New data on the correlation of the cardiac and motor components of the instrumental conditioned defensive reflex in dogs

Correlation of heart rate (HR) and conditioned motor reaction (CMR) was studied in dogs with conditioned avoidance reflex by the V. P. Petropavlovski? method. An increase of HR was shown in response to presentation of conditioned sound stimulus reaching maximum directly before CMR beginning. Immediately after the beginning of CMR and further against the background of continuous keeping of the paw in the safety zone, CMR greatly decreases. The CMR changes testify to a heavy weakening of classical conditioned reflex of fear as a result of kinesthetic afferentation signalling about successful keeping of the paw in the safety zone.     

Characteristics of the formation of conditioned defense reactions in monkeys in a primatological chair

Rate of reactions in motor conditioned electro-defensive reflexes and different kinds of internal inhibition, such as acute extinction, differentiation and delay with different retardations, were studied on monkeys in primatological chair. Specificity in formation of conditioned reactions was studied with simultaneous recording of vegetative (respiration and heart rate) and motor conditioned reactions. It has been established, that forming of vegetative and motor components of defensive reflex does not proceed synchronously. At first (2-4 trials) vegetative reactions appear, such as increase of heart and respiration rates. Conditioned motor reactions (legs' jerks) appear later, after 4-9 trials. It has been shown that in monkeys in the primatological chair we have a possibility to form all kinds of negative conditioned defensive reactions: acute extinction, differentiation, delay. Formation of delay inhibition with retardation of 90 s leads to neurotic disorders. But they last only for short periods and disappear after breaks in work. The obtained data are discussed from evolutionary point of view, with a comparative study of specificity of higher nervous activity formation among lower organized vertebrates and with consideration of processes of excitation and inhibition in evolution.     

The dependence of hippocampal electrical activity on the probability of the reinforcement of a conditioned food stimulus

In three dogs the dynamics was studied of changes in the number of instrumental motor reactions, the heart rate and the hippocampus theta rhythm was studied at the change of constant reinforcement to various regimes of probable reinforcement of alimentary conditioned stimulus. At 70 and 50% levels of the reinforcement the instrumental reflex appeared in response to all presentations of the signal stimulus. The greatest decrease in the number of reactions took place at 5% probability. The heart rate both in the intersignal period and at getting of empty feeder depended on the used probability of reinforcement and individual characteristics of animals. The frequency of the theta rhythm in all dogs was the highest at the 30% level and the lowest values were found at the 5% level of reinforcement. The obtained facts testify once more to complex genesis of emotional excitation, the value of which depends both on informational (uncertainty) and motivational (significance of reinforcement) factors.     

Generalization of an instrumental defensive conditioned reflex elaborated to electric stimulation of the hypothalamus in dogs

Generalization of defensive conditioned reflexes elaborated to electrical stimulation of the lateral hypothalamus (LH) was studied in four dogs with electrodes implanted in various structures of the limbic system. Electrocutaneous stimulation was switched off when the dog lifted the foreleg to a definite level. Generalization of the conditioned reflex was manifested in different degrees when testing different formations of the limbic system, or testing one and the same structure, but at different stages of conditioning. Two types of generalization were found: the first one--a well pronounced motor reaction, by its latency, level and duration of lifting the foreleg similar to movements appearing in response to the conditioned stimulus; and the second one--low amplitude or short-term movements differing from conditioned ones. The first type of generalization was observed in response to stimulation of LH, contralateral to the point of signal stimulation, of the ventromedial hypothalamic nucleus, the mammillary bodies and the basal, lateral and to a lesser degree, the central nucleus of the amygdaloid complex; the second type--in response to stimulation of the ventral hippocampus, the medial and lateral septum nuclei.     

Activity of neurons of the motor zone of the cortex during elaboration of a local instrumental defensive reflex in the rabbit

During instrumental defensive reaction of wrist extension in response to a sound (conditioned) stimulus, two types of neuronal responses in the rabbit motor cortex were discovered. The first type was recorded in cells with activity not connected with electromyographic activity of wrist extensors. The reaction consisted in the appearance of inhibitory response at the place of the cancelled electrocutaneous stimulation at animal's performance of conditioned reaction to sound. The second type of responses was shown for a neurone with the activity significantly related to electromyographic activity. In this case the conditioned motor response was accompanied by enhancement of the cellular activation reaction to sound and the increase of spike activity in interstimuli intervals.     

Instrumental heterogeneous responses to 2 successive complex stimuli with a common initial stimulus in the dog

Formation and achievement of heterogenous instrumental reflexes to two consecutive complex stimuli was studied in dogs. Under the action of conditioned complex stimulus tone--Pause--tone, the dogs may be trained not to have a motor response to the first tone presentation, but perform alimentary instrumental reaction only to its repeated administration. Introducing into the experiment not only alimentary but also defensive complex stimulus stone-pause--light resulted in a change in animal's reactions in such a sequence: at first alimentary instrumental reaction was disinhibited under the action of the preparatory stimulus and during the pause, then bieffector responses appeared, further on in most of the dogs motor defensive reactions mainly took place. Trigger stimuli evoked the adequate instrumental reaction.     

Changes in dry weight of pyramidal cell nuclei in the motor cortex during local motor-food conditioning

The formation of a local motor-food conditioned reflex in rats, consisting of pressing on a level with the unpreferred paw, in one session led to a decrease in dry weight of the large pyramidal cell nuclei in the area of representation of that paw in the motor cortex. Frequent repetition of the local motor-food conditioned reflex consisting of pressing on the level with the preferred paw was not accompanied by any such changes. It is suggested that changes in dry weight of the large pyramidal cell nuclei in the area of representation of the unpreferred paw are due to involvement of these neurons in the formation of the new motor coordination (the local conditioned reflex).     

The effect of a vasopressin analog on the reaction of the command neurons in the defensive behavior of the edible snail during nerve stimulation

On the level of snail command neurones of the defensive behaviour an increase was revealed of the amplitude of summary EPSP recorded in command neurones in response to nerve stimulation, an increase of probability of appearance of action potential in the reaction and, under certain conditions, a significant decrease of habituation speed at rhythmic (0.1 Hz) nerve stimulation against the background of peptide. The latter effect was found during comparison of groups of neurones--control neurones and those to which the peptide was presented before the first series of stimulation in the test, i. e. without preliminary elaboration of habituation. The decrease of the speed of habituation concerned both the amplitude of summary EPSP and the probability of action potential appearance in the reaction. All these changes against the background of vasopressin analogue may be the basis of the increase of spike reactions of command neurones of the defensive behaviour and thus the basis of the initiation or the increase of behavioural defensive reactions. The obtained effects were not protracted and took place only in the presence of the peptide in the extracellular medium.     

Conditioned reflex and electrical activities of the hippocampus during the random use of heterogeneous triggering stimuli

In dogs with electrodes chronically implanted in the hippocampus, the conditioned activity, heart rate frequency and spectral characteristics of the hippocampal theta-rhythm were studied in conditions of irregular presentation after a preparatory stimulus now of alimentary and now of defensive triggering conditioned stimuli. It is shown that uncertainty of alimentary or defensive reinforcement is a stronger emotiogenic factor than the action of the triggering defensive conditioned stimulus. Changes in electrical hippocampal activity and autonomous activity depend, along with other factors, on forecasted volume of the forthcoming motor activity. The speed of instrumental conditioned reflexes formation correlates with the hippocampal theta-rhythm frequency, typical for the given animal.     

Ultrasonic vocalization as an indicator of emotional state during active avoidance learning in rats.

Adult male rats subjected to a two-way avoidance task emitted ultrasonic vocalizations (20-30 kHz) both during the presentation of the conditioned stimulus and the intertrial interval. The rate of ultrasonic calling decreased during the 75-trial session indicating that acquisition of the conditioned avoidance response (CAR) was inversely correlated with the rate of vocalization. The rate of acquisition of the CAR was most rapid in those rats that did not emit any vocalization during learning. These data suggest that ultrasonic calling during stressful situations may be sensitive indicator of underlying emotional states that interfere with the acquisition of a complex task.     

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.     

The dynamics of neuronal,autonomic and movement parameters in animals during the reproduction of a learned habit

Data by the authors, as well as from other laboratories, show that the intertrial responses correlated with accuracy of avoidance or feeding behaviour. Moreover our previously data demonstrated the definite changes of neuronal activity, heart rate and respiration during intertrial responses. In this study we investigated the time-course of intertrial response appearance, the pattern of neurophysiological parameters during intertrial periods, and the types of intertrial responses. Experiment 1 showed that different environmental stimuli influenced the level of intertrial responses and successfulness of the avoidance learning. In experiment 2, in which learning and extinction procedures were presented in rabbit passive-avoidance conditioning, two types of intertrial responses were observed; the first type repeated the pain reinforcement, the second one imitated the conditioned reaction of neuronal activity, heart rate, respiration, and moving. These investigations suggest that the processes of intertrial eliciting of avoidance effector programs may be one of the mechanisms of fixation in memory and play an important role in acquisition of more effective results.     

Effect of substance P on behavior in the rabbit and the activity of cortical neurons during training

Subcutaneous injection of substance P to rabbits in a dose of 250 mcg/kg elicited a transitory disappearance of motor reactions to painful reinforcing stimuli and a reduction of their probability to reinforced and inhibitory light flashes, as well as a protracted heart rate increase and decrease of respiration rate. One third of the neurones recorded decreased their background firing level and or excitatory components of the reactions to reinforcement and conditioned light flashes. The decrease was most distinctly seen in the sensorimotor cortex and less pronounced in the visual cortical area and hippocampus. The influence of the substance P on different types of cortical inhibition was not the same. Tonic inhibition of neuronal activity in response to reinforcement was enhanced. Bioelectrical parameters which reflect an enhancement of inhibitory hyperpolarization during elaboration of internal inhibition (i.e. inhibitory firing delays and corresponding background and evoked slow potentials oscillations) were not changed.     

Excitability cycles of direct cortical responses during elaboration of conditioned defense reflexes in dogs]

Direct cortical responses (DCRs) to paired stimuli were studied in chronic experiments in dogs during elaboration of classical and instrumental defensive conditioned reflexes. The DCRs were recorded with 20 to 250 ms intervals between stimuli. Paired and single electrical stimulations of the middle suprasylvian gyrus given with a frequency of one per second were used as conditioned stimuli and were reinforced in a similar way. During electrical cutaneous stimulation of the dog's paw and to an even greater extent during isolated action of the conditioned stimulus the initial negativity of the testing DCR became shorter and the degree of its depression diminished. In the case of a following period of facilitation, its degree became greater. It was higher at a distance of 4 to 5 mm from the point of stimulation than at a distance of 2 to 3 mm. During isolated action of the conditioned stimulus, the degree of facilitation was higher than at the period of the possible action of the unconditioned stimulus. The greatest shorterning of the DCR excitability cycle was observed immediately before and during the conditioned lifting of the dog's paw. Excitability cycles of DCR, and possibly of other evoked potentials as well, are a more sensitive indicator of the function state of the cerebral cortex than responses to single stimuli. For this reason it appears promising to use them in studying conditioned reflexes.     

Integrative properties of parietal cortex neurons of rabbits during the switching of heterogeneous classical conditioned reflexes

The impulsive activity of parietal cortex neurons of rabbits during the elaboration and specialisation of switching-over of alimentary and defensive conditioned reflexes has been studied. There are changes of parietal cortex neurons activity correlated with the stages of switching-over elaboration. The significant differences of the background neurons activity and neurons response to the conditional signal during alimentary and defensive conditioned reflexes have been established. The dominant motivation influences the neurons activity by modulation of background and conditioned activity of neurons. The integrative properties of neurons investigated in switching-over situation are revealed in their ability to summarize the excitation coming to the same sensory input with excitation from different motivational and reinforcement systems.     

Spontaneous recovery of precise movement and of the postural fixation of the extremities after excision of the somatosensory cortex in dogs

The extirpation of the foreleg area in the somatosensory cortex (SI) in dogs was performed in order to study the role of this area in motor control of the corresponding limb. Stable precise avoidance and escape reactions were established before the cortical lesion. Avoidance reactions disappeared during the first week after the surgery but then they were gradually restored without retraining. At the third weak there was a practically complete recovery of the precision of movements, the ability to fix the leg position and of the duration of successive phases of the reactions. The conclusion was drawn that the initial disturbances of avoidance reactions were most likely the result of diaschisis (shock). The initial disturbances of visually guided instrumental movements and escape reactions were much weaker than those of avoidance reactions (lifting of the foreleg in response to conditioned signal).     

Fromation of forward and reverse connections during elaboration of a classical and instrumental acid-defense conditioned reflex

During elaboration of a classical acid defensive conditioned reflex to passive lifting of a foreleg in dogs, the reinforcing stimulus--acid elicited an extension of the leg via backward connection. At the initial stage of elaboration of an instrumental avoidance reflex, the reinforcing stimulus called forth an extension of the leg, whereas at the stage of a stable reflex it produced a flexion.     

The effect of GABA derivative phenibut on defensive conditioning and internal inhibition

Waking noncurarized rabbits were subjected to defensive conditioning. Subcutaneous injections of GABA derivative conditioning. Subcutaneous injections of GABA derivative Phenibut (nootropic) (40 mg/kg) were shown to accelerate the acquisition of internal inhibition, to decrease and stabilize the time of intersignal reactions, to increase the heart rate, and to decrease the respiration rate. At the early stage of conditioning, Phenibut facilitated movements in response to a conditioned stimulus. Consequently, when using nootropics for normalization and improvement of the CNS operation, one should take into account their effects not only on excitation but also on inhibition in the CNS, as well not only on cognitive processes but also on the somatic state. The findings confirm the involvement of GBABergic neurotransmitter system in the internal inhibitory conditioning.     

The dynamics of the rats higher nervous activity disturbances after total influence of electrons and gamma-rays in doses 5-100 Gy

The dynamics of using of stabilized motor defensive conditioned reflex of active avoidance in "shuttle-box" in rats after total influence of high energy electrons and of gamma-rays in doses 5-100 Gy were investigated. The quality structure of higher nervous activity disturbances after the influence of these kinds of ionizing radiation was identical. Therefore the tendency to disturbances aggravating after the electron radiation influence in the periods of the initial depression and of relatively normalization was revealed, especially after the irradiation in dose 50 Gy. The effective compensation of the functional disturbances in the central nervous system at the first 5-10 min after irradiation was after influence of electron radiation in doses about 30 Gy and after the influence of gamma-radiation in doses about 50 Gy. The irradiation of rats in doses 10 Gy and 5 Gy caused qualitative different dynamics of radiation disturbances in rats higher nervous activity. The differences in rats higher nervous activity after influence of electron and of gamma-radiation in these doses did not manifest distinctly.     

Dynamics of evoked potentials in cortical projection structures during a retarded instrumental defense reflex in dogs]

Evoked potentials (EP) in the somatosensory and auditory cortical areas were studied in four dogs against the background of a retarded defensive instrumental conditioned reflex to clicks. Four phases of the reflex were singled out by the changes in the structure of EP late components (LC) in the two projection zones. The most complex LC changes in the form of intensified negative components and the appearance of additional negative LC are recorded in response to the first click of the series and to the one followed by the conditioned motor reaction (CMR). Against the background of CMR delay, the EPs increased, while during the CMR, they decreased, owing to the diminished negative components, while the positive components were preserved and sometimes intensified. An assumption has been made that cortical projection structures of paired stimuli function in one and the same regime.