The conditioned reflex. A meaningless concept. A conditioned emotional response.
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Conditioning, Classical↗
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Comparative study of the roles of ACTH and beta-endorphin in regulating conditioned reflex activity in the hedgehog.
Data on the relative effects of the neurohormone ACTH1-39 and the opioid peptide beta-endorphin on conditioned reflex activity in the hedgehog are presented. It was demonstrated that administration of ACTH (30-50 micrograms/kg s.c.) led to facilitation of learning and strengthening of memory processes (conditioned reflex traces). ACTH promoted strengthening of movement, orientational-investigative, and intersignal activities, produced hyperalgesia, and blocked the effects of naloxone. Administration of beta-endorphin (30-40 micrograms/kg s.c.) lengthened the latent periods of conditioned reflexes, produced a pronounced analgesic effect, and reduced movement and intersignal activities. The effects of beta-endorphin were eliminated by dosage with naloxone. Administration of beta-endorphin blocked the inhibitor effects of stimulation of the limbic cortex; doses of ACTH produced partial release of inhibitory effects. The differences between the effects of ACTH and beta-endorphin on higher nervous activity are discussed, as are the possible mechanisms of these effects.
Adrenocorticotropic Hormone↗
[Effect of destruction of midbrain raphe nuclei on elaboration and preservation of heterogeneous conditioned reflexes].
The destruction of the midbrain raphe nuclei in rats results in a gradual drop of serotonin content in the brain. Its moderate drop, which setts in on the eighth day after ablation of the raphe nuclei, is not attended with any disturbance in elaboration of motor alimentary and defensive conditioned reflexes, while the retention of motor alimentary conditioned reflexes is sharply deteriorated. After a sharp reduction of serotonin content in the brain, which is observed on the fifteenth day after the operation, the animals lost their capacity to elaborate either motor alimentary or denfensive conditioned reflexes.
Animals↗
[Conditioned reflex salivary and vasomotor reactions in normal conditions and following castration].
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Cardiovascular Physiological Phenomena↗
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.
Animals↗
[EEG correlation and cortical neurons spike activity during elaboration of a defensive conditioned reflex].
Elaboration of electro-defensive conditioned reflex to light in rabbits has shown, that the values of summary cross-correlation coefficients between EEG and impulse activity of cortical neurones do not change significantly as compared to the control. In these conditions does not change either the part of the neurones that have a significant correlation of their impulse discharges with any configuration of the EEG wave. During 6--10 days of conditioning there occurs a decrease in the amplitudes of both positive and negative EEG oscillations, connected with unit discharges in the neocortex. An EEG quantum has being recorded, i. e. a depolarization potential, directly connected with the generation of spikes by the studied nervous elements.
Animals↗
[Age and elaboration of conditioned reflex switching in dogs].
Conditioned switching-over during initial elaboration of either a food-procuring or defensive (two-way shuttle-box avoidance) reflex in the same experimental chamber was studied in one-and-a-half month puppies and adult dogs. In the adult animals, initial learning of both habits proceeded more rapidly than in the puppies. When the defensive habit was elaborated first, subsequent elaboration of the food-procuring reflex in conditions of switching-over was much longer due to a high level of fear. In the puppies, on the contrary, regardless of which of the two habits was elaborated first, duration of the second habit elaboration in conditions of switching-over was considerably shorter. The transfer of experience from one experimental situation to other is apparently facilitated by absence of fear. The data obtained are considered from the viewpoint of the hypothesis on similarity in the behaviour of puppies and adult hippocampectomized dogs.
Age Factors↗
[Participation of midbrain central gray neurons in the organization of defensive conditioned reflexes in the cat].
Neuronal reactions of the periaqueductal gray matter were studied in cats during conditioning defence reflex to auditory stimuli. Phasic and tonic spike responses lasting up to 3s developed in the recorded neurons in response to conditional stimulus. These reactions had developed long before the elaboration of the conditioned reflex and disappeared significantly later than the conditioned reflex became extinct. The generation of the spike response after elaboration of the conditioned reflex took place 100-200 ms before the appearance of the movement evoked by the conditional stimulus. An increase of the tonic discharge of the recorded neurons also preceded the voluntary movements by 100-500 ms. Neuronal responses in the periaqueductal gray matter to differential stimuli could be elaborated with great difficulty; they had the form of group discharges 150-200 ms long. These responses were unstable. On the basis of the obtained data the conditioned reflex is considered as a result of a multilevel hierarchic process of neuronal activity change which begins in unspecific structures of the mesencephalon.
Animals↗
[Conditioned reflex activity of pigeons as affected by an infra-low frequency alternating magnetic field].
In experiments on 35 pigeons formation and realization was studied of alimentary motor conditioned reflexes under the influence of alternating magnetic field (AMF) with a frequency of 5 and 8 Hz and induction 5100 nTl. It has been found that under the action of such AMF, the percent of adequate responses lowers and the time of motor reaction during execution of motor alimentary conditioned reflexes and of delayed reactions increases. Realization of delayed reactions is disturbed more significantly than that of the present conditioned reflexes. AMF with a frequency of 8 Hz influences more expressively the pigeons conditioned activity in comparison with 5 Hz frequency.
Animals↗
[Elaboration of an alimentary conditioned reflex to electric stimulation of septal nuclei in dogs].
An alimentary instrumental conditioned reflex was elaborated in four dogs to electrical stimulation of the septum medial and lateral areas. Elaboration proceeded differently depending on localization of the stimulating electrode: in response to electrical stimulation of the medial septal area it was achieved more rapidly than to stimulation of the lateral area. Typical inhibitory effects of food-procuring reactions to stimulation of the lateral area were recorded, which disappeared in the process of conditioning. The elaborated stable conditioned reflex could be extinguished and restored.
Animals↗
[Formation of two systems of conditioned reflexes with random alteration of stimuli].
Two heteromodal systems of secretory positive and inhibitory reflexes were elaborated in non-learned dogs to conditioned stimuli presented according to a four-digit table of random figures; then a third system was elaborated. All the systems were presented with one-day intervals in strict alteration (in a stereotype). It has been shown that the formation of a stereotype out of systems of secretory conditioned reflexes, organized at random, is characterized by an enhanced general functional state (tone) of the brain. A comparison of the results of the present work with previous investigations of simultaneous formation of two heteromodal rhythmical stereotypes leads to the conclusion that the structure of the systems in which the conditioned reflexes are formed is the major factor, not the structure of the reflexes.
Animals↗
Postnatal development of conditioned reflex behavior: comparison of the times of maturation of plastic processes in the rat hippocampus.
The formation of conditioned reflex fear, escape responses, and conditioned avoidance responses during acquisition of a conditioned two-way avoidance reflex was studied in rats of different ages. Rats aged 16-17 days acquired the conditioned reflex but not the escape reaction or the conditioned avoidance response; acquisition efficiency was higher than in adult rats. Escape responses appeared from postnatal day 18. The ability to acquire this type of learning was complete by age 3-4 weeks. Maturation of the mechanisms of the "classical" (the fear phase) and operant (transfer to another sector in response to the unconditioned stimulus) components did not facilitate acquisition of the conditioned two-way avoidance reflex until the middle of postnatal week 4. Learning efficiency in four-week-old rats was lower than in adults. It is suggested that the maturation of different types of memory may be associated with the periods at which plastic processes develop in the hippocampus.
Aging↗
[Activity of hypothalamic neurons during elaboration of a defensive conditioned reflex].
During elaboration of conditioned defensive reflex to combinations of acoustic and electro-cutaneous stimuli in alert rabbits 44% out of 86 neurones in the ventromedial nucleus and 42% out of 40 cells in the perifornical nucleus of the hypothalamus elaborated conditioned responses. 71% of ventromedial neurones and 53% of perifornical cells (out of those that were conditioned) showed inhibitory responses while the rest demonstrated an activation. In half of the neurones that showed conditioned responses it was possible to elaborate differentiation and extinctive inhibition. Significant conditioned responses appeared following 20-30 pairings of sound and electro-cutaneous stimulation. Their extinction took place after 10-20 non-reinforcements. A correlation was found between conditioned activity of neurones in the ventromedial nucleus groups and changes in heart-rate. Different roles of lateral and medial nuclear groups of the hypothalamus in conditioning were shown. This may point to their participation, along with other brain structures, in the formation of respectively vegetative and motor components of the integrative behaviour.
Animals↗
[Instrumental conditioned reflexes to salt and acid stimuli in carp].
In experiments on unrestrained carps, a comparative study was made of the analysis of different concentrations of NaCl and HCl (starting with threshold ones) by means of instrumental conditioned reflexes, aimed at eliminating harmful chemical stuffs from water medium. Salt concentrations, in response to which the formation of a conditioned reflex is possible (3--9 mM) are by an order higher than those for the acid (0.3--0.85 mM). The intensity and duration of manifestation of the defensive conditioned reflex depend directly on the strength (concentration) of the chemical stimulus. Cessation of motor conditioned reaction providing for restoration of the optimal conditions of the surrounding takes place when initial concentration of the stimuli in experimental reservoir is reduced to values close to threshold ones, namely to about 2 mM for NaCl and to about 0.2 mM for HCl, i.e. to a minimal concentration compatible with normal vital activity. After extirpation of the forebrain, the fish lose the capacity for active elimination from the surroundings of both salt and acid components.
Animals↗
[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.
Amygdala↗
[The role of the temporal areas in conditioned reflex activity following section of the brachia of the inferior colliculi].
The role of the neocortex temporal areas in the closing function was studied in chronic experiments on cats in the norm and after section of the posterior colliculi brachia. The techniques of functional elimination of the temporal neocortex by cold and section of the posterior colliculi brachia were used. Functional elimination of the cortical temporal areas prevents formation of a stable conditioned reflex in the first twenty sessions with cooling. Conditioned reflexes elaborated after section of the posterior colliculi brachia are not manifested in the case of cooling of the temporal areas throughout the period of observation (18 sessions). At the same time the conditioned reflexes elaborated before the section, are restored quite rapidly (five to six sessions). Hence, the neocortex temporal areas are more important for setting up conditioned connections than for their preservation and the use of connections previously elaborated.
Animals↗
[Influence of psychotropic substances on elaboration of a defensive conditioned reflex in experimental neurosis].
Neurosis resulting in alteration of the motor-defense conditioned reflex development occurred in rats subjected to a long-term action of a negative-emotional factor--neighbour-rat's reaction to pain. Benactyzine, diazepam, chlordiazepoxide, and sodium hydroxybutyrate improved the formation of defense conditioned reflex during this form of neurosis. Trioxazin, trifluoperazine, and amphetamine produced no such effect. The proposed model of experimental neurosis can be used to reveal the tranquilizing activity of psychotropic drugs.
Animals↗
On the functional stucture of conditioned reflexes to serial stimuli in dogs.
The functional structure of conditioned reflexes to a stimulus series has been studied. The serial stimulus consisted of a tone of 600 Hz, passive lifting of the right forepaw, and a puff of air directed at the eye, the latter component of the series being reinforced by food. Four dogs were wed. Objective registration of the effector manifestations to each component stimulus has shown that, during the elaboration of a conditioned alimentary reflex to the serial stimulus, conditioned connections are formed by each component with the alimentary center and by each preceding stimulus with all subsequent stimuli, irrespective of their position in the series. All excitation foci which function in the given stimulus set become interconnected. Direct connections of each stimulus component with the alimentary center are never inhibited. The multiplicity of duplicating direct connections and the presence of backward connections impart to composite reflexes the reliability and adaptive strength which is necessary for the formation of behavioral acts.
Animals↗