Formation Of Conditioned Reflex Research Articles

INDIVIDUAL AND AGE PROPERTIES OF BEGINNING SINGERS AND THEIR INFLUENCE ON THE PROCESS OF VOCAL SKILLS’ FORMATION

The article examines the influence of individual and personal properties of junior and teenage pupils, which significantly affect the ontogenesis of musical abilities and their singing training. It was noted that taking these factors into account should lay the foundation for teaching singing to pupils of different ages. In teaching singing to elementary school students, attention is focused on the fact that, due to the adverse influence of the musical environment, a significant proportion of children develop a so-called «partial brake», which becomes an obstacle to the spontaneous and natural mastery of the skills of repeating the simplest melodies, and with it, to the development of pitch hearing, harmonic sense, musical memory and internal auditory images. The internal and external factors of these inhibitory processes are characterized, which include the peculiarities of children’s temperament and behavioral tendencies and their combination with habits that are formed in them as a result of pedagogical mistakes and family circumstances that negatively affect the process of realizing their speech and intonation potentials. Two types of temperament and the peculiarities of their manifestation in the process of teaching singing students are distinguished, namely: choleric temperament with a preference for the excitatory state of the nervous system and melancholic temperament with a characteristically weak type of nervous system and a preference for inhibitory processes. These properties often lead to the emergence of problems in the individual at the initial stage of musical development and negatively affect their condition throughout life. The external signs of their manifestation are the condition of the muscular body, the peculiarities of speech and communication, tending to the corresponding behavioral style. In the first case, the student’s excessive activity, general muscle stiffness, the need to quickly switch attention and the inability to concentrate it on the performance of tasks, the inability to act on the advice (instructions) of an adult are characteristic. For children with impaired tone of the nervous system, an overly relaxed, «flabby» muscle state is typical, which negatively affects the lack of support in the process of sound production and sound conduction, increased fatigue, slow formation of conditioned reflexes, which are the basis of the motor-singing skills formation. Keywords: individual and age psychological properties; development of musical abilities; singing lessons; vocal skills; students of different ages.

Secrets of memory. Biological and computer parallels

This article explores one of the most mysterious and multifaceted aspects of human nature - memory. Memory defines the system's ability to learn, adapt, and make informed decisions based on accumulated experience. It plays an important role in solving conceptual and theoretical problems in the field of artificial intelligence and modeling. Learning and adaptation is one of the key aspects where memory models allow AI systems to not only reproduce but also improve their performance based on experience. It is also important to consider memory modeling as preserving the context of past events, which is important for the correct understanding and interpretation of current situations. The article examines the issue of memory location, starting with classical theories explaining the mechanisms of memory location in the brain, including neurophysiology and the theory of conditioned reflexes. However, special attention is paid to alternative approaches, such as the theory of intracellular memory, which offers new ways of understanding memory. Finally, the work draws attention to the connection between learning and memory, especially in the context of the formation of conditioned reflexes. In the process of considering the neuron as a key element of the nervous system and studying protein synthesis and polyribosomes, a surprising similarity between the process of protein synthesis in neurons and the functioning of the Turing machine was revealed. In the context of this analogy, a neuron can be perceived as a molecular computer, providing a new level of understanding of memory formation and information processing in the brain. The author hopes that this research will help to better understand the nature of human memory and enrich our knowledge about how the brain works

METHODOLOGY OF FORMATION OF CONDITIONED REFLEX "AGENDA" IN PRIMARY SCHOOL PUPILS

METHODOLOGY OF FORMATION OF CONDITIONED REFLEX "AGENDA" IN PRIMARY SCHOOL PUPILS

Neural-like growing networks in the development of general intelligence. Neural-like growing networks (P. II)

This article is devoted to the development of general artificial intelligence (AGI) based on a new type of neural networks – “neural-like growing networks”. It consists of two parts. The first one was published in N4, 2022, and describes an artificial neural-like element (artificial neuron) in terms of its functionality, which is as close as possible to a biological neuron. An artificial neural-like element is the main element in building neural-like growing networks. The second part deals with the structures and functions of artificial and natural neural networks. The paper proposes a new approach for creating neural-like growing networks as a means of developing AGI that is as close as possible to the natural intelligence of a person. The intelligence of man and living organisms is formed by their nervous system. According to I.P. Pavlov's definition, the main mechanism of higher nervous activity is the reflex activity of the nervous system. In the nerve cell, the main storage of unconditioned reflexes is the deoxyribonucleic acid (DNA) molecule. The article describes ribosomal protein synthesis that contributes to the implementation of unconditioned reflexes and the formation of conditioned reflexes as the basis for learning biological objects. The first part of the work shows that the structure and functions of ribosomes almost completely coincide with the structure and functions of the Turing machine. Turing invented this machine to prove the fundamental (theoretical) possibility of constructing arbitrarily complex algorithms from extremely simple operations, and the operations themselves are performed automatically. Here arises a stunning analogy, nature created DNA and the ribosome to build complex algorithms for creating biological objects and their communication with each other and with the external environment, and the ribosomal protein synthesis is carried out by many ribosomes at the same time. It was concluded that the nerve cells of the brain are analog multi-machine complexes – ultra-fast molecular supercomputers with an unusually simple analog programming device.

The Role of The Hippocampus in Conditionally Reflective Activity and The Formation of The Functional State of The Crust of The Large Hemisphere

The studies were carried out on dogs, which were stereotactically implanted with depth electrodes in the ventral and dorsal parts of the hippocampus. We studied the effect of stimulation of these structures with an electric current of high (60 pulses/sec) and low (4 pulses/sec) frequencies on conditional reflex activity and the formation of the functional state of the cerebral cortex. It was revealed that stimulation of different structures of the hippocampus has a different effect on the tone of cortex cells. The nature of this influence depends on the frequency of the electric current, which was used to stimulate. Formulation of the problem. Analysis of recent research and publications. There are a number of scientific papers devoted to the study of the role of the hippocampus in the regulation of various body functions (Giuliana, Caronia, Jennifer, Wilcoxon, et all., 2010; Purvis, EM, O'Donnelly, JC et all, 2020). Some authors believe that the hippocampus is a poly-functional structure: the center of visceral functions and sense of smell, memory, and learning, the regulator of emotions and motivations, it is used for orientation reflexes and attention, sensory analysis (Chaychenko, G.M., 1984; Wiskott L, Rasch MJ, Kempermann G. Wiskott L, Rasch MJ, Kempermann G. et all. 2006). But today there is not enough reliable data on the role of this structure in conditioned reflex activity under conditions of electrical stimulation of various structures of the hippocampus. It was found that when the hippocampus is stimulated by a weak electric current during the formation of conditioned reflexes, the fixation time of the reflex is significantly reduced, ie the processes of memorization and learning are accelerated (Gray, J.A., 1983; Diana, X Yu, Maria, C Marchetto, Fred, H Gage, 2014; Nader, K, Krysiak A, Beroun, A, et all., 2019; Whitfield, JF, Chakravarthy, BR., 2009). The mechanism of temporal connections has been shown to play an important role in regulating cortical tone. If the question of the formation of the functional state of the cortex of the large hemispheres during the formation of conditioned reflexes is more or less studied, then the question of the dependence of this phenomenon on the properties of the inhibitory process is insufficiently studied (William, D Jones, Sarah, M Guadiana, Elizabeth, A Grove, 2019). In addition, the role of various subcortical structures and, in particular, the hippocampus in the regulation of the tone of the cortex of the large hemispheres has not been clarified to date. The purpose to establish features of the formation of a functional condition of the bark of large hemispheres in the conditions of electric stimulation of various structures of a hippocampus

Neuromorphic model of associative memory in the formation of the working environment description of a robotic agent

The article considers an approach to solving the problem of describing the workspace of a robotic agent based on the neuromorphic principle. A segmental spike model of a neuron with the possibility of structural adaptation was used as a basic element in the modeling. The main features of the neuron model used in terms of the possibilities of its structural reconfiguration are indicated. As the basis of the model for such a description, a scheme for the formation of a conditioned reflex in living organisms is chosen. The structural scheme of the neuromorphic model of conditioned reflex formation is given, as well as the general scheme of the model of associative memory formation. A step-by-step description of the algorithm for forming associative links in such a scheme is given. The principle of the formation of inhibitory connections when competing features appear in several objects is presented. The article presents the results of computer modeling on a model example. The conclusion is made about the applicability of the chosen neuron model and the scheme of organizing neurons into a network to solve the problem of describing the workspace of a robotic agent.

DEVELOPMENT OF A TECHNIQUE FOR MODELING A DEPRESSIVE STATE IN RAT BY STEREOTAXIС INJECTION OF LIPOPOLYSACCHARIDE INTO THE HIPPOCAMPUS

Introduction: Currently, various mechanisms of the development of depression are known. At the beginning of the 21st century, a new era began in the study of the pathogenesis of this disease. It has been shown that the development of a depressive state is closely associated with neuroinflammation. As a result, it became necessary to develop methods for modeling depression, which will cause inflammation in a strictly defined area of the brain. Purpose of the work: Creation of a model of the depressive state in rats by stereotaxic injection of LPS into the hippocampus. Materials and Methods: Ten female Wistar rats were randomly divided into a control group (n = 3), an LPS-treated group (n = 4), and a sham-operated group (n = 3). LPS was administered at a dose of 30 μg / animal in a volume of 3 μL over 30 min, according to the following stereotaxic coordinates: AP: -3, ML: 2, DV: 3. Depression was assessed in psychopharmacological tests: hole-board test, open field, elevated plus maze, dark-light chamber, Porsolt forced swimming test, sucrose test. The formation of conditioned reflexes of passive avoidance was studied. To assess the localization of the injection, an MRI scan was performed on the 7th day. The result of LPS injection was analyzed on histological preparations. Results: During testing of animals in the setting of a dark-light chamber and an elevated plus maze, it was found that the control and sham-operated groups did not have statistically significant differences. At the same time, the time spent by the rats in the light compartments increased in the experimental group. In the Porsolt forced swimming test, there are statistically significant differences in the time of immobilization of animals. Also, in the rats of the experimental group, the latent period of the onset of reversible actions increased. The study of the formation of a conditioned passive avoidance reflex can be considered not indicative, since two rats from the experimental group and one rat from the group of sham-operated animals did not enter the dark compartment of the installation and did not receive training. In the test for anhedonia, the rats of the experimental group showed a decrease in the consumption of sucrose as compared with the animals of the comparison groups. On histological preparations of the brain at the injection site, the formation of a glial-macrophage "shaft" (hematoxylin-eosin staining) is observed. When analyzing the MRI images, it was proved that the injection was made precisely in the hippocampus of rats. Conclusion: Based on the results of the work, it can be concluded that this method of modeling depression is applicable in fundamental research, since the introduction of lipopolysaccharide into the hippocampus causes neuroinflammation in rats, and as a result, a depression state, and can be used to study the antidepressant activity of new drugs. This work was carried out with the financial support of the Russian Science Foundation grant No. 21-73-20250.

The role of hypoxia in the integrity of the genetic apparatus and the formation of memory in drosophila in the paradigm of conditioned reflex suppression of courtship

M.E. Lobashev and V.В. Savvateev in 1959 obtained unique data on the expansion of the adaptive capabilities of the organism when training the properties of higher nervous activity by the formation of conditioned food reflexes to stimuli that exhaust the nervous system. Apparently, the formation of a conditioned connection help to overcoming stressful effects, adaptation to restrictive conditions, and changes in the functioning of the nervous system. To test this assumption, the influence of stressful influences hypoxia on learning and memory of Drosophila in the paradigm of conditioned reflex suppression of courtship was studied. The results were obtained on the enhancement of the ability to learn under hypoxic exposure. These experimental conditions did not affect memory formation. The effect of hypoxia on chromosomes through the formation of double-stranded breaks was revealed. The data are discussed in light of the relationship between neuroplasticity processes and mechanisms of adaptation to stressors.

ДОСВІД ТА ПЕРСПЕКТИВИ ЗАСТОСУВАННЯ БІОТЕХНІЧНИХ СИСТЕМ У ЗБРОЙНИХ СИЛАХ УКРАЇНИ

This paper considers the experience in creating biotechnical systems and prospects for their use for the needs of the Naval Forces of the Armed Forces of Ukraine. A wide range of tasks that face this Service of the Armed Forces of Ukraine make it necessary to introduce new scientific approaches to their solution. One of the directions for solving these problems in offshore areas is the creation of new promising marine BTS, which involve specially trained marine animals. One of the directions for solving these problems in sea areas is the creation of new promising marine biotechnical systems, which will include specially trained marine animals. Marine animals can be guaranteed to search for, lift underwater objects, provide assistance to divers during underwater operations, carry out exploration and mining of ships and hydraulic facilities, and other tasks. Most of the marine animals known to mankind cannot be trained and they will not be able to fully work as part of biotechnical systems. That is why, in our opinion, the scale of future scientific research on this topic is very impressive. Marine mammals show a friendly attitude towards people, they are well tamed, they quickly get used to conditions of detention in captivity, to a long diet and a change in diet. They show high abilities for learning, for the formation of stable conditioned reflexes and complex forms of conditioned behavior. Thus, we have come to the logical conclusion that, in addition to dolphins, other marine biological objects can be promising species of marine animals that can be involved in work as part of biotechnical systems. The article gave specific recommendations regarding the ways of creating and developing domestic Naval biotechnical systems for the needs of the Naval Forces of the Armed Forces of Ukraine, as well as the activation of existing and known components. Keywords: marine animals, marine bioobject, biotechnical systems, technical systems, Naval Forces, Armed Forces of Ukraine

Influence of PLL treatment on the long-term memory formation in Helix mollusk

Relevance. The studies of the epigenetic mechanisms of long-term memory formation (LTM) has attracted the attention of many world leading laboratories since gained knowledge can be applied to correct cognitive impairments. miRNA dependent suppression of gene expression is the most complicated step in the epigenetic regulation, associated with a huge number of miRNAs (tens of thousands) and the diversity of their targets, thus the knowledge of miRNAs functions during LTM is still very fragmented.
 Aim. The aim of this study was to investigate the involvement of miRNAs in the formation of long-term memory using the model of the food aversion conditioned reflex development in the mollusk Helix. Prevention of the formation of mature miRNAs via Poly-L-lysine hydrobromide (PLL) treatment inhibitor of Dicer activity was used as the main approach.
 Materials and methods. PLL was injected into animals during training, or 1, 3 or 5 hours after training. Success of the formation of conditioned reflexes was tested 72 hours after training.
 Results. There was a significant deterioration in LTM in animals with injected PLL 1 and 3 hours after training procedure compared with trained animals that were not injected with PLL. The treatment with PLL during training, or 5 hours after training, had no effect on LTM.
 Conclusion. Treatment with PLL, inhibitor of miRNA biogenesis disrupts formation of the food aversion reflex in Helix. Thus, miNRAs are involved in the LTM formation on Helix. Impaired expression of miRNAs is critical for the long-term memory formation if occurs in the intervals of 1 to 3 hours after training. We can recommend PLL for the investigations in the area of the epigenetic mechanisms of long-term memory.

Ivan Pavlov: the Person Through the Prism of Scientific Achievements

Ivan Petrovich Pavlov – the oustanding scientist, pride of physiological science, «the first physiologist of the world» as have named his colleagues on one of the international congresses. The Nobel Prize has been awarded him, he have selected the honorary member of 130 academies and scientific organizations. «It is a star which shines the world, throwing light on yet not experienced ways», - Gerbert Wells spoke about him. Pavlov count the founder of science about the higher nervous activity. The scientist has created the greatest inRussiaphysiological school and has made a number of essential opening in the field of regulation of digestion. In XX century began a new stage developments of physiology which characteristic feature transition from narrow understanding of vital processes up to synthetic was. Huge influence on development of Pavlov's physiology and have made his schools on physiology of the higher nervous activity. Opening by Pavlov of a conditioned reflex has allowed to start on an objective basis studying mental processes which underlie behaviour of animals and the person. Pavlov's laws of formation and braking of conditioned reflexes are established, the physiology of analyzers, types of the higher nervous activity, are revealed features of infringement of the higher nervous activity at experimental neurosises, the brain theory of dream and hypnosis are developed, doctrines about alarm systems are incorporated. Works Pavlov have created the materialistic base to the following studying the higher nervous activity, they give a nature-scientific substantiation of the theory of display.

Nootropic effects of bis(citrato)germanates (stannates) with different metals (Mg, Co) in their structure

Aim. Nootropic effects of bis(citrato)germanates (stannates) with different metals (Mg, Co) have been investigated in this article. With this aim the peculiarities of conditioned reflex formation as well as short- and long-term memory manifestations under the influence of the investigated coordinative compounds have been studied for 256 rats with the help of pathophysiological and pharmacological methods.Methods and results. It has been shown that stannates influence on the development of active avoidance conditioned reflex as well as on the manifestations of mnestic functions. It has been found that germacit and gercocit induce positive nootropic effects that occur in case of low dose drugs administration and are characterized by relief of conditioned reflex formation and by short- and long-term memory improvement at the same time.Conclusion. Stanmacit and stancocit also have nootropic effects that dependent on dose and are characterized by nootropic effect during administration in low doses and by amnestic effect at doses starting from 1/40 LD50. This indicates that stannates show nootropic activity.

Levels of Neuroactive Steroids in the Brain and Gender-Related Characteristics of the Formation and Extinction of a Conditioned Reflex in Rats

Model experiments were performed to study the gender-related characteristics of the dynamics of sex steroids in the brain during the acquisition and extinction of a conditioned reflex. Before acquisition of conditioned reflexes, females had greater anxiety and fear than males. On formation of the conditioned reflex, there were no significant gender-related differences between males and females, while extinction of the conditioned passive avoidance reaction in male rats occurred 2–3 days more quickly than in females. On acquisition of the conditioned passive avoidance reflex, adult rats showed increases in testosterone content in several brain structures, especially in the hippocampus and frontal cortex, without any change in the plasma level. There was also an increase in the amygdalar estradiol concentration in females, while extinction of the conditioned passive avoidance reaction was associated with increases in estradiol in the hippocampus and cingulate gyrus. There was no change in plasma testosterone, while the estradiol concentration decreased significantly after extinction of the conditioned reflex. The different dynamics of changes in sex steroid levels in the brain and plasma may point to the possibility that they are synthesized in nervous tissue. Correlation analysis supported the suggestion of the selective involvement of testosterone and estradiol from particular brain structures in mediating learning and memory processes in adult male and female rats.

Influence of new antihypoxant πq1983 on mice conditioned reflexes

The dynamic of active avoidance reaction in consist of a defense conditioned reflex after intragastric administration of new selenium-containing metal-complex substances πQ1983 (100 mg/kg) possessing protective action during development of acute exogenous hypoxia in animal have been studied in experiments on mice. Timing data of the active avoidance reaction in experiments on formerly trained mice under action of this substance used in same doze were analyzed. It was established that substance πQ1983 blocks formation of conditioned reflex. In the group of trained mice antihypoxant πQ1983 increases a latent period of the avoidance reaction and decreases the avoidance time. All found effects provided by intragastric administration of the antihypoxant were short-term (15– 20 h) and reversible. The results were compared with effects of antihypoxant amthizole.

Newly revealed range of action in the preparation derinat: Mnemotropic effect

Mnemotropic effect has been revealed in the action of Derinat, a biologically active compound of natural origin, on the formation of conditioned reflexes of active and passive avoidance. Derinat accelerates the elaboration of conditioned reflexes. This effect manifests itself already at initial stages of the elaboration, which resembles the effect produced by nootropics.

Level of neuroactive steroids in the brain and sex-related peculiarities of formation and extinction of conditioned reflex in rats

Sex-related peculiarities of dynamics of brain sex steroids in the process of learning and extinction of the conditioned reflex of passive avoidance have been studied in model experiment. Prior to learning of the conditioned reflex, female rats were found to be distinguished by manifestation of anxiety and fear as compared with male rats. At formation of the conditioned reflex, no significant sex-related differences were detected between males and females, whereas extinction of the conditioned reaction of passive avoidance in males occurred by 2–3 days faster than in females. At learning of conditioned reaction of passive avoidance, in sexually mature male rats there was revealed an increase of the testosterone content in various brain structures, especially in hippocampus and frontal cortex, while its level in blood plasma remained unchanged. Also shown was an elevation of estradiol concentration in female amygdale, whereas at extinction of the conditioned reaction of passive avoidance, a rise of estradiol values was noted in hippocampus and cingular cortex. At the same time, the testosterone level in blood plasma did not change, whereas after extinction of the conditioned reflex the estradiol concentration decreased statistically significantly. Different dynamics of changes of the sex steroid levels in brain and blood plasma can indicate a possibility of their formation in the nervous tissue. The performed correlation analysis confirms the concept of selective involvement of testosterone and estradiol of individual brain structures in realization of processes of learning and memory in sexually mature male and female rats.

The structurally functional organization of cells in respiratory waysto norm and at a pathology

The term the APUD-system represents an abbreviation of four English words: Amine Precursore Uptake and Decarboxylation, these cells designating the basic property: ability to absorb predecessors entered from the outside biogenic amine to subject them decarboxylation with the subsequent formation biogenic amine and hormones. Biologically active substances which are produced by cells APUD-systems, are responsible for formation of conditioned reflexes, stages of memory and a dream, for formation of painful and emotional sensations.

Expression of MAP/ERK kinase cascade corresponds to the ability to develop food aversion in terrestrial snail at different stages of ontogenesis

The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) cascade plays an important role in gene expression regulation during memory formation in both vertebrates and invertebrates. MAPK/ERK regulates gene expression through phosphorylation of transcription factors binding to the regulatory elements SRE and CRE of target genes. Previously we reported that juvenile snails Helix lucorum differ from adult animals in a spectrum of transcription factors binding to DNA regulatory elements SRE and AP-1. In this study we analyzed the expression and activation of MAPK/ERK in CNS of H. lucorum during formation of the conditioned avoidance reflex at different stages of postnatal ontogenesis. Under conditions of learning, juvenile snails (aged 2–3 months) possessing immature mechanisms of avoidance reflex plasticity showed dramatically low level of phosphorylation and, correspondingly, low activation of MAPK/ERK in comparison to adult animals. Beside this, the MAPK/ERK cascade was not activated after 10 and 60 min after learning in juvenile snails in contrast to adults, while basal expression level of this kinase was similar in juveniles and adults. Low activation of MAPK/ERK cascade can cause a deficiency in phosphorylation of downstream transcription factors binding to SRE and thereby influence the expression of early response genes (particularly, of the family AP-1) and late response genes necessary for cellular and synaptic plasticity. These observations suggest that the MAPK/ERK regulatory cascade plays an essential role in the formation of conditioned avoidance reflexes in Helix. Low activation of this cascade might be one of the reasons for deficiency of long-term memory formation during avoidance learning in juvenile animals.

Interaction of total blood calcium levels and brain catecholamines during the formation and reinforcement of memory traces in hypoparathyroidism

Interactions between the total blood calcium level and catecholamine contents in limbic brain structures during the formation and extinction of a conditioned passive avoidance reflex were studied in rats with hypoparathyroidism. Impairments of calcium support for the processes of conditioned reflex activity were seen after removal of the parathyroid glands. Animals with hypoparathyroidism not only showed changes in basal dopamine and noradrenaline levels in limbic structures, but also impairments of catecholamine dynamics during the acquisition and forced extinction of a conditioned passive avoidance reflex. These results demonstrate changes in the functional dynamics of the dopaminergic and noradrenergic systems of the brain in conditions of abnormal calcium homeostasis in the body, which underlie abnormalities of conditioned reflex activity and the acquisition of the adaptive behavioral strategies.

Possible molecular-cellular mechanisms of the regulation of gene expression during learning.

This study is an analysis of the regulatory mechanisms of plasticity. The first part provides a short review of the role of DNA-binding transcription factors in possible regulatory pathways and their activity in the mechanisms of plasticity. Our own data obtained in studies of the molecular mechanisms underlying the formation of conditioned defensive reflexes in Helix are then presented. These studies show that formation of defensive types of plasticity in Helix is accompanied by serotonin-induced translocation of a protein with Rf 0.58 and increases in G-protein activity, protein kinase A activity, and expression of the c-fos gene. Transcription factors CRE and AP-1 probably have roles in the learning process. Gel shift assays demonstrated the existence of transcription factors of the CRE and AP-1 families in adult snails. In juvenile snails, which were unable to form defensive types of plasticity, the serotonin protein with Rf 0.58 (the learning "marker") was absent from and was not induced in the CNS. Gel shift assay results also showed that transcription factors of the AP-1 family were not present and were not induced by serotonin or the protein kinase A activator forskolin, though these snails had significant levels of CRE transcription factors. Serotonin and forskolin increased the DNA-binding activity of CRE in juvenile Helix. The lack of activity of transcription factors of the AP-1 family in juvenile snails may explain their inability to development sensitization and conditioned defensive reflexes.