depended on the spatial interrelations of the paired stimuli: the closer the source of the conditioned signal to the feeding trough, the sooner the formation of the conditioned reflex. It has been assumed that during formation of a conditioned reflex the closing of connection between conditioned and unconditioned stimuli is also attended with the closing of connection between the spatial parameters of the paired stimuli. Experiments with inactivation through cold of the temporal area (cortical representation of the vestibular system) of one hemisphere have shown that such a connection is formed in central parts of the vestibular analyser. When the conditioned reflex is elaborated to one feeding trough, the connection is duplicated by both hemispheres; in reflexes to two feeding troughs (i.e. spatial choice) such connections are lateralized in each hemisphere.     

Effect of activating the putamen on alimentary conditioned reflexes in dogs

The influence was studied of the near-threshold high- and low-frequency stimulation of the putamen on achievement of alimentary conditioned reflexes in dogs. Both low- and high-frequency activation of the examined structure significantly changes the parameters of intermediate secretion, of the salivary conditioned reflexes, without influencing unconditioned ones. Unilateral stimulation disturbs the achievement of positive and inhibitory conditioned reflexes to a greater extent than bilateral one. Difference between the effects of low- and high-frequency stimulation has been revealed.     

Physiologic characteristics of systems of conditioned connections during urgent formation of a program of action]

Examination of preschool age children has shown that instantaneous formation of a system is possible only on the basis of integration of conditioned reflexes, which are differentiated by the nature or strength of reinforcement. Integration of previously elaborated conditioned reflexes is more successful if the initial systems of conditioned connections were in a state of conditioned tonic excitation of an optimal strength. Uniformly strong or uniformly weak stability of all reflexes in the system renders it inert, hence makes it a poor basis for instantaneous formation of a new system.     

Effect of intrauterine ethanol exposure on higher nervous activity and on protein and lipid metabolic indices of the brain in rats

It has been shown that intrauterine effect of ethanol causes alterations of protein phosphorylation, glycoprotein and lipid synthesis in rat brain in late ontogenesis. These alterations correlated with disordered learning and maintenance of the conditioned reflexes.     

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.     

The relationship between the dose of caffeine and the magnitude of conditioned reflex salivation in dogs]

Statistical estimates carried out on a comprehensive experimental material of the archives in the Laboratory of physiology of nervous system types at the Pavlov Institute of Physiology, USSR Academy of Sciences, made it possible to plot average static characteristics of changes in the magnitude of positive conditioned reflexes in dogs, depending on the dose of caffeine. It appeared that conditioned reflexes decreased to some extent after a 0.01 g dose; within the range of 0.05 to 1 g doses, the magnitude of reflexes increased to the maximum; within the range of 0.1 to 0.5 g, their magnitude diminished from the maximum to the normal level, and, finally, a dose of 0.5 g or greater resulted in a drop of the magnitude of the reflexes below the normal level.     

Features of the formation of conditioned secretory reflexes in response to the stimulation of different areas of the caudate nucleus of the dog

Properties were studied of elaboration of conditioned alimentary secretory reflexes to threshold electric stimulation of the caudate nucleus in dogs. The rate of formation of such a reflex and its magnitude were considerably lower than in reflexes elaborated to distant stimuli. Latencies were longer; dynamics of conditioned and unconditioned secretory reactions was similar to that of reflexes to a weak stimulus--light. The motor component of the conditioned alimentary reaction, as a rule, was absent. Characteristics were revealed of formation of alimentary reflexes to stimulation of the dorsal and ventral parts of the head and body of the caudate nucleus.