Extinction of the defensive conditioned reflex in cats after lesioning the endopeduncularis nucleus]

Influence of bilateral destruction of nucleus entopeduncularis on the extinction of conditioned avoidance was studied in 10 adult cats. It was shown that bilateral destruction of the nucleus entopeduncularis led to a disturbance of storage of the previous conditioning and facilitated repeated extinction.     

The neurochemical basis of recurrent inhibition in the reflex arch of the defensive reaction]

Mechanisms of habituation in the network of identified neurones were investigated in isolated preparation of central nervous system in the snail Helix. It has been found that intracellularly induced spike discharge in premotor command neurones decreases synaptic responses to repeated nerve stimulation in all recorded command neurones. Application of the neuropeptide FMRFamide elicits similar changes in the network. Taking into account that the investigated command neurones contain FMRFamide, as was shown immunochemically, it is possible to assume the existence of recurrent inhibition in the network underlying avoidance reactions. This recurrent inhibition causes habituation of the network output in the cases when the repeated stimuli do not evoke sensitization via activation of serotonergic cells.     

The status of conditioned reflex activity in cats after unilateral vestibular neurotomy]

In chronic experiments on 6 cats the influence was studied of unilateral vestibular neurotomy on conditioned, oculographic and electrocardiographic reactions. In operated animals appeared sharply expressed posetonic and oculomotor disturbances, lowered general functional brain state, what was manifested in an increase of specific weight of slow spindle-shaped rhythmics and lowering of the conditioned activity level. Against the background of the lowered functional brain state interhemispheric asymmetry developed with relative predominance of the contralateral hemisphere, what was reflected in electrocorticographic manifestations and disturbance of conditioned spatial differentiations. Significance is grounded of the appearing interhemispheric asymmetry in the development of disturbances of spatial analysis in operated animals.     

Complex alimentary motor conditioned reflex reactions in cats and dogs]

The ability of animals to perform a complex motor task representing a model of compensatory discrete tracing was investigated in dogs and cats. Elongation of a light spot on an oscilloscope screen into a vertical line served as a signal of motor reaction. The reaction consisted in several movements, each of which reduced the initial signal change by 1/2, 1/3, 1/4 or 1/5 of its value. Alimentary reinforcement was given only after a reduction of the signal to its initial level. Signals with a different number of steps of transition to their initial state were presented at random. It was found that learned animals were capable of a stable behaviour of a compensatory discrete tracing type. A hypothesis has been advanced about a probabilistic participation of visual control in the realization of tracing motor behaviour.     

Neurons of the rabbit midbrain reticular formation during a defensive conditioned reflex]

Analysis of unit activity of the midbrain reticular formation was carried out on alert rabbits during defensive conditioning. Most of the examined neurones exhibited phasic responses corresponding in time to the components of the evoked potential (EP) recorded in the cortical visual area in response to the "indifferent" stimulus, and to the conditioned stimulus and electric cutaneous reinforcement. The data obtained are considered from the standpoint of the Anokhin functional systems theory. A conclusion has been made regarding the participation of reticular units in providing all the basic mechanisms of the functional system of the behavioral act. Discharges of one and the same neurone may correspond to different components of the EPs to conditioned and unconditioned stimuli. In different behavioral acts a neurone may apparently participate in different systemic mechanisms.     

Heart rate deceleration is not an orienting reflex; heart rate acceleration is not a defensive reflex

Graham and Clifton (1966) proposed an integration of Sokolov's theory of orienting and defensive reflexes with the stimulus intake/rejection dichotomy of the Laceys. This integration consisted of hypothesizing that heart rate deceleration is a measure of the orienting reflex, and that cardiac acceleration is a measure of the defensive reflex. This article demonstrates that Graham and Clifton failed to establish a valid integration of these two theories. This failure is a consequence of 1) their misconstruing Sokolov's theory, and 2) an inaccurate and selective review of the research literature then available. Consideration of more recent research would seem to rule out the possibility that their thesis was correct in spite of these flaws in its derivation. Cardiac responding in the OR context thus remains open to further investigation and interpretation.     

The effect of phenamine and caffeine on caudate inhibition of conditioned reflex avoidance reactions in cats]

In cats with a preliminarily learned conditioned avoidance reaction, stimulation of the caudate nucleus inhibited behavioral response by lengthening its latency and reducing the number of conditioned reactions. Intensity of the inhibitory effect did not substantially depend on the localization of electrodes in the head or body of the nucleus and weakened within a few experimental days. D,1-amphetamine (0.5 to 4 mg/kg) and caffeine (10 to 10 mg/kg) suppressed the caudate inhibition, but the action of the drugs was manifested in different ways. The influence of large doses of d,1-amphetamine was characterized by a serious disturbance of behaviour and caudate inhibition of conditioned responses.     

The active electrogenesis of the command neurons in the defensive behavior of the mollusk during conditioning]

In the paper changes of active electrogenesis of the command neurones of defensive closure of snail pneumostome at elaboration, extinction and repeated elaboration of classic conditioned defensive reflex to tactile stimulus was described; the tactile stimulation of other point of the body served as a differentiating stimulus. During the increase of biological significance of conditioned stimulus as a result of learning the stimulation of the command neurones in response to this stimulus was raised. At the same time the neurones showed decreased excitability in response to differentiating stimulus. Possible mechanisms of quick reconstruction of neurones excitability and functional value of PA generation threshold changes were discussed.     

The effects of neuroleptics and nialamide on defensive conditoned reflex in rats.

Experiments were carried out on male Wistar rats after development of defensive conditioned relex during 6 weeks of training. In one series of experiments chlorpromazine, haloperidol, pimozide or fluspirilene were used in doses of 0.05, 0.5 and 5.0 mg/kg intraperitoneally. In another series of experiments nialamide was given intraperitoneally in a dose of 140 mg/kg 16--18 hours before administration of one of these neuroleptics. A delay in the time of appearance of the defensive conditioned refex was observed after administration of neuroleptics in all animals. In some rats neuroleptics caused complete disappearance of the conditioned refex as well as the defensive unconditioned refex. Previous inhibition of monoamine oxidase activity obtained with nialamide increased evidently the inhibitory effect of the studied neuroleptics on the appearance of defensive conditioned reflex.     

Time-dependent responses of expiration reflex in cats

We investigated the effectiveness of the "expiration reflex" in 10 anesthetized spontaneously breathing cats. The expiration reflex was produced by mechanical stimulation of the vocal folds and electrical stimulation of the superior laryngeal nerve at different moments in the respiratory cycle and at various levels of respiratory chemical drive. The effectiveness of the expiration reflex was evaluated from sudden changes in expiratory flow immediately following the stimulation. Both mechanical and electrical stimulations given during early inspiration caused little or no expiratory efforts, whereas stimulations given during early expiration or hypocapnic apnea produced a typical expiration reflex. Changes in arterial CO2 and O2 partial pressures influenced neither the relationships between the stimulation and its effect on the expiration reflex nor the strength of the expiration reflex. These results indicate that the timing of stimulation with relation to the phase of the respiratory cycle is critical to its effect on the expiration reflex and that changes in respiratory chemical drive do not modify the expiration reflex characteristics.     

The mono- and polysynaptic connections between identified neurons in the system of the passive defensive reflex in the edible snail]

A structure of synaptic connections between the identified sensory and giant command neurons of Helix lucorum was studied. It was found that EPSPs arising in the giant neuron as responses to single action potentials generation in sensory neuron consist of several monosynaptic and several polysynaptic components having different magnitude, latencies, and plasticity. The latencies of monosynaptic components are determined by different presynaptic terminals' lengths.