[Intralimbic evoked potentials and excitatory cycles under conditions of food and defensive motivations in dogs].
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Animals↗
Biomedical subjects
L I Chilingarian
Publications and source records attributed to L I Chilingarian.
[Steady potential level and afterdischarges arising in response to rhythmic electric stimulation of the dog cerebral cortex].
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Animals↗
[The typological characteristics of higher nervous activity in dogs and the maxima of the cross-correlation function between the electrical activities of the frontal cortex and the brain limbic systems].
Electrical activity of the frontal cortex, dorsal hippocampus, basolateral amygdala and lateral hypothalamus was recorded in eight dogs with chronically implanted electrodes. Mean values of the maxima of crosscorrelation function (MCCF) between electrical potentials in the theta, alpha and beta-2 ranges were used as a basis for assessment of conditions for interaction between these structures. Typological features of the higher nervous activity were assessed by the animal performance under conditions of free choice of the reinforcement mode of a conditioned stimulus: either high probable but of low alimentary quality or with low probability but more valuable. The mean MCCF values in the theta range were higher than in the other ranges. The brain structure which had the high MCCF in the theta-range, at least, with two of the structures under study was considered as "dominant". It was shown that hippocampus was the dominant structure for melancholic dogs, the frontal cortex was in phlegmatics. The hypothalamus was shown to be the "dominant structure" in both sanguine and choleric animals, but, for the most part, its activity was correlated with different structures. Thus, conditions for interaction between the frontal cortex, hippocampus, amygdala and hypothalamus seem to be an important factor, which determines typological features of the higher nervous activity of dogs.
Acoustic Stimulation↗
[I. P. Pavlov's theory on higher nervous activity: the landmarks and trends in its development].
The theory of higher nervous activity created in Pavlovian time is compared with the present-day state of the theory developing due to appearance of new methods, techniques, facts, and concepts. Three principles of Pavlovian theory: determinism; analysis and synthesis; structural approach, as well s types of conditioned reflexes and techniques, types of higher nervous activity, and inhibition problems are discussed. The theory of higher nervous activity is schematically depicted as a tree, some branches of which are presented by facts and concepts obtained and introduced by I.P. Pavlov and his followers during his life, the others are formed by new facts and concepts advancing the theory. What is obsolete in the theory, what are the most prominent tendencies of its development and its new branches are discussed.
Animals↗
[Individual typological characteristics of higher nervous performance and asymmetry of hippocampus and amygdala electrical activity in dogs].
Electrical activity of the frontal cortex, dorsal hippocampus, basolateral amygdala and lateral hypothalamus of both hemispheres was recorded in nine dogs in the state of quiet wakefulness without any stimulation. Individual typological features of higher nervous activity were assessed by the animal performance under conditions of free choice of the reinforcement mode: either high probable but of low alimentary quality, or with low probability but more valuable. Mean values of the maxima of crosscorrelation function between electrical activity of the investigated structures of two hemispheres were used as a basis for assessment of conditions for interaction between left and right formations. For the hippocampus and amygdala, in some dogs these conditions were the best in the theta and beta 2 ranges, in other animals--in the theta and alpha bands. In phlegmatic dogs, spectral densities in the theta range were higher in the left hippocampus than in the symmetrical structure, in sanguine animals spectral densities in the theta and beta 2 ranges in the hippocampus and amygdala were higher in the right hemisphere than in the left one. Thus, the hemispheric asymmetry of electrical activity of the limbic formations seems to be an important factor, which determines the individual typological features of the higher nervous activity in dogs.
Amygdala↗
[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.
Animals↗
[Direct cortical responses to electric stimulation with different frequencies in chronic experiments on dogs].
Direct cortical responses (DCR) to a series of electrical stimuli with a frequency of I to 50 per second with 10 to 20 pulses in each series were studied in chronic experiments on dogs. The nature of cortical responses differed, depending on stimulation parameters. As the stimulation frequency increased, the amplitude and number of late DCR components decreased, and with further increase of frequency, the early components decreased as well. The following types of responses were revealed: recruiting, intermittent and decremental. As the stimulation frequency increased all the three types of responses could be obtained in one and the same cortical point. Recruiting was not typical of high-amplitude and multi-component DCR with a long phase of depression of initial negativity and slightly pronounced short-term subsequent facilitation, while the intermittent type of response appeared at lower frequencies than in other dogs (5 to 10 per sec). A decremental type of response was observed in all the dogs at a stimulation frequency higher than 30 per sec. The duration of the series of after-discharges to a burst of electrical pulses depended on the pattern of the DCR to a single stimulus and on the intensity and frequency of stimulation. With similar parameters of stimulation, the greater the amplitude and the longer the duration of the slow negative DCR wave, the longer the period of after-discharges following a series of stimuli.
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↗
[A collector of evoked potentials].
The collector is an adaptive algorithm for pattern recognition. It proposes new in-line fully-automatic technique to learn and recognize effective patterns of input data stream. Evoked potentials (EP) were recorded by ADDA 100 KHz, 4 channels, and described by 200 points per each EP. The collector recognized different studies of conditioned response (CR) by patterns of EPs in amygdalar central nucleus. In dogs with implanted into the limbic structures concentric electrodes an instrumental CR was elaborated to electrical stimulation of the dorsal hippocampus. Generalization or transfer of this CR was tested by means of electrostimulation of amygdalar basal nucleus. The generalization in the first experiment took place approximately in 86% of cases, in the second one in 52% of cases. In the first experiment the amplitudes of initial negativity and of late positive waves were smaller than those in the second one and in the experiments before conditioning.
Algorithms↗
[The contribution of Academician L. A. Orbeli to the theory of higher nervous activity].
In the paper are discussed the main directions of the investigation of the higher nervous activity, fruitfully developed by academician L. A. Orbeli and his school. These directions are the following: the evolutionary approach, the study of the influence of the sympathetic nervous and endocrine systems, of the role of the extracortical brain structures, especially the hypothalamus and the cerebellum, and the significance of pain and efferent systems for the higher nervous activity.
Animals↗
[Choice between probability and value of alimentary reinforcement as means for revealing individual typological features of dog behavior].
Individual typological features of behavior of dogs were investigated by the method of choice between the low-valuable food available constantly and food of high quality presented with low probability. Animals were subjected to instrumental conditioning with the same conditioned stimuli but different types of reinforcement. Depression of a white pedal was always reinforced with meat-bread-crumb mixture, depression of a black pedal was reinforced with two pieces of liver (with probabilities of 100, 40, 33, 20, or 0%). The choice of reinforcement depended on probability of valuable food and individual typological features of the nervous system of a dog. Decreasing the probability of the reinforcement value to 40-20% revealed differences in behavior of dogs. Dogs of the first group, presumably with the weak type of the nervous system, more frequently pressed the white pedal (always reinforced) than the black pedal thus "avoiding a situation of risk" to receive an empty cup. They displayed symptoms of neurosis: whimper, refusals of food or of the choice of reinforcement, and obtrusive movements. Dogs of the second group, presumably with the strong type of the nervous system, more frequently pressed the black pedal (more valuable food) for the low-probability reward until they obtained the valuable food. They did not show neurosis symptoms and were not afraid of "situation of risk". A decrease in probability of the valuable reinforcement increased a percentage of long-latency depressions of pedals. It can be probably suggested that this phenomenon was associated with increasing involvement of cognitive processes, when contributions of the assessments of probability and value of the reinforcement to decision making became approximately equal. Choice between the probability and value of alimentary reinforcement is a good method for revealing individual typological features of dogs.
Animals↗
[Individual typological features of the dog behavior during the choice between food and avoidance of electrocutaneous stimulation].
Two conditioned reflexes (CR) on flash were elaborated in five dogs in three experimental series. In one of them pressing on pedal were constantly reinforced with two pieces of liver, in other--escape or avoidance of skin stimulation with lifting of leg. In a third series, series of reinforcement choice, in front of animal with electrodes, fasting on leg, put the pedal. During of choice series defensive reactions were dominated in two dogs, alimentary reactions--three of them. For restoration alimentary behaviour in dog with great dominating of defensive reactions were many times reinforced with--food "passive" pressing legs on pedal during conditional stimuli, dog with less dominating of these reactions for restoration were enough a few coupling of conditional stimuli with food. With intensification electrocutaneus stimulation of legs or decreasing alimentary reinforcement we a success of diminishing of degree of alimentary reaction domination in one dog and in other ones temporarily changed of these domination on prevalence of defensive reactions. The results were compared with data, obtained in these dogs with technique of choice between probability and value of alimentary reinforcement. This comparison were permitted us of ranging dogs on scale "carefulness-riskiness", revealed of individual typological features of these animals.
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↗
[Features of differential inhibition in choice between alimentary and defensive response].
Instrumental defensive (avoidance/escape) and alimentary responses (reinforced with palatable food) in dogs were conditioned by the same stimulus (6-Hz light flashes). Differential inhibition for these responses (0.6-Hz flashes) was formed in unalterable series. Later on, alternative experiments with choice between reinforcements were carried out. In both of experimental series, the degree of alimentary excitability (hunger, satiation) was changed. Numbers of responses to differential and positive conditioned stimuli and their latencies were calculated. Under condition of choice (electrodes on a leg and a pedal in front of a dog) the response depended on a dominant motivation. The dogs differed in the degree of motivation dominance. Differential inhibition was less perfect in unalterable experimental series with dominant motivation. Under conditions of choice between alimentary and defensive reinforcements, the response to the differential stimuli depended on the balance between these motivations: two days of hunger increased the number of alimentary responses, defensive responses prevailed after satiation.
Animals↗
[The role of the basal ganglia in the reproducibility of instrumental reactions acquired to electrostimulation of the hippocampus].
In dogs with electrodes implanted into the brain, a defensive instrumental conditioned reflex (CR) was elaborated to light flashes, stimulation of the dorsal hippocampus (DH) and caudate nucleus (CN) stimulation. Reproducibility of the learned movement was tested for the contralateral DN, CN, nucleus accumbens (AN) and pallid globe (PG). In the second series the percent of the elicited movements was compared to EPs, appearing in response to signal and testing stimulation. The degree was elucidated of structures participation in motivational, signal and executive links of CR. Low degree of AN participation in the executive CR link (2-nd series) and a high degree of AN and PG participation in the signal link (3-d series) were shown. Thus, intrasystemic CR generalization was more effective than the intersystemic one.
Animals↗
[The role of signal and motivational links of a conditioned reflex in the initiation of instrumental movements in dogs].
Alimentary instrumental conditioned reflex (CR) was elaborated in dogs to light flashes (I series), electrostimulation (ES) of the hippocampus (II series) and the hypothalamus (III series). Nonreinforced ES of the hypothalamus, amygdala, hippocampus and septum reproduced pressings on the pedal to the least extent in the I series (17-40% of trials), increasing in the II-nd one up to 40-87% during stimulation of the lateral hypothalamus, medial amygdala and contralateral hippocampus. In the III-rd series the number of pressings increased statistically significantly in comparison with the I-st series for most structures. Probably, besides the artificial increase of motivation during ES of the limbic structures which took place in all series, in the II-nd and III-rd series significance for movement reproduction was acquired by CR generalization appearing due to close interconnection of the structures. In this phenomenon connections (evaluated by the EPs) from the tested structures to the initially signal one are important.
Animals↗
[Dependence of the electrical activity of the amygdaloid complex on motivation level and emotional status in the dog].
On the basis of spectral analysis of prolonged realizations (hundreds of seconds) of electrosubcorticograms of the amygdalar complexes of three dogs, the effect of increase in power of amygdalar rhythmic activity was found, at the change of motivation level in conditions of dominance of alimentary or defensive motivation independently of its kind. Resonance characteristics of the system responsible for the generation of the given rhythm remain unchanged; this allows to explain the increase of the spectral peak by the rise of the inflow of afferent impulse activity to the amygdala. At presence of competitive motivations no summation of their influences is observed; a more complex effect on the rhythm arises in the amygdala.
Amygdala↗
[Mechanism of the generalization of a conditioned reflex elaborated to electrostimulation of the brain in dogs].
To study functional connections in the limbic system (LS), a model was used of instrumental alimentary CR, elaborated in response to low-frequency hippocampus electrostimulation with testing of its generalization within the LS. The dependence was established of the generalization on activation of corresponding pathways between the signal and tested brain structures, the activation of pathways was estimated by EPs recorded in limbic structures in response to hippocampus stimulation (during CR performance), or vice versa (in generalization trials). It turned out that for the appearance of CR generalization, two-way connections between signal and tested brain structures or connections only to the signal structure are more important. One-way connections from the signal structure to tested ones, judging by data, are not important for appearance of the CR generalization in used model of conditioning.
Animals↗