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PubMedDate not supplied

Participation of the amygdaloid complex in conditioned reflex learning in dogs.

The features of the formation of conditioned alimentary reflexes in response to the stimulation of the basolateral division of the amygdaloid complex with an electrical current at a frequency of 50 pulses per second were studied in five dogs. The possibility of the development of differential inhibition in response to unreinforced stimulation of the same structures of the amygdaloid complex with a current at a frequency of 5 pulses per second was demonstrated. The rate of formation of positive and inhibitory conditioned reflex reactions, their quantitative characteristics, and the depth of differential inhibition in response to stimulation of the amygdaloid complex is greater than those found with the use of acoustic stimuli in the same dogs. Comparison of the rate and dynamics of the process of conditioning of two structures belonging to different levels of nervous integration, namely, the limbic (the amygdaloid complex) and the striatal (the caudate nucleus), carried out under the same experimental conditions, indicates that activation of the nervous elements of the limbic formation acquires signal significance significantly more rapidly than in the case of the caudate nucleus.

Acoustic Stimulation↗
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[The conditioned reflex behavior of dogs to the intracaudate administration of corticoliberin].

Situational conditioned reflexes in dogs were studied before and after intracaudate bilateral microinjections of corticoliberin (CRF). Intracaudate microinjections led to an enhancement of locomotor activity, the restoration of earlier extinct exploratory behaviour, impairment of differentiation inhibition, changes of emotional reactions. Behavioural changes were accompanied by shifts of cortisol, vasopressin, norepinephrine and adrenalin levels in blood of experimental animals. The maximal impairment of conditioned behaviour was observed 30 min after CRF microinjections and coincided with maximal activation of pituitary-adrenocortical system. On the basis of the data obtained we conclude that CRF-sensitive systems of the neostriatum participate in the mechanisms, underlying behavioural, vegetative and hormonal changes.

Animals↗
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[Participation of the amygdala in the formation of heterogeneous conditioned reflexes].

Characteristics were studied in the same dogs of the formation of conditioned reflexes to signals reinforced by biologically different stimuli--food, acid and current and of differentiations to them, after amygdala ablation. Amygdalectomy leads to the disturbance of the conditioning process, independently of the biological significance of the reinforcement. However, the deepest and the most prolonged disturbances occur in the system of alimentary behaviour and in elaboration of more complicated instrumental defensive reflexes in which current avoidance requires not only lifting of the paw but also retaining at a definite height for a certain time. Amygdala ablation considerably impedes the process of differentiation of positive and inhibitory stimuli leading to a disturbance of correct evaluation of signal significance and to inadequate behavioural reactions.

Amygdala↗
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[Relation between the level of conditioned reflex activity and concentration of serotonin in the blood of normal and neurotic dogs].

Higher nervous activity of dogs was studied using Pavlovian method of alimentary salivary conditioned reflexes. Serotonin (5- hydroxytryptamine) content in the venous blood was defined by means of fluorescent spectrofluorimeter using orthophthalic dialdehyde. A high level of conditioned and unconditioned reflexes was accompanied by a low serotonin blood content, while a low level of reflexes was accompanied by a high serotonin content. Negative correlation is supposed to exist between the degree of activation of nervous processes and blood serotonin content. Blood serotonin content increased in dogs in experimental neurosis with expressed reduction of the level on alimentary conditioned and unconditioned reflexes.

Animals↗
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[Discriminative and extinctive inhibition of alimentary conditioned reflexes against a background of electric stimulation of the parietal cortex].

Changes in differentiation and extinction inhibition of alimentary secretory conditioned reflexes during electrical stimulation of parietal cortical zones with a weak subthreshold current of 1 to 100 imp/s frequency were studied in dogs with electrodes implanted in the cerebral cortex. It was found that stimulation of these associative cortical areas results in disinhibition of differentiation inhibition. The depth of the disturbance depends on the frequency of the stimulating current: with high frequency stimulation, the effects of disinhibition are much more pronounced. Extinction of the conditioned alimentary reflex to an acoustic stimulus during stimulation is also impeded and is accompanied by motor alimentary excitation, particularly when the parietal cortex is stimulated by the high-frequency current.

Animals↗
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[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↗
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[The over-reinforced conditioned reflex--a highly adaptive behavioral system].

Specialized (according to Pavlov) instrumental alimentary conditioned reflexes (CR) were studied after extremely prolonged training (2500-3000 pairings). It was established that these CR were characterized by extremely rapid extinction (till 15-20 absences of instrumental reaction after only 2-7 presentations of non-reinforced conditioned stimulus, despite the classical statement on difficult extinction of consolidated CR) independently of typological features and level of alimentary motivation of animals. The results obtained allow us to set aside such reflexes as a special category of CR which are underlined by neurophysiological and neurochemical mechanisms distinct from those of commonly used in experimental practice less trained CR. The phenomenon described may be interesting in studying the processes of learning and long-term memory.

Acoustic Stimulation↗
PubMed2006

The role of motivation in the performance of conditioned reflex switching of a maze skill in response to substitution of food reward quality in ants of the species Myrmica rubra.

The characteristics of learning in ants - active Myrmica rubra foragers - were studied in a maze at different levels of colony carbohydrate food need with reinforcement consisting of carbohydrate (sugar syrup) or protein (pupae of Lasius niger ants). Measures of the maze skill during learning reinforced with syrup were somewhat worse than those during learning reinforced with pupae, especially in terms of time-based measures. Ants were able to modify the acquired conditioned reflex reaction when the quality of reinforcement changed. At high levels of food need (" hungry" colony), substitution of syrup with larvae and vice versa was followed by transformation of the previously formed skill; this occurred at both experimental periods (training and testing). At low levels of motivation ("sated colony"), the optimized maze habit formed with protein reinforcement was replaced in the test with carbohydrate reinforcement by a "stochastic," unoptimized behavior with a dominance of investigative activity. These experiments demonstrated that conditioned reflex switching can occur in higher social insects - ants - in which the different forms depend on the level of colony need for food and, respectively, on the level of social food-related motivation of forager ants. The special importance of using the switch activating the corresponding motivational system before changing the reinforcement food quality is emphasized.

Animals↗
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[Shifts in steady potential levels and changes in the cerebral bioelectrochemical potential during orientation and conditioned reflexes in rabbits].

The shifts of the steady potential level (SPL), recorded with non-polarized electrodes, and the changes in bioelectrochemical potential (BEChPs), recorded with platinum electrodes, were led from the rabbit brain surface in chronic experiments. The stimuli, that were new for the animal, caused only SPL shifts (0.1-0.3 mv), BEChPs showing no changes. BEChPs changed (by tenths to several millivolts) only in the process of the conditioned reflex formation, during the pairing of the conditioned and reinforcing stimuli, during which the shifts of SPL were also observed (up to 0.5-1 mv), different from the ones during the orienting reflex. Simultaneous recording of the SPL shifts and the changes in BEChPs showed that these phenomena are external manifestations of independent processes. It is suggested that the brain activity involved in the perception and the analysis of the informational value of a new stimulus, is connected with bioelectrical processes, rather than with the metabolic ones. During the formation of the defensive conditioned reflex, along with the enhancing of the activity connected with bioelectrical processes, other type of activity appears which is accompanied with considerable metabolic shifts.

Animals↗
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[Dynamics of elaboration of a conditioned reflex and differentiations in the snail].

It is shown that dynamics of percentage of conditioned food refusals by snails Helix pomatia and Helix lucorum is satisfactorily approximated by regression equation of exponential type with included coefficient reflecting the animals state before the beginning of learning. The ability is established of the snails to practically completely differentiate various alimentary conditioned stimuli. The introduction of differentiation always improved the reflex consolidation. Conditioned reactions to differentiation stimulus appeared at the elaboration stage and were absent at the stage of conditioned reflex consolidation.

Animals↗
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[Electroencephalographic analysis of a conditioned reflex to time].

EEG parameters in different cortical territories of free moving dogs were analyzed during formation of conditioned reflex to time, in situation of instrumental alimentary conditioning. It was shown that in organization of a reflex to time as a complex reaction(present, trace and rhythmic processes), different brain systems play different roles in the formation of its stages. Sensory systems provide for the complex of trace processes underlying reaction to time. Associative structures are involved in the afferent synthesis necessary for the present moment. Integrative-triggering formations attach formed reaction to a strictly fixed time.

Animals↗
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[Conditioned reflex changes in the functional connections between adjacent and remote cortical neurons].

A motor conditioned reflex to sound was elaborated in cats with electrodes (nichrome wire dia 50 mcm) chronically implanted in the auditory cortex. Multineuronal activity preceding by 30 s the conditioned signal was analysed. Impulse activity of two to three neurones was isolated from every record by means of an amplitude discriminator. Dependence between impulse series isolated either from one record or from records obtained with two electrodes placed at a distance of up to 200 mcm from one another, was estimated by crossover interval histograms. Consequently functional connections between neurones were defined by the dependence of impulse series. In the process of conditioning dynamic reorganization of interneuronal connections was revealed. With a stable reflex, the number of connections both between neurons in the microregion and between neurones of neighbouring microregions considerably increased due to an increased number of excitatory connections. After extinction of the reflex, the number of connections between adjacent neurons increased still more, though due to enhancement of the inhibitory type connections. Nonetheless, excitatory connections kept dominating. At the same time, the number of connections between neurons of the neighbouring microsystems sharply decreased.

Animals↗
PubMedDate not supplied

[Formation of systems of unilateral conditioned reflexes following section of the rostral portion of the corpus callosum].

Unilateral conditioned reflexes and two-link reflex systems with regular rhythmic alternation of positive and inhibitory reflexes were elaborated by Abuladze method in four dogs with a preliminarily dissected rostral part of the callosal body. Whereas the rate of formation of simple unilateral positive reflexes did not differ from that of reflex formation in intact animals, the formation of two-link unilateral systems proved to be disturbed. In spite of considerable stabilization of positive and inhibitory reflexes, ultraparadoxical relations were revealed when the same stimuli were applied in the system which testified to the disturbance of the after-effect dynamics. It has been assumed that rostral parts of the callosal body take part in the fixation of traces as the first component of the memory mechanism.

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