Formation Of Reflex Research Articles

Participation of midbrain periaqueductal gray matter in defense conditioning in rats

Responses of neurons of the periaqueductal gray matter (PAG) were studied in chronic experiments on cats during formation and extinction of a defensive conditioned reflex to sound and its differential inhibition. In response to conditioned stimulation these neurons developed phasic-tonic spike responses up to 3 sec in duration. During combination of stimuli these responses were formed long before the conditioned reflex and disappeared long after the latter was extinguished. In the case of an established conditioned reflex, the onset of spike responses occurred 100–200 msec before the appearance of motor responses. An increase in spike activity of tonic character in neurons of PAG preceded voluntary movements by 100–500 msec. The responses of these neurons to presentation of a differential stimulus consisted of groups of spikes 150–200 msec in duration. They were formed with difficulty, and their manifestation was made even more difficult by an interruption during the experiment and by preceding positive stimuli. On the basis of the results a conditioned reflex can be regarded as the result of a multilevel hierarchic process of readjustment of unit activity, which begins in the nonspecific structures of the midbrain.

Responses of limbic cortical neurons during instrumental conditioned reflexes in cats

Unit activity in cortical areas 24 and 32 was studied during conditioned placing reflex formation in cats. Neuronal responses in the limbic cortex of trained animals correlated with acoustic stimulation, the motor response, and also with the presentation of food reinforcement. In untrained animals 16% of neurons responded to acoustic stimulation. After training the number of neurons responding to sound in area 32 increased to 51.3%. Of the total number of neurons, 34.6% responded by initial excitation and 26.7% by inhibition of spike activity. The latent period of these responses was about 50 msec and their duration up to 200 msec. Similar but weaker responses were observed in area 24. Short-latency activation responses to conditioned and differential stimulation were similar in character. It is suggested that after training processes taking place in the limbic cortex may contribute to better perception of both conditioned and differential acoustic stimuli, irrespective of their functional significance.

Effect of the antioxidant ionol on formation and persistence of a defensive conditioned reflex during peak exercise

Effect of the antioxidant ionol on formation and persistence of a defensive conditioned reflex during peak exercise

A model reproducing the characteristics of conditioned reflex formation and manifestation.

A model reproducing the characteristics of conditioned reflex formation and manifestation.

Defensive conditioning in Helix lucorum and associated changes in command neuron activity.

1. During a combination of food stimulation with electrical stimulation inHelix lucorum for 5–15 combinations a defensive reflex showing all the properties of a conditioned reflex is formed. 2. Between 40 and 60 min after formation of the conditioned reflex a spike response appears in command neurons of defensive behavior in response to the conditioned stimulus, and lasts throughout the experiment. The response to the food stimulus in command neurons of food behavior is very slightly reduced. 3. The changes taking place are the result of plastic changes in sensory cells of the defensive reflex arc.

Participation of the auditory cortex and emotiogenic subcortical systems in conditioned reflex formation and realization.

1. Different combinations of appearance of a conditioned EP in brain structures lead to the realization of a conditioned neurographic response with different degrees of probability. 2. The determining factor in the appearance of a conditioned neurographic response is an increase in probability of appearance of a conditioned EP in the auditory cortex, zona incerta, and preoptic region. The simultaneous appearance of a conditioned EP in these structures facilitates stable realization of the conditioned neurographic response, a fact which indicates the special significance of these structures in the mechanisms of formation of the conditioned effector response.

Hemisphere lateralization of inductive and deductive processes.

Experiments were performed on 453 Wistar rats. Motion-food and electrodefensive behavioral techniques were applied. The following models were used: a conditioned reflex formation, generalization and specialization of a conditioned reflex, the dynamic stereotype, visual image synthesizing, a conditioned reflex to a stimulus complex. Primary and secondary analysis and synthesis of stimuli were discriminated. Induction and deduction were considered as a certain sequence of analysis and synthesis in time. Primary analysis and secondary synthesis were shown to be mainly lateralized in the left hemisphere and primary synthesis and secondary analysis in the right one. The conclusion was drawn that, in animals, the left hemisphere processes information mainly according to the principle of induction (from the particular to the general) and the right one does so according to the principle of deduction (from the general to the particular).

Relationship between noradrenalin uptake and secretion by cortical nerve endings in rats during conditioning

The intensity of highly selective uptake (inactivation) of noradrenalin (NA) and of spontaneous and evoked secretion by synaptosomes in the rat cerebral cortex were investigated by the use of [3H]-NA 30 min after defensive conditioning. Changes in the efficiency of adrenergic synaptic transmission during formation and fixation of the temporary connection were judged on the basis of these parameters. Changes in uptake and spontaneous secretion were not observed in the trained and control rats, whereas the intensity of its secretion induced by KC1 (60 mM) was considerably higher in the trained rats than in the controls. An increase in the intensity of evoked secretion was observed only during conditioned reflex formation. It is concluded that conditioning leads to a specific increase in the efficiency of adrenergic synaptic transmission, which is observable in nerve ending isolated 30 min after formation of the reflex.

Effect of thymectomy and thymus polypeptide factor on instrumental reflex formation to food in rats

Effect of thymectomy and thymus polypeptide factor on instrumental reflex formation to food in rats

Effect of single physical exertion on formation, fixation, and reproduction of temporary connections in rats

One way of studying the nature of consolidation of temporary connections in the CNS is to investigate and compare the influence of various procedures modifying the functional state of the body as a whole, and of the higher levels of the CNS in particular, on this process. Among the many different factors influencing this process, physical exertion has been studied less than others although, according to some data, physical exertion can have a marked influence on higher nervous activity [I, 3, 6]. The object of this investigation was to study the effect of single submaximal and maximal physical exertion on the formation and consolidation of temporary connections. EXPERIMENTAL METHOD Experiments were carried out on noninbred male albino rats weighing 150-180 g, in which conditioned passive and active two-way avoidance reflexes (CPAR and CAAR respectively) had been formed. The CPAR was formed in an apparatus consisting of a lit "safe" and a dark "dangerous" compartment, connected by a window. To form the CPAR a rat was placed in the lit compartment, from which a change into the dark compartment was accompanied by an electric shock (ES). The ES continued until the animal returned into the "safe" compartment, after which the rat was removed from the apparatus and returned to the animal house~ Preservation of CPAR was tested 1 h and 1 and 7 days after its formation by placing the animal in the lit compartment and recording the time of its stay therein. The maximal time of observation per animal was 300 sec. The CAAR was formed in a shuttle box, using light as the conditioned stimulus, reinforced at the 6th second of action of ES. In the initial and repeated experiments (the last was done 7 days after the initial) the animal was presented with 50 combinations of light and ES and the number of conditioned avoidance reactions was recorded. The number of conditioned avoidance reactions served as the indicator of reflex formation in the initial experiment and of its preservation in the repeated experiment. Two series of experiments were carried out, each of them on two groups of animals. In series I the effect of submaximal and maximal physical exertion on formation and preservation of the CAAR and CPAR was investigated. The submaximal load consisted of running in a circular treadmill rotating at a speed of 16 m/min for I0 min, whereas maximal exertion consisted of running in the treadmill up to the limit of endurance. The mean duration of running in this case was 66 min. In the experiments of series II the animals were subjected to submaximal and maximal physical exertion immediately after formation of the CPAR or CAAR. By comparing the results of these two series it was possible to assess the influence of physical exertion on the formation, fixation, and subsequent preservation of temporary connections, The Wilcoxon--Mann--Whitney method was used for statistical analysis~ Altogether more than 200 animals were used in the experiments. EXPERIMENTAL RESULTS

Time course of formation of instrumental conditioned reflexes to water and food in unrestrained dogs.

1. The behavior of unrestrained dogs with freedom of choice of reinforcement at each given moment is determined by the relationship of excitability of the structures of the corresponding vitally important unconditioned reflexes. 2. By modifying in a definite way the excitability of structures of unconditioned reflexes (food and drinking), under conditions of choice of reinforcement an animal's behavior can be made strictly single-purpose (feeding or drinking). 3. The physiological mechanism controlling animal behavior is a mechanism of formation of two-way (forward and backward) conditioned connections. The concrete form of goal-directed behavior is determined by activation of the corresponding backward conditioned connection.

Unit activity during the formation of backward conditioned connections.

1. During the formation and stabilization of a conditioned food reflex to electrical stimulation of structures of the visual system (LGB and OT) a pattern of unit activity that differs significantly from that during pseudoconditioning becomes organized. 2. Most neurons investigated had a different time course of their discharge activity during periods of isolated and combined action of the conditioned and reinforcing stimuli. 3. Neuronal parameters of backward conditioned connections during activation of the structures of the reinforcing stimulus are analogous to responses of neurons in this region of the cortex to the action of the conditioned stimulus. 4. Backward conditioned connections can be demonstrated by neuronal parameters on visual cortical cells specialized with respect to their afferent properties.

Late components of evoked potentials in cortical projections of paired stimuli during food conditioning to electrical stimulation of the lateral geniculate body.

1. The possibility of formation of a conditioned food reflex to stimulation of the lateral geniculate body (LGB) was demonstrated and its features are described. 2. Formation of a conditioned reflex to stimulation of LGB is accompanied by the appearance of intensification of the late positive-negative component of EP in the visual and sensomotor cortex, with similar configuration. The peak latency of the negative component in the cortical areas studied was 40–80 msec. 3. The amplitude of the late positive-negative complex of the EP in the cortical areas studied differs during periods of isolated and paired action of the conditioned and reinforcing stimuli.

Effect of intermittent hypokinesia of varied duration on conditioned reflexes, the EEG, and blood neurotransmitter levels in rats.

1. Intermittent hypokinetic states (from 1 to 6 weeks in duration) bring about a combination of behavioral, autonomic, conditioned-reflex, bioelectrical, and neurotransmitter disturbances which depend on the duration of immobilization. 2. Immobilization of animals for 1 week leads to the development of an acute state of emotional stress expressed as abnormal motor excitation, a disturbance of defensive conditioning, an unstable pattern of sleep and waking, and liberation of catecholamines into the blood stream with a predominantly relative increase in the adrenalin concentration. 3. Immobilization for 3 weeks is accompanied by the development of a compensatory systemic reaction with improvement of conditioned-reflex activity, stabilization of the sleep-waking sycle, and a sharp increase in the relative blood noradrenalin level accompanied by a further rise in blood catecholamine levels. 4. Immobilization for 6 weeks causes the appearance of the initial signs of exhaustion of the adaptive systems of the body: intensification of protective grooming reactions, worsening of defensive conditioned reflex formation, changes in the quantitative and qualitative characteristics of sleep, and a fall in the blood catecholamine and acetylcholine levels.

Problems in the Integrated Study of Individual Differences

The properties of all the stages of evolution of matter, from the chemical to the sociohistorical, are part of man as well. In each of these properties, in addition to what is common and typical for groups of people, there is something that is unique to the individual and irreproducible. One characteristic noted in theoretical conceptions of individual differences is that they tend to study properties relating to different stages in the development of matter in isolation from one another. In most studies of differential psychophysiology, the biochemical and endocrine properties of the organism and the bioelectric properties of the nervous system are examined as if they had nothing to do with individual characteristics in the formation of classical Pavlovian conditioned reflexes. The psychological properties of the personality are examined in the Vygotsky and Leont'ev school independently of their relationship to somatic, neurophysiological, and psychodynamic properties (the properties of temperament).

Effect of anodal polarization of deep brain structures on spatial synchronization of cortical potentials during defensive conditioning in rabbits.

1. Reversible blocking of some nonspecific thalamic and hypothalamic nuclei differs in its effect on two types of spatial synchronization of cortical potentials (SSCP) formed during defensive conditioned reflex (DCR) formation: Specific local SSCP and conditionedreflex movements disappear, whereas global SSCP remains virtually unchanged under these circumstances in interstimulus periods. 2. By modifying their functional state of these nuclei by anodal polarization it is possible to influence the rate of DCR formation. The effect of polarization depends on the structure to be stimulated and the stage of reflex formation. 3. During temporary blocking of hypothalamic nuclei phasic changes arise in local SSCP, which was never observed after blocking the nonspecific thalamic nuclei. 4. During reversible blockade of subcortical structures synchronization of cortical and subcortical potentials is depressed first. Conditioned-reflex movements appear only when synchronization between cortex and subcortex is recovered. 5. The conclusion can be drawn from the results that the mammillary bodies play an important role in the formation of local SSCP at the beginning of DCR formation and that the nonspecific thalamic nuclei and the posterior hypothalamic nucleus are essential for this form of spatial synchronization to arise on stabilization of the reflex, when definite correlation is observed between the appearance of local, specific SSCP, realization of the reflex, and strengthening of synchronization between the cortex and subcortical formations.

Changes in steady potential level and in brain bioelectrochemical potential during orienting and conditioned reflexes in rabbits.

1. The orienting reaction in rabbits is accompanied by generalized shifts of SPL in the cortex in the absence of changes in BECP. 2. Changes in BECP appear only during conditioned reflex formation and develop during combination of the conditioned and reinforcing stimuli. During combination shifts of SLP also are observed, and in their configuration and amplitude they differ from those occurring during OR. 3. Simultaneous recording of changes in BECP and shifts of SLP developing during combination of conditioned and reinforcing stimuli shows that the two phenomena are the external manifestation of independent processes. 4. It is postulated that brain activity concerned with the perception and analysis of the informational significance of a stimulus is linked more closely with bioelectrical than with metabolic processes. During a combination of two stimuli in the process of conditioned reflex formation, besides the strengthening of activity linked with bioelectrical processes, a new type of activity accompanied by considerable metabolic shifts appears. 5. Recording changes in the electrochemical potential of an electrode made of inert metal is a highly rewarding method for studying the spatiotemporal organization of metabolic activity of the brain, connected with higher nervous activity.

Functional details of the basal ganglia as related to the spatial organization of their fibers in cortex and thalamus

This study compared the results of experimental-morphological and physiological studies in which facts were obtained regarding the functional and morphological heterogeneity of the basal ganglia. Experiments were done on dogs in order to study delayed responses and Hunterian delayed choice responses. Electrical and chemical stimulation of striopallidal structures and recording of spike activity in neurons were done in cats during the formation of conditioned reflexes. Morphological studies were done on cats and dogs by the technique of axon-terminal degeneration. On the basis of an analysis of our own data and data in the literature we have advanced the hypothesis that: 1)There is a correlation between the general features of the disturbance in higher nervous activity and the overlap of striopallidal projections onto cortical and thalamic structures; 2) in a series of cases the behavioral disturbance after shut-off or stimulation of the thalamic structures; 2) in a series of cases the behavioral disturbance after shut-off or stimulation of the basal ganglia can be correlated with the topical details of their projection onto cortical fields and thalamic nuclei.

Conditioned reflex to time in Helix lucorum.

1. By the use of the classical motor-defensive method of conditioning to “pure time” in experiments onHelix lucorum changes can be detected in the responses of the pneumostome taking place during formation of the reflex. 2. The newly formed reflex is conditioned with respect to its basic properties. 3. The similarity of the properties of the conditioned pneumostome reflex formed inHelix lucorum and the conditioned reflex to “pure time” in higher animals suggests a similarity of the neurophysiological mechanisms of formation of the reflex. 4. The results indicate the important role played by constantly acting factors of the experimental situation in the process of formation of a conditioned reflex to “pure time” in the snail.

Formation of a motor food-getting conditioned reflex with two-way connection in Helix lucorum.

1. During a combination of tactile stimulation of the body surface ofHelix lucorum with food reinforcement a conditoned food-getting reflex is formed. 2. This reflex possesses all the properties of a true conditioned reflex: stability, ability to recover spontaneously after extinction, and specificity of response to a chosen conditioned stimulus. 3. The conditioned food-getting reflex inHelix lucorum is similar in its basic characteristics to conditioned reflexes in higher vertebrates in their simplest form. 4. A combination of two unconditioned stimuli leads to the formation of a two-way reflex. 5. The reversed conditioned connection is weaker than the direct and is characterized by variability, instability, and diversity in its manifestations.