[Intralimbic evoked potentials and excitatory cycles under conditions of food and defensive motivations in dogs].
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
G A Grigor'ian
Publications and source records attributed to G A Grigor'ian.
[Instrumental conditioned defensive reflex to electrical stimulation of the hippocampus in dogs].
In experiments on 6 dogs an instrumental defensive conditioned reflex was elaborated to electrical stimulation of the ventral and dorsal hippocampus. This reflex possessed the same characteristics as reflexes to distant stimuli: it became extinguished when the reinforcement was discontinued; it reappeared when the reinforcement was resumed, and it was subject to generalization. In the course of reflex elaboration, the hippocampus function underwent a substantial reorganization. Initially it consisted in inhibition of behavioural reactions; following the reflex elaboration, a general motor activity took place anticipating conditioned paw lift.
Animals↗
[Avoidance mechanisms during self stimulation].
Increased negative discordance of the dominating mode of the pressing duration histogram (PDH), which correlates with the growth of fixed bursts of stimulation is accompanied by a progressive decrease in the reinforcing properties of self-stimulation (SS), avoidance of the pedal and at the same time by a change of behavioral grooming reactions in the intervals between SS for search and consummatory reactions. Hunger considerably shortens the preferable duration of pressing or leads to the appearance of an additional mode on the PDH. With the change of the dominating PDH mode from positive discordance to a negative one, brain stimulation acquires aversive properties which are apparently due to the activation of the mechanisms of specific motivations.
Animals↗
[Assessment of the reinforcing properties of self stimulation in rats using the "discordance" index].
Histogramms of the duration of pedal pressing (PDH) as a function of stimulation parameters, were studied in fifteen rats with electrodes inserted in the lateral hypothalamus and with fixed series of brain stimulation. The "discordance" parameter was used to estimate the changes in PDH modes relative to the moment of the end of brain stimulation. It was found that an increase in the stimulation charge brought about a gradual replacement of positive discordance (the duration of pressing exceeds that of stimulation) by a negative one (duration of pressing is shorter than that of stimulation) and a rise of negative discordance. It is assumed that in the case of positive discordance the duration of the total brain stimulation possesses reinforcing properties, while in the case of negative discordance the beginning of the stimulation possesses reinforcing properties, and its continuation becomes negative.
Animals↗
[The role of biological needs in the genesis of self stimulation].
It has been found in fifteen rats with monopolar electrodes implanted in the lateral hypothalamus that after stimulation of the brain with bursts of electrical pulses of fixed duration, with definite combinations of stimulation parameters, the histograms of the duration of pedal pressing have a polymodal appearance. As the combinations of stimulation parameters change, the number, position and magnitude of the modes undergo a corresponding change. With unchanged parameters of stimulation the form of pressing duration histogram does not change significantly. A conclusion has been drawn that the modal duration of pressing in the course of self-stimulation is apparently an effector manifestation of central integration of reinforcing excitation. In a state of hunger and thirst as well as under weak nembutal anaesthesia, the previously monomodal histograms of the pressing durations produce additional modes which diminish and disappear after satiation and discontinuation of the nembutal effect. It is assumed that at least some modes of the histograms of the pressing duration of self-stimulation may reflect an activation of the systems of biological needs.
Animals↗
[The relationship between the frequency of self-stimulation and parameters of the stimulus].
The dependence of self-stimulation frequency on stimulation parameters (current intensity, stimulation frequency, pulse duration, duration of pulse bursts) was studied in fifteen rats with monopolar electrodes implanted in the lateral hypothalamus, using rectangular current pulses for brain stimulation. All the experiments revealed qualitatively similar response surfaces to the combined change of stimulation frequency and pulse duration Self-stimulation frequency is connected in a non-linear way with the "specific charge" per unit of time, and in an approximately linear way, with the duration of the pulse burst. Regression equations are determined which precisely enough described the kind of response surface (R =0.7 to 0.95).
Animals↗
[Evoked potentials of the brain limbic structures during a change in the motivational state of dogs and during the realization of unconditioned reflex reactions].
In experiments on 6 dogs it has been shown that in the EPs led from the hippocampus in response to electrostimulation of limbic structures and from the latters at the hippocampus stimulation, initial negativity, after positivity and late negative wave are the most stable components. At transition from one functional state to another two latter waves are subjected to the greatest changes. Amplitude-temporal characteristics of intralimbic EPs depend on the level and type of motivation, degree of emotional stress and properties of conditioned reaction.
Animals↗
[Stress and drug dependence (animal studies)].
This review describes a role of stress in formation of the primary drug-taking behaviour and the effects of stress on a drug-seeking behaviour after withdrawal of drugs. The psychophysiological and neurochemical mechanisms of the rewarding and aversive states during a drug taking and after its withdrawal are considered. A role of separate neurotransmitters and their interactions in formation of drug dependence and the effects of stress on neuroadaptive changes in these neurotransmitter systems are described. A review of the structures involved in mediation of the stress effects and a drug-seeking behaviour is also discussed.
Adrenocorticotropic Hormone↗
[General cognitive ability. Current state and prospects for further investigations].
The paper reviews general cognitive ability (g), the ways of its measurement, and genetic and behavioural aspects of its investigations. The criteria for assessment of cognitive abilities in animals are also suggested and described. Based on these criteria the new behavioural methods and procedures are developed for investigation of general cognitive ability.
Animals↗
[General cognitive ability. Some new approaches in mice].
In this paper some new methods for studying of general cognitive ability, g, and their experimental testing on mice are proposed. Instead of techniques based on learning processes with application of many trials and gradual elaboration of a habit, the proposed methods allow to assess behaviour by using only one or a few trials and to compare such behaviour with conceptual activity.
Animals↗
[A new simplified model of discrimination learning in mice].
A new technically simple and procedurally easy model of discrimination learning in mice has been proposed. The model allows to reach a quick rate of learning; to use the various characteristics of objects (form, color, size, etc) within the same sensory modality as a conditional stimulus; to transfer discrimination from one signal characteristic to the other (for instance from a color to a size); and to assess behaviour in a situation closely approached to conditions of the natural environment.
Animals↗
[The problem of reinforcement. From behavioural control to neurochemical background and the development of psychopathologies].
At the first part of the paper a number of conceptions about psychophysiological mechanisms of reinforcement and its role in brain system activity is presented. At the second part, a significance of the mesolimbic and mesocortical dopaminergic systems in reinforcement process and the relationships between different components of behavioural control (signal, memory, actions, etc.) and intensity of dopamine transmission at the level of n. accumbens and frontal cortex are considered. At the final part of the paper the results of development of some psychopathologies and marginal conditions, related to a low or high content of dopamine in the above-mentioned structures, and possible neurophysiological mechanisms of their formation are presented.
Behavior↗
[The role of the lateral and medial hypothalamus in reproducing a motor reaction as the signal during the acquisition of classical conditioned reflexes].
In experiments on three dogs there was shown that testing electrostimulation of the lateral hypothalamus reproduced the motor reaction which is a signal stimulus at elaboration of classic alimentary conditioned reflexes (CRs) and did not reproduce it at elaboration of classic defensive CR. Testing electrostimulation of medial parts of the hypothalamus reproduced, as LH electrostimulation the "signal" motor reaction, but in less percentage of cases, during elaboration of classic alimentary CRs and did not reproduce it at elaboration of classic defensive CRs. The reproduction of the signal motor reaction at LH electrostimulation is connected with activation of backward conditioned connection from motivation structures of the hypothalamus to representation of the signal stimulus in the motor cortex.
Animals↗
[The role of the lateral and medial hypothalamus in reproducing food and escape instrumental reactions].
In experiments on two dogs it has been found that testing electric stimulation of the lateral hypothalamus reproduces instrumental movement in case of elaborated alimentary instrumental conditioned reflexes (CR) to a tone and does not reproduce it at elaborated acid-defensive instrumental CR. Under testing electric stimulation of the medial hypothalamus the instrumental movement practically is not reproduced neither in alimentary nor in defensive situation. Appearance of instrumental movement at LH electro-stimulation in alimentary situation is connected with activation of backward conditioned connection from motivation "alimentary" LH centre to representation of this movement in the motor cortex.
Acoustic Stimulation↗
[Molecular-chemical basis of emotional states and reinforcement].
In this paper we have attempted to relate and explain the activity of the brain different integrative levels, which ends up with occurrence of a goal-directed behaviour and reinforcement. Two main mechanisms of responding to subjects and events of external environment, as rapid executive reactions and slow motivational-emotional states, have been marked out. Each mechanism gets its own neurochemical basis, ways of information transmission and molecular-genetic programs for the specialized metabolic reactions. Together both mechanisms form a unique spatial-temporal continuum of neural processes aimed to produce the beneficial activity and reinforce it by subjectively perceived emotional states.
Animals↗
[Individual typological features reflected in different stages of learning and related changes in dopamine transport in the mesolimbic brain].
A hypothesis is proposed according to which there is a strong similarity between the individual typological features of animals (humans) and different stages of learning processes. The hypothesis is supported by the results of comparisons of psychophysiological and neurochemical indices of different stages of conditioning and various typologies of higher nervous activity. Such comparisons reveal a high similarity between the generalization phase and impulsivity, the phase a learned conditioned reflex and self-controlled behaviour, and overlearned CR and a state of "psychosis". Functional states close to pathology and possibilities of development and manifestation of several psychotic states depending on psychophysiological and neurochemical organization of learning processes are also considered.
Animals↗
[Intralimbic evoked potentials in the formation of an instrumental food conditioned reflex to hippocampal electrostimulation in dogs].
In dogs with the electrodes implanted in the hippocampus, amygdala, septum and hypothalamus an instrumental alimentary conditioned reflex (CR) was elaborated to electrostimulation of the hippocampus. Intralimbic evoked potentials (EPs) were studied during the elaboration and extinction of this reflex and during stimulations of limbic structures conducted with the purpose of CR generalization checking. Late EP components in the lateral hypothalamus and central nucleus of the amygdala changed during CR elaboration and extinction and in the hippocampus during amygdala testing. In both cases the amplitude of trace positivity and of slow negative wave was less, when during stimulation of the structure an instrumental movement was initiated than at its absence.
Animals↗
[Haloperidol does not alter a choice strategy for reinforcement value in cats].
A blockade of the dopaminergic D1/D2 receptors by systemic administration of haloperidol (0.05-0.5 mg/kg) produced a dose-dependent increase in inhibition of conditioned alimentary behavior in cats under conditions of choice between a valuable delayed reward and a less valuable immediate reward. Administration of haloperidol produced a progressive decrease in the number of effective instrumental reactions, but did not affect the choice between short- and long-latency reactions and their mean latencies. The data obtained do not support a hypothesis that the blockade of dopaminergic receptors shifts behavior towards impulsive reactions. The reasons why the results do not support the hypothesis are discussed.
Animals↗