Alimentary Conditioned Reflexes Research Articles

Superconsolidated conditioned reflex--a highly adaptive system of behavior.

Superconsolidated (2500-3000 combinations), long-trained (two to three years), specialized (per I.P. Pavlov), instrumental alimentary conditioned reflexes were investigated in cats. It was demonstrated that such conditioned reflexes are unusually rapidly extinguished, despite the classical notion of extinction, according to which the more consolidated the conditioned reflex the more difficult it is and the longer it takes to extinguish it. Thus, in the very first experiment, stable extinction of the conditioned reflex commenced after two to seven (in different animals) presentations of the conditional stimulus without reinforcement, and 15-20 "zeros" in a row in relation to the conditioned reaction could be obtained. The rate of extinction essentially did not depend on the individual features of the animals or the level of alimentary motivation. The data obtained make it possible to set such reflexes apart in a special new category of conditioned reflexes, which apparently have a different neurophysiological and structural control base than the "younger" conditioned reflexes commonly studied in the laboratory.

Analysis of the caudatoventrotegmental influences during the realization of the motor alimentary conditioned reflexes.

Analysis of the caudatoventrotegmental influences during the realization of the motor alimentary conditioned reflexes.

Study by nontraditional analytic methods of features of cortical potentials, taking high-frequency components into account, in dogs during instrumental learning.

A new method has been developed for the coding of EEG tracings which is an alternative to the classical spectral correlation analysis. This method has made it possible to compensate to a considerable degree for limitations which are unavoidable with the Fourier transform, and to obtain additional information regarding the form of the tracing, which reflects the fluctuations of brain potentials. The new system that has been presented for coding the EEG is, in our view, the most adequate (of the methods known to us) for identifying the individual features of the EEG, in terms of evaluating both their regional differences and similarities. The data obtained convince us once again of the real existence of high-frequency low-power components of the EEG, and their enhancement during instrumental learning in dogs (motor alimentary conditioned reflexes). In addition, data have been obtained pointing to the intensification in some regions of a slow-wave constituent; this has not been observed previously in carrying out a Fourier transform.

The influence on the realization of alimentary conditioned reflexes of the chronic injection of leu-enkephalin and its analog tetrapeptide into the caudate nucleus of dogs.

The influence on the realization of alimentary conditioned reflexes of the chronic injection of leu-enkephalin and its analog tetrapeptide into the caudate nucleus of dogs.

A computer analysis of EEG-intersignal reactions during the development of motoric alimentary conditioned reflexes in dogs.

The background electrical activity of the neocortex in the interstimulus periods at the stage of generalization during the development of alimentary motor conditioned reflexes (CR) in dogs was the investigational object. It was characterized by the appearance of brief (0.1-0.3 sec) trains of high frequencies (HF), significantly exceeding the adjacent initial baseline in frequency and amplitude. The relative variance index which we had developed made it possible to distinguish this EEG phenomenon in the initial realizations of the background activity when they were inputted into a digital computer. It was not possible to evaluate the parameters of the HF chains by means of a spectral correlation analysis. Nonstandard techniques of computer analysis directed toward the decomposition of the EEG tracing into a system of oscillations and toward the obtaining of the corresponding amplitude-frequency distributions (maps) were developed by us for the purpose of accomplishing this objective. It was demonstrated that HF trains were localized in these maps in specific, quite compact regions.

Intralimbic evoked potentials during the formation of an alimentary conditioned reflex in response to the electrostimulation of the hippocampus of dogs.

Instrumental alimentary conditioned reflexes (CR) in response to the electrostimulation of the hippocampus were developed in experiments on dogs with electrodes implanted in various divisions of the hippocampus, the amygdala, the septum, and the hypothalamus. During their development the evoked potentials (EP) were investigated in the hippocampus itself and in other limbic structures, as well as in the hippocampus during the testing of the latter for the purpose of verifying generalization. The formation and extinction of the CR was accompanied by changes in the amplitude-temporal characteristics primarily of late components of the EP picked up from the lateral hypothalamus and the amygdaloid complex in response to the hippocampal electrostimulation. During the carrying out of this stimulation of signal functions (pedal pressing to obtain food), the average amplitude of the trace positivity and of the late negative wave were found to be lower than by the end of extinction in the presence of ineffectiveness of the signal. The average amplitudes of the late components of the hippocampal EP which arose in response to electrostimulation of the amygdala were lower in those tests in which the instrumental movement appeared when the generalization of the CR was tested.

Organization of network properties of cells in local and distributed neuronal networks of the brain of cats.

The network properties of neurons of the visual and motor cortex and of the lateral nucleus of the hypothalamus were investigated on the basis of identified interneuronal interactions, using the cross-correlation method of analysis, in cats with developed alimentary conditioned instrumental reflexes to light. The varied organization of the network properties of cortical neurons in the organization of local and distributed neuronal networks was demonstrated, namely: the predominance of divergent properties over convergent properties for large cells in local networks and the leveling out of these relationships in distributed networks. The neurons of the lateral nucleus of the hypothalamus had an equal representation of convergent and divergent properties in the organization of local and distributed networks. The network properties of neurons of the cortical and subcortical structures were manifested in the background, following the development of conditioned reflexes, and during extinction. Only the small cells of the visual cortex were functionally dependent and changed the relationship of network properties in local networks during the extinction of conditioned reflexes.

Functional role of the neurospecific S-100 protein in the processes of memory.

The change in the content of S-100 protein in the brain in the presence of learning and an amnestic influence (administration of an M-cholinolytic), taking interhemispheric asymmetry into account, was studied in experiments on white rats. The action of S-100 protein and of an antiserum to this protein on the learned behavior of the rats were also investigated. It was established that the level of S-100 protein increases in the left and right hemispheres in the process of the development of an alimentary conditioned reflex. The disruption induced by the cholinolytic of the processes of the development of conditioned reflexes is accompanied by a decrease in the content of S-100 protein in the brain. Intracisternal administration of an M-cholinolytic and an antiserum to S-100 protein mutually potentiates their amnestic effect.

Participation of glutamatergic and dopaminergic systems of the neostriatum in the organization of alimentary conditioned reflexes.

In this study the results of behavioral, neurophysiological, and morphological investigations in relation to the participation of the corticostriatonigral system in the organization of conditioned reflexes are presented. It was demonstrated in experiments on dogs that blockade of N-methyl-D-aspartate receptors of the caudate nucleus disrupts the realization of consolidated conditioned reflexes and renders their development more difficult. The blockade of quisqualate receptors facilitates the process of differentiation. Switching off of the dopaminergic input makes the development of positive conditioned reflexes more difficult. The reversible switching off of the substantia nigra leads to the reorganization of the neuronal activity of the caudate nucleus in response to the presentation of the conditional signal. Inhibitory nigral influences are directed primarily to the ventromedial divisions of the nucleus, while activating influences are directed to its dorsal segments. The topically organized connections of the motor regions of the cortex with the dorsal region of the caudate nucleus, and of the limbic regions with its ventromedial divisions were studied in morphological investigations on cats. A certain distinctiveness was identified of the spatial organization of the nigrostriatal projections. The data obtained are discussed from the point of view from the systemic organization of behavior.

Comparative psychological approach to the analysis of the functions of the hippocampus

As compared with dogs, the development of conditioned reflex switching-over of heterogeneous conditioned reflexes in intact rats is often accompanied by the development of reactions of the neurotic type. Experiments involving injury of the hippocampus (in rats) and the recording of electrical activity (in dogs) showed that this structure participates in the formation of conditioned reflex switching-over of instrumental reflexes. Following the injury to the hippocampus, the rats successfully formed the switch-over. The switch-over signal altered the electrical activity of the hippocampus in the dogs. Consequently, the hippocampus in both species of animals belongs to the system of structures which participate in the formation of conditioned reflex switching-over. Hippocampectomized rats were not capable of developing an alimentary conditioned reflex at the 30% level of reinforcement. The highest values of the frequency of the hippocampal theta rhythm were obtained in the dogs at just this level of probability of reinforcement. These data indicate that the assurance of reactions to signals with a low probability of reinforcement is an important function of the hippocampus in various species of animals.

The participation of mediator and peptidergic systems of the brain in conditioned reflex mechanisms

New data on the significance of mediator and peptidergic systems of the striatal level in the organization of alimentary conditioned reflexes are presented in this report. The role of acetylcholine-, dopamine-, GABA-and P-ergic systems of the caudate nucleus and the amygdala in the realization of positive and negative conditioned reflexes was investigated. The experiments were carried out on dogs with chemotrodes and microelectrodes implanted in subcortical structures. The results of the experiments with microinjections of the relevant substances into individual subcortical structures showed that activation of the same mediator system in various structures may lead to both unidirectional and multidirectional behavioral effects. On the other hand, the activation of various subcortical mediator systems can lead to identical changes in conditioned reflex activity. The effect of the administration of activators or blockers of a subcortical mediator system depends in many ways on the functional state of the nervous system at the moment of administration and on the localization of the microinjection. It is difficult to predict beforehand the role of various subcortical structures in the organization of integrated behavioral acts. The question of the necessity of studying mediator and peptidergic systems of each subcortical structure in order to understand their significance in the mechanisms of the conditioned reflex is raised.

Influence of extirpation of the sensorimotor area of the cortex on the formation of conditioned reflexes in response to a complex signal in the ontogenesis of the cat

The influence of the extirpation of the sensorimotor cortex (SMC) on the formation and maintenance of a previously developed alimentary conditioned reflex to a simultaneous complex stimulus (light + sound) with extinction of the reaction to unreinforced components of the complex signal was studied in kittens aged 39 days to 4 months. The extirpation of the SMC prior to 2.5 months of age had no influence on either the formation or maintenance of the conditioned reflex to the complex signal developed prior to the operation. The extirpation of the SMC in preliminarily trained kittens aged 3.5 months and older leads to disinhibition of the differential components when the positive conditioned reflex to the complex signal is maintained. In untrained kittens of the same age the extirpation of the SMC was manifested in the animals' incapacity to inhibit the motoric reaction to the differential signal. The question of the role of the SMC in ontogenesis during the formation of adequate forms of behavior which require the achievement of intersensory interactions is discussed.

Alimentary conditioned reflexes in dogs on activation and blockage of the cholinoreactive amygdaloid system.

1. Chemical stimulation of the basolateral area of the amygdala by acetylcholine at a dose of 300 μg, carbocholine at a dose of 0.5 μg, and atropine at a dose of 60 μg changes the production of the secretory component of alimentary reactions but has no effect on the production of the instrumental component. 2. Activation of the cholinoreactive system of the amygdaloid complex in dogs has an inhibiting action and blockage an activating action on the production of alimentary secretory conditioned reflexes; in the case of a decrease in the value of the total conditioned reflex salivation, differentiation is improved, while in the case of an increase in this value it is impaired. 3. On blockage and activation of the cholinoreactive system of the basolateral area of the amygdala, the ratio of the conditioned reflex salivation in response to different stimuli presented in a stereotype order (dynamic stereotype) changes.

Conditioned reflex changes in relations between afferent inputs from the lateral geniculate body and pulvinar in the cat visual and association cortex.

1. An alimentary instrumental conditioned reflex to electrical stimulation of the lateral geniculate body and pulvinar (LGB and P) can be formed, extinguished, and restored irrespective of whether the LGB + P or P + LGB combinations of stimuli is used. 2. If LGB is stimulated 40 msec beforehand, facilitation of the response in VC and AC to testing stimulation of P, observed in untrained cats, is inhibited when the reflex to stimulation of LGB + P is consolidated; moreover, a considerable increase in amplitude of the response to conditioning stimulation of LGB, takes place. 3. If P is stimulated 40 msec before LGB during conditioning to stimulation by the P + LGB combination, in the middle of training facilitation of the response to testing stimulation of LGB is observed in both VC and AC, with a simultaneous increase in amplitude of the response to conditioning stimulation of P, although these changes are not found when the reflex is consolidated. 4. During perception of a monomodal complex conditioned stimulus relations between individual cortical inputs are modified within the same analyzer.

Effect of some intracerebrally administered drugs on a conditioned reflex in the cat

Injection of carbachol into the anterior hypothalamus or thalamus (intralaminar nuclei) in freely-moving cats caused a dose related inhibition of alimentary conditioned reflex performance (CRP). The inhibition directly correlated with the intensity of the emotional (rage) reaction also elicitable by carbachol from these parts of the brain. The inhibition of CRP after intrahypothalamic or intrathalamic carbachol application seemed to be a secondary effect due exclusively to the altered emotional state of the animal. Injection of carbachol into the dorsal or ventral hippocampus as well as the basal or central part of the amygdala also inhibited CRP. This inhibitory effect could only be observed when the EEG pattern of the animals showed local or propagated seizure discharges. Thus the inhibition of CRP after intralimbic carbachol application seemed to be a secondary effect due to pathologic alterations in the electrical activity of the brain. All the above effects of carbachol were easily counteracted by topical pretreatment with a few μg of atropine. Nicotine and noradrenaline were ineffective in all regions investigated.

Functional significance of the hippocampus

The alimentary conditioned reflex to time was manifested in a motor reaction of the unrestrained dog to the food cup. Latencies of responding and running speeds were measured to within hundredths of a second. The conditioned stimuli were presented in a stereotype. Before the lesions the dogs were performing to the time factor alone, i.e. without presentation of the stimuli. Hippocampal lesions resulted in a complete disappearance of the well established conditioned reflexes to time with intervals of 30 sec, 1, 2 and 5 min. In spite of the long training (over two years) the hippocampectomized dogs failed to recover the conditioned reflexes to time. At the same time hippocampal lesions hardly affected the positive conditioned reflexes and discrimination of single and complex conditioned stimuli. The hippocampus appears to be involved both in the mechanisms of remembering the time count and in trace processes underlying memory. Lesions in the parietal cortex and underlying white matter impaired neither reflexes to time, nor those to the stimuli.

Glucose-6-phosphate dehydrogenase activity in the mucosa and musculature of the duodenum and stomach of rats with alimentary-conditioned reflex.

Les résultats obtenus démontrent que les animaux à réflexe conditionné alimentaire présentent, s'ils sont sacrifiés avant l'heure du repas, une augmentation de l'activité de la G-6-PDH dans la muqueuse et la musculature du duodénum et de l'estomac. Quatre heures après l'administration de la ration alimentaire, l'activité de l'enzyme diminue d'environ 75%.

A conditioned reflex study of sensory defects caused by cortical somatosensory ablations

Abstract The learning and retention of an instrumental alimentary conditioned reflex elicited from either hindlimb by reproducible, light tactile stimuli (puffs of air) was studied in relation to the selective removal of the electrophysiologically determined hindlimb portions of cortical areas S I and S II. Ablations were made in one hemisphere at a time. No difference between the sides was observed in the postoperative learning of dogs with unilateral ablations. In preoperatively trained dogs the ablations resulted in transient impairment mainly of the reflexes from the contralateral limb. Ablations were made in the second hemisphere of the preoperatively trained dogs after recovery from the initial ablations and in the second hemisphere of one postoperatively trained dog after complete learning. These ablations also gave transient impairment mainly of the reflexes from the limb contralateral to the latest ablations. The effects of the second ablation were always more severe than those of the initial ablation. None of the effects could be attributed to changes in the motor performance of the conditioned reflex. It is postulated that the removed parts of the somatosensory areas were engaged in the transmission of the sensory impulses en route to elicit the reflex response, either directly as part of the reflex pathway or indirectly through exerting facilitation on the reflex pathway at a distance. The observed contra-and ipsilateral impairments are discussed with regard to quantity and quality in relation to previous studies.

The Influence of Ablation of the Dorsal Section of the Hippocampus on Alimentary Conditioned Reflexes in Cats

At present a great deal of attention is given to questions of the physiological role of the hippocampal formation in the higher nervous activity of animals and man. A sizable number of both experimental and clinical-neurological investigations indicate that the hippocampus plays a definite part in conditioned reflex activity. Both ablation and stimulation produce noticeable alterations (Grastyan [13, 14], Brady [1], Bures et al. [11], Zager et al. [3], Urmancheyeva [9, 10] etc). (1)