REM SLEEP AND DREAMS AS MECHANISMS OF THE RECOVERY OF SEARCH ACTIVITY

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Publication Date:
February 28, 2013

Vadim S. Rotenberg

IN: "The Function 0f Dreaming"
edited by ALAN MOFFITT, MILTON KRAMER and ROBERT HOFFMAN, 1993

The present chapter develops and deepens the basic propositions of the conception of search activity (Arshavsky and Rotenberg, 1976; Rotenberg and Arshavsky, 1979a; 1979b; 1984; Rotenberg, 1982; 1984), integrating the character of the subject's behavior in ordinary and stressful situations, the body's resistance to disease and stress, and the functional designation of REM sleep.

No complex system can be explained by the specific features of its elements. On the contrary, the system determines the function of the elements. This proposition is particularly appropriate when applied to living systems. It follows from this proposition that the departure point in the study of highly organized biological systems, animals and humans, should be their integral behavior and the psychological activity that regulates it. The character of integral behavior determines the state and function of individual physiological systems. This is particularly true of the function of REM sleep and dreams, because any conception purporting to explain their functional relevance should be psychophysical in its nature (i.e., consider both the physiological and the psychological processes occurring in REM sleep) and should apply equally to humans and higher mammals. Such a conception can be constructed only with due account of the specific functional features of behavior, because the general strategy and basic tendencies of behavior determines the correlation between the various functional systems of the organism designed to ensure this behavior.

An adequate behavior classification should meet the following requirements: (1) the types identified on its basis should be relatively easy and reliably determined in simple experiments; (2) it should not be excessively detailed. Although detailed classification systems create greater accuracy and subtlety of behavior description, a more important factor gets lost, specifically the correlation with the physiological andbiochemical changes in the organism. Biological systems are less differentiated than psychological systems. Therefore not every psychologicalstate can be correlated with a strictly definite and unique physiologicalpattern. On the contrary, similar biological changes may correspond todifferent behavioral forms and psychological states.

The author and his colleague have proposed a new behavioral classification satisfying these requirements on the basis of their own systematic research using both animals and humans (Arshavsky and Rotenberg, 1976, 1978; Rotenberg, 1984). This classification is based on theprinciple of biological relevance of search activity, which influences thesuccess of the subject's activity in general and the body's resistance tostress, diseases, and various other harmful factors.

By search activity is understood activity designed to change the situation or the subject's attitude to it in the absence of a definite forecast ofthe results of such activity (i.e., in the case of pragmatic indefiniteness),but with constant monitoring of the results at all stages of activity.

This definition makes it clear that certain behavioral categoriescannot be classed with search behavior. This primarily applies to allforms of stereotyped behavior having a quite definite forecast of results.For example, panicky behavior at first glance may seem to imitate searchbehavior but differ from it by the disturbance of the feedback betweenthe activity and its regulation. Really, during a panic the results of theactivity are not considered at any stage and cannot be used for the correction of behavior. No line of activity can be traced to its conclusionand panicky behavior easily becomes imitative, approaching stereotyped behavior. Finally, the antipode of search behavior is the state ofrenunciation of search, which in animals may assume the form of freezing or imaginary death.

Search behaviors in animals are categorized as all types of activedefense behavior (both aggression and active avoidance) as well as theactive self-stimulation of the brain zones of positive reinforcement. Such self-stimulation is a complex multicomponent behavior, which includesappetence, aversion, and search activity proper (Grastyan, 1976). It has been shown that self-stimulation is obtainable from the same brain structures whose forcible stimulation creates orientative-exploratory behavior; the duration of self-stimulation correlates with the manifestness of the general exploratory reaction of the animal being stimulated(Schiff, Rusak, and Block, 1971); self-stimulation is in competitive relations with stereotyped behavior (Wauquier, 1980), and teaching self-stimulation to dog pups prompts them to develop search behavior (Kassil and Vatayeva, 1981). Naturally, search behavior also includes orientative-exploratory behavior, which particularly often manifests itself in an open-field test: the more manifest the exploratory behavior, the more frequently the animal comes out into the open-field center.

In many mammals (cats, rats, etc.) the electrophysiological correlate of search behavior is synchronous high-amplitude theta-rhythm of the hippocampus. It regularly accompanies search behavior (Simonov, 1981). None of the existing hypotheses pertaining to the functional relevance of this rhythm contradicts the following assumption: search activity plays a great role in teaching, in directed attention, in behavior planning, in the organization of arbitrary motor acts, and in the selective memorizing of information (Rotenberg, 1984). Nevertheless, the identification of purely behavioral criteria of search presents certain difficulties. At first glance, an animal's search activity can be reflected in its motor activity. Indeed, search frequently manifests itself in exploratory behavior. But the notion of "search" is broader than the notion of "exploratory behavior," and identification of search behavior with motor behavior may lead to serious errors.

First, search can proceed without any manifestations in the motor sphere if the movements pose a threat or, according to the conditions of the experiment, involve a punishment. The temporary inhibition of overt behavior at the encounter with a new, surprising, or emotionally significant situation is a very well-studied phenomenon (Gray, 1982; Morrison, 1982). During such inhibition intense reappraisal of the situation proceeds; that is, search behavior. Passive avoidance works. For example, in the Porsolt Test intense search activity characterizes the rats that find the shallowest place in the pool sooner than others, where they can maintain immobility resting on their tails. Conversely, less adapted rats inclined to panicky behavior spend a much longer time performing exhausting movements around the pool (Hawkins et al., 1980). This unproductive chaotic activity appears to be inversely correlated with search activity. Moreover, exclusive orientation to motor activity without consideration of the entire context of the situation and the research conditions frequently leads to the erroneous identification of such salutary passive avoidance with the reaction of surrender (renunciation of search) of the freezing type.

Tracing the boundaries of search activity in humans is a still more complex problem, where psychological processes unaccompanied by overt behavior play a still greater role. Among humans, search manifests itself in the planning, fantasizing, and rethinking of the situation. In addition, the hallucinatory emotional experiences and delirium of psychic patients are classed with perversely oriented but very intensive search activity (Rotenberg, 1982). Therefore, in humans, just as in animals, it is simpler to indicate states and forms of behavior that undoubtedly do not contain the search activity component. Into this category falls stereotyped behavior with an exact forecast of results. However, it is difficult to determine such behavior operationally and separate it from the entire behavior context. The state of renunciation of search can be identified with greater definiteness. Above all, this includes various forms of depression and the reaction of surrender, which Engel and Shmate (1967) have called give-up-giving-up. Within the same category lies unproductive, neurotic anxiety similar to the freezing reaction (anticipation of a catastrophe) in animals. In keeping with psychodynamic conceptions, the author assumes that neurotic anxiety is a consequence of the repression of an unacceptable motive from consciousness. The repression can be regarded as a purely human variant of renunciation of search of the modes of realization of the unacceptable motive in behavior and modes of integration of it with other, realized behavioral orientations. The difference between productive emotional tension (the normal anxiety of a healthy individual in a state of stress), instrumental in mobilizing all psychological and physical resources to overcome obstacles, and unproductive emotional tension (in particular, neurotic anxiety) that hampers successful activity is determined by the presence or absence of search activity in the structure of emotional tension.

Search and renunciation of search influence the body's resistance to stress and other harmful factors in an opposite manner. The author's research (Rotenberg and Arshavsky, 1979a; 1979b), as well as publications of many other authors (Simonov, 1981; Seligman, 1975; Anisman, Ritch, and Sklar, 1981), has shown that search behavior raises the body's resistance and stress resistance and blocks the development of stress diseases and artificially induced pathology such as experimental epilepsy, anaphylactic shock, hypertension, myocardial infarction, cardiac rhythm disturbances, Parkinsonlike neuroleptic syndrome, the implantation of malignant tumors, addiction to alcohol, and so on. Renunciation of search furthers the development of all these forms of pathology, reduces the body's biological resistance and may cause death. Appropriate experiments on animals are extensively described in the author's previous publications (Rotenberg and Arshavsky, 1979b; Rotenberg 1984). Therefore, this chapter will outline similar facts obtained in research on humans.

More and more new facts show that the emergence and development of psychosomatic diseases, including ischemic heart disease, myocardial infarction, malignant tumors, and duodenal ulcers very frequently follow overt or covert depression (Glass and Carver, 1980; M. Weiss, 1985; justice, 1986; Appels, 1979). Both constructive aggressiveness analogous to creative activity and destructive aggressiveness directed outward reduce the risk of psychosomatic diseases, whereas the deficit of aggressiveness corresponding to the notion of "renunciation of search" increases this risk (Ammon, Ammon, and Griepenstroh, 1982). This stands in good agreement with data about the competitive relations between depression and aggressive behavior (Pittman and Pittman, 1979; Harrel and Hayness, 1978) and with experimental data showing that aggressive behavior during stress prevents the development of somatic disturbances U. Weiss, 1977). Undesirable and uncontrolled changes in life further the development of somatic diseases (Mullen and Sulls, 1982). The absence of control over the situation is one of the key factors in the development of learned helplessness (Seligman, 1975); that is, in renunciation of search. Individuals who withstand emotional stress very well and do not fall ill afterward exhibit more constructive relations with the world and clear aims. They are fighters having a pronounced motivation of achievement (Kobasa, 1979). At the same time, the impossibility of coping with a stressful situation leads to the inhibition of active behavior (i.e., to a renunciation of search) accompanied by the activation of the hypothalamus-pituitary body-adrenal cortex system. Such a combination of pronounced stress with the blockade of active search behavior soon leads to the development of peptic ulcers (Kukleta, 1979). This is the watershed between stress and distress (Selye, 1974). The latter stems from a loss of control over the situation, a drop in resistance, and relative predominance of the activity of the pitu itary body-adrenal cortex system (Henry and Stephens, 1977). In the author's opinion, the transition of stress as a reaction of increased mobilization geared to overcome difficulties of life into distress leading to illness and death reflects a qualitative change of the character of behavior and a replacement of search activity with a state of renunciation of search (Rotenberg, 1984).

The body's resistance declines in the case of renunciation of search in stressful situations unacceptable to the subject and also in the case of any weakening of search behavior. Individuals with high indices on the anhedonia scale (apathy and lack of initiative) die a natural death earlier than individuals with low indices on this scale (Watson and Kugala, 1978). On the other hand, even prolonged and very intense stress unaccompanied by a reaction of surrender not only does not reduce the body's resistance, but may even raise it. For example during the Second World War participants in military operations or individuals who did hard work in the rear showed a drop in the rate of disease compared to the prewar period (Natelson, 1983). Furthermore, concentration camp inmates who lived to see their release (in the main, people who retained the ability to resist, even if only inwardly) exhibited the disappearance of the symptoms of their precamp psychosomatic diseases.

Thus, the old dilemma, whether stress is useful or harmful is solved depending on the degree of manifestness of search activity during stress. But if search activity is of such great biological relevance and renunciation of search leads to illness and death, why has the latter regressive behavior survived in the course of evolution and what makes it emerge?

All higher mammals including humans, at the early stages of ontogenesis inevitably experience helplessness determined by the relatively slow development of the central nervous system and all mechanisms (nervous, hormonal, and vegetative) that ensure subsequent search behavior. Naturally, during the early stages of ontogenesis such a state cannot be called renunciation of search. It is normal and inevitable and the only accessible form of a defense reaction for an immature organism. The organism thus acquires an early experience of passive reaction, an experience of helplessness. Both this experience and the ways to overcome it are of colossal relevance to the individual's entire subsequent life. In the case of a correct attitude of the primary group, above all the mother, this early experience of helplessness can be successfully and painlessly overcome. The child, gradually feeling constant support will pass on to increasingly active behavior. The child's first steps toward the development of search activity must proceed under the constant protection of the mother who helps the child overcome fear of new situations, fear that consolidates the experience of passive reaction. All injuries in early childhood, from the physical separation from the mother to insufficient emotional contact with her and the feeling of insufficient protectedness due to strained relations between the parents can consolidate the experience of primary helplessness and fear of the newness of situations and of the need for search behavior. The imprinting mechanism may lead to the development of a state of renunciation of search in an adult, especially if the emotional problems encountered in some way resemble conflicts of early childhood. Thus readiness for the development of neuroses and psychosomatic illnesses is formed. It is exactly from these general biological positions, the relations between early helplessness and the formation of search activity, that the author proposes considering the Freudian theory of the role of early psychotraumatizing situations in the entire subsequent development of the individual. Regressive behavior in the cases of neuroses and psychosomatic illnessses according to Freud is indeed a regression towards a biologically earlier state of passiveness and helplessness that assumes the form of renunciation of search. However, as the physiological mechanisms of search behavior mature, the child should gain increasing independence and be induced to practice independently overcoming obstacles. The very fact of such overcoming, of the broadening of possibilities, exercises a powerful reinforcing effect, developing a search requirement in the child. The existence of an independent search requirement is proved by experiments in which animals are placed in artificial "ideal" conditions in which all their primary requirements ('m food, partners, and play) are satisfied and yet they make efforts to escape from this "paradise" into an unknown and potentially dangerous expanse in spite of their fear of it.

If an independent requirement for search activity is not shaped, in time throughout later life search behavior may emerge only as a forced reaction to complex situations, will be colored by negative emotions, and may fairly easily yield to the state of renunciation of search. At this early stage two opposite conditions may equally suppress the development of the search requirement, constant (invariable) negative reinforcement and invariable positive reinforcement. In the former case any activity, above all search activity, is depreciated in the subject's eyes and perceived as senseless and leading to punishment. The child soon learns that search is dangerous. In the latter case, when all desires are satisfied immediately and without sufficient effort, the search activity requirement is not formed because it is superfluous. If the search requirement is not sufficiently developed then subsequently at maturity even moderately stressful situations and minor obstacles to the achievement of an aim may cause a reaction of surrender.

However, a search requirement does not guarantee the stable preservation of search activity either. Even when this requirement is pronounced, renunciation may occur if failures come in close succession and acquire greater relevance than the aims the child strives to achieve and are greater than the positive reinforcement from search itself. On the other hand, the more pronounced the search requirement and the higher the search activity, the more difficult it is to suppress and evolve learned helplessness because search itself, irrespective of its final results, can come to represent an independent value and bring pleasure, as in the case of creation. It can be assumed that in the animals and humans in which learned helplessness can never be evolved (according to Seligman, this category accounts for 20 percent among dogs) early experience has ensured a high level of search activity.

Renunciation of search is also possible when the status quo fully satisfies the subject. The basic aims are achieved without search behavior on the basis of developed behavioral stereotypes and search even poses the threat of a loss of what is already achieved. In these conditions the subject is motivated to make no search. If such a motivation emerges in an individual with a high original search requirement, he or she will develop an inner conflict. The search requirement will be frustrated, and if no modes of realization are found for it, the mounting inner tension may result in psychological and somatic disturbances. Perhaps this is the mechanism of the diseases of achievement that emerge on the crest of success after the individual abruptly breaks off the search efforts.

When the search requirement is not great, the cessation of search activity is not perceived subjectively as a stress creator. Furthermore, such a cessation may be accompanied by a feeling of relief or relaxation. However, the body's resistance to various harmful factors then decreases and the organism becomes more vulnerable. In addition, easy success, taken as natural, decreases the productivity of efforts (Tiggeman, 1981).

The author's psychological research, carried out jointly with I. S. Korostelyova has confirmed these theoretical conceptions, supplementing them with concrete data. It was established that in the case of systematic negative r 'einforcement a serious factor of the risk of prompt surrender is the predominance in the individual of the fixation on the obstacle as a reaction to frustration (Rosenzweig, 1935) combined with a low aggregate motivation of achievement (Heckhausen, 1977). In healthy subjects prolonged negative reinforcement changes the type of reaction to frustration in the direction of an increase of fixation on the obstacles. In psychosomatic patients characterized by gastric and duodenal ulcers and malignant tumors this type of reaction, even outside emotional stress, is much more pronounced than in healthy individuals. The dominance in the achievement motivation structure of the motive of avoidance provokes greater emotional tension in the course of negative reinforcement. This may also play a serious role in bringing'about a renunciation of search. The similar level of the two motives (the motive of the achievement of success and the motive of the avoidance of failure) create prerequisites for an inner motivational conflict and, combined with a low aggregate motivation, determine tendencies toward early attempts to stop activity. The decline of the ability to forecast results and the insufficiently expressed striving to use various means of achieving an aim, coupled with an inner motivational conflict, create conditions for a renunciation of search. Any impossibility to satisfy a powerful need eventually entails a renunciation of search and illness (see McClelland, 1982).

At the same time, the greatest resistance to the development of a reaction of surrender during the stress due to negative reinforcement is found in subjects with a predominant desire to overcome obstacles. Combined with a high aggregate motivation for achievement, such a desire to overcome obstacles can be assessed as a manifestation of a high degree of expression of search activity, especially if the motive of the achievement of success clearly dominates the motive of the avoidance of failure.

The question of the physiological mechanisms of search behavior has no final solution so far. Undoubtedly, an appreciable role in the brain system regulating these behavioral forms is played by the hypothalamus (Rotenberg and Arshavsky, 1979b) and the hippocampus (Simonov, 1981). Apparently, the frontal brain lobe is of essential importance. The biochemical mechanisms of search behavior are also studied insufficiently but there are reasons to believe that the brain's catecholamine system is closely connected with search behavior. Learned helplessness accompanied by somatic disturbances emerges when the brain catecholamine level drops (Seligman, 1975). An artificial reduction of catecholamine levels by tetrabenazine speeds behavioral depression whereas the prevention of depletion by MAO inhibitors raises stress resistance, restoring the animal's ability for an active reaction to stress (Katz, Roth and Carrol, 1981). The neuroleptic blockade of the postsynaptic receptors of the catecholamine system also weakens search behavior (Rotenberg, 1988a; Wauquier, 1980). In animals that cannot control the stressful situation the brain norepinephrine level drops particularly low and they show the greatest distress (Lehnert et al., 1984; Kohno et al., 1983). Substances blocking brain epinephrine metabolism impede the teaching of complex avoidance to an animal (Archer, Jonsson, and Ross, 1985). Finally, the locus coeruleus plays a major role in the organization of various forms of search behavior (Paul and Van Dongen, 1981).

On the basis of all the preceding facts the following hypothesis has been advanced (Rotenberg, 1984). Search activity can begin in the presence of a certain critical level of the brain catecholamines (in particular, norepinephrine and dopamine) that are utilized in the course of search. Search activity itself, once it begins, stimulates the synthesis of the brain catecholamines and ensures their necessary or even excessive amount. In the case of acute stress it is exactly the rise in the brain norepinephrine content that is connected with search activity (Stone, 1975; Stone and Platt, 1982).

Thus the more pronounced the search activity, the sooner the expenditure of the catecholamines necessary to maintain the search behavior is compensated. The functional task of such a system with positive feedback (the more intense is the search, the more intense the expenditure and synthesis of the catecholamines and the more intense the search) is to support search activity. But if this system is to start working at the very outset, the brain catecholamine level must be above a critical level. If it drops below that level, search behavior becomes impossible.

In a state of renunciation of search this system does not function. Furthermore, in this state that manifests itself in unproductive emotional tension, the catecholamine expenditure climbs possibly due to the drop in its reuptake (as presumably happens in the case of a chronic stress). Thus, a vicious circle forms: renunciation of search, a drop in the brain catecholamine level followed by a deepening of the renunciation of search.

This vicious circle is formed whenever there is a drop in search activity, whatever the reason. This makes it interesting to discuss the ideas of Zuckerman (1984), who assumes that the optimal level of behavioral activation and adaptation corresponds to a moderate activation of the brain catecholamine system. A low level of this system's activity corresponds to primary depression, secondary anxiety, and the inhibition of active behavior.

An excessively high level of activity of the same system corresponds to the anxiety-panic behavior and secondary neurotic depression. Because it is difficult to imagine a depression combined with a high level of activity of the brain catecholamine system, the present author proposes the following modification of this scheme. The activity of the brain catecholan-dne system becomes "excessive" when, and only when, for some reason the subject fails to maintain search behavior, yielding to panicky (stereotyped) behavior. This happens in particular when there is a threat of frustration of vital requirements and fear of the consequences of failure disintegrates all behavior. However, panicky behavior is not search behavior, as shown previously. Consequently, it does not restore the brain catecholarnine level. The expenditure of catecholamines exceeds their synthesis, and eventually there comes a pronounced drop in their levels and a secondary depression develops. The same is characteristic of neurotic anxiety that, just as with panic, is dominated by agitated behavior. In terms of the author's conception, a deficit of search behavior is common to panic, neurotic anxiety, and depression. The difference is that panic and anxiety reflect the process of constant decline of the brain catecholamine level, whereas depression is the result of this decline. Consequently, in the case of any form of renunciation of search, if it is not overcome and does not give way to search behavior by the activation of compensatory mec anisms or a change in life circumstances, eventually depression develops. This proposition is confirmed by clinical observations. The present hypothesis is also supported by the fact that the state of panic is arrested by tranquilizers of the benzodiazepine series to a lesser extent than by tricyclic antidepressants, which block the reuptake of norepinephrine (Shekhan, Ballenger, and Jacobson, 1980). The foregoing makes it clear that the most characteristic aspect of search activity is the biological relevance of the very process of search, whatever its pragmatic results. Search is necessary for the preservation of good health, irrespective of the degree of satisfaction with the situation and the presence or absence of frustration and formal symptoms of stress. Search activity is not a means, but an end. It performs a protective function, even if the search object is unattainable.

Herein lies the basic difference between the conception of search activity and the conception of coping behavior (Coyne and Lazarus, 1980). Herein, too, lies the difference between the conception of search activity and the conception of Engel and Shmale (1967), who focused attention on one pole of behavior; the give-up-giving-up complex. Another difference is the inclusion in search behavior of a wider scope of phenomena than is usually understood by coping behavior, in particular, spontaneous creative activity and orientative-exploratory behavior. It is also of basic importance that, according to this conception, search activity is not only a mechanism of ensuring adaptation, but also a mechanism of the development of the individual, a mechanism of one's self-realization and consequently, an important factor behind the progress of the population as a whole. The elimination of individuals inclined toward renunciation of search maintains search behavior in the population, without which its entire development will stop.

But if search behavior really plays such a vital role in adaptation and development, there must be a fundamental mechanism permitting compensation for the biologically, psychologically, and socially harmful state of renunciation of search and ensuring the restoration of search activity. Such a mechanism is REM sleep and the accompanying dreams (Rotenberg, 1984). Arguments supporting this assertion follow.

First, experiments on animals have shown that the behavioral forms that include a search component (active-defense behavior and self-stimulation) are accompanied by a reduction of REM sleep without its subsequent rebound; that is, there is a drop in the REM sleep requirement (Putkonen and Putkonen, 1971; Cohen et al., 1975). Conversely, the state of renunciation of search, caused by the stimulation of the ventromedial nuclei of the hypothalamus almost doubles the REM sleep requirement and the percentage of this sleep phase in rats (Rotenberg and Arshavsky, 1979a, 1979b). Rats that display low activity in a stressful situation requiring active behavior show a higher percentage of REM sleep and prefer alcohol to glucose. The latter fact furnishes an additional proof of the inclination toward the renunciation of search. The taking of alcohol increases behavioral activity and shortens REM sleep in these animals (Viglinskaya and Burov, 1987). The process of adaptation to a stressful situation gradually shortens REM sleep (Sinton and Jouvet, 1983), which enables these authors to regard the lengthening of REM sleep at the encounter with a threatening situation as part of the coping strategy.

In top-class athletes REM sleep grows longer after considerable athletic failures that may cause a reaction of surrender (Rotenberg and Arshavsky, 1979a). On the postexamination night REM sleep lasts longer only in students who show signs of unproductive emotional tension. Specifically, the vegetative and electromyographic indices of emotional tension remain high after the examination and intellectual problems are solved hastily and with mistakes. After a sleep with an extensive REM phase the signs of such tension disappear (Rotenberg and Arshavsky,1979a).

The subjects in whom REM sleep lengthens in the course of intensive learning of a foreign language did not display mounting stress (De Koninck et al., 1975). REM sleep deprivation exercises a particularly negative effect on the solution of creative problems (Lewin and Glaubmann, 1975).

Second, the REM sleep requirement, determined by the latency to REM sleep and by an increase of the REM sleep period in the first cycles, is increased in the cases of depression (Reynolds and Kupfer, 1988) and neurotic anxiety (Greenberg, Pearlman, and Campel, 1972). The REM sleep period is longer in long sleepers (Hartmann, 1973). Long sleepers are characterized by a higher sensitivity level, an inclination toward subdepressive reactions and a rise in the MMPI clinical scales compared to short sleepers (Wagner and Mooney, 1975). High sensitivity to anxiety sources and a disposition to depressive reactions is also characteristic of narcoleptic patients who show a constantly high REM sleep requirement (Beutler et al., 1981).

At the same time, highly reactive individuals with a pronounced type A pattern show a shorter total sleep duration (Hicks et al., 1980), the latter exhibiting the closest correlation with the REM sleep duration.

REM sleep, just like total sleep duration, abruptly shortens in a state of high creative activity as well as in pathological states with high but unproductive search activity such as mania and acute psychosis with psychoproductive symptomatics (Mendelson, Gillin and Wyatt, 1977). The author's research carried out jointly with I. S. Korostelyova and V. V. Kulikovsky also confirms these regularities. The percentage of REM sleep in subjects working in strained conditions of high responsibility negatively correlates with the magnitude of pure motivation of achievement (by Heckhausen, i.e., with the difference between the motive of the achievement of success and the motive of the avoidance of failure). The closer the indices of these motives, the greater the REM sleep percentage. REM sleep percentage also directly correlates with the degree of expression of trait anxiety and the motive of the avoidance of failure, with the presentiment of failure in activity and with the need to avoid failure. It has been shown earlier that the conflict of motives and the relative predominance of the motivation of the avoidance of failure predispose toward a reaction of surrender in the case of prolonged negative reinforcement. Consequently, psychophysiological research confirms that in the case of a combination of factors capable of bringing about a state of renunciation of search there is a compensatory rise in the REM sleep requirement. The ratio of the REM sleep duration in the first two cycles to the delta-sleep duration can be regarded as a quantitative indicator of the degree of expression of renunciation of search. In the case of depression and neurotic anxiety this indicator rises and in the case of productive emotional tension it drops (Rotenberg, 1980; Rotenberg and Arshavsky, 1979a).

Third, the hippocampal theta-rhythm, typical of search behavior in waking, is found during REM sleep. Correlations between the degree of expression of the theta-rhythm in waking and in sleep fully confirm the author's hypothesis: the more the theta-rhythm is found in waking, the less it is expressed in REM sleep. Furthermore, if in the course of REM sleep deprivation it becomes possible to induce active-defense or exploratory behavior characterized by the hippocampal theta-rhythm, the subsequent compensatory REM sleep "rebound" may not set in at all; that is, the REM sleep requirement declines (Oniani and Lortkipanidze, 1985). In the absence of the hippocampal theta-rhythm in the course of REM sleep deprivation there is a great REM sleep "rebound" in the restorative sleep. This suggests that the role of REM sleep in the compensation for the state of renunciation of search is largely determined by the intensity of search activity during dreams.

In agreement with this conception is the fact that during the early stages of ontogenesis of newborn babies, in the absence of prerequisites for overt search behavior the greatest proportion of sleep is active sleep whose many indicators resemble those of the REM sleep of adults. Research shows that the monoamine reuptake blockers sharply suppress active sleep in early ontogenesis and these animals, when adult show longer REM sleep than controls as well as a higher amplitude, of the hippocampal theta-rhythm in REM sleep (Mirmiran et al., 1981). These animals display signs of higher emotionality (fear) in waking, faster learning of passive avoidance, and weaker sexual and exploratory behavior. It can be assumed that the suppression of activated sleep in early ontogenesis for a long period reinforces the position of helplessness, natural at this stage, which manifests itself in the behavior of an adult. The REM sleep increase reflects the insufficiently successful tendency to overcome this position.

Fourth, one of the strongest arguments in favor of this hypothesis is the results of the investigation of animal behavior during REM sleep without muscular atonia, the result of a local impairment of the locus coeruleus (jouvet and Delorme, 1965; Morrison 1982). Meticulous analysis has shown that the most common component of this behavior, orientative, search, attacking, or agitated is search activity as understood by the author. Simultaneously, exploratory open-field behavior is activated in waking. From these facts Morrison draws the conclusion that the impairment of the locus coeruleus disturbs the brain system that in a normal state inhibits locomotor behavior in an emotionally significant situation. In the author's view, this phenomenon can be more accurately described as the inhibition of the overt locomotor manifestation of search activity. Thus, these experiments furnish direct proof of pronounced search activity in REM sleep. Also, it is possible that the increase of the locomotor component of search behavior in waking after destruction of the locus coeruleus is at least partly connected with partial REM sleep deprivation because animals that "participated" in their own dreams wake up during REM sleep more often than the controls. Similarly, motor agitation after REM sleep deprivation is a very wellknown fact.

Fifth, the psychological analysis of the processes taking place in human dreams is also consistent with the hypothesis. Currently the best developed and argued conception of the functional relevance of dreams has been proposed by Greenberg (1987). According to this conception, dreams integrate incoming information with previous experience in such a way as to help the subject with the current situation. After successful dreams the subject's position in relation to the complex situation in waking grows stronger, and after unsuccessful dreams it weakens. In Greenberg's opinion, there is a direct connection between the content of the dreams and the emotional problem that is brought out by psychoanalysis. However, experience shows that this connection is not always so clear. In many cases it can be only a question of analogies. Even in the example cited by Greenberg (1987) this connection is conventional and based on image transformations: the rollback of the car in which the subject climbs a hill in his dreams is, after all, only a conventional analogue of fear of regressive relations of dependence. In their earlier publications Greenberg and Pearhnan (1979) expressed an idea that appears to be broader: in a dream a pressing emotional problem can be substituted for by another, connected with it not so much semantically as by emotional relevance. This substituting problem, unlike the actual one can be solved. However, in that case the operating basis of dreams is not the successful result of the solution of the problem but the very process of solution itself. For what is the sense of solving a conventional problem in dreams if this solution cannot be directly carried over to the actual problem in waking? In the author's terminology, the process of search has its own relevance. Then the concrete problem and its conceptual aspect are inessential: the process of search can be stimulated by problems bearing no relation to reality. All that is important is that the search should not lead to a deadlock and that there should be no renunciation of search in the dreams themselves. In this sense the observations of Greenberg and Pearlman (1979) are of extraordinary importance. They have pointed out that in individuals with disturbed psychological adaptation their dreams show a regularly manifesting reaction of surrender before insuperable difficulties and that there is a certain connection between these reactions of surrender in sleep and in waking. In the author's opinion, this connection consists of the fact that renunciation of search for a solution to a problem situation in dreams not only does not compensate for the state of renunciation of search in waking, but even deepens it. For example, individuals who successfully cope with emotional problems display more pronounced positive motives in the concluding dream compared to those who in such cases exhibit a reaction of depression (Cartwright et al., 1984).

The research of the author (Rotenberg, 1980, 1988b, 1988c) as well as of Cohen (1977) shows that in ordinary conditions individuals having high sensitivity and neuroticism the entire functional REM sleep-dreams system operates with higher tension, showing a higher REM sleep requirement and more saturated and emotionally significant dreams than individuals having low neuroticism. In cases of additional emotional load or after REM sleep deprivation in individuals with a low sensitivity level, the activity of this system rises by way of compensation whereas individuals with high sensitivity frequently exhibit a disruption of adaptation, and the activity of the entire system decreases (reduction of dream recall, awakening after REM sleep, and its shrinkage following more unpleasant dreams than before). The author assumes that it is the result of the extension of the state of renunciation of search to the dreaming process as well.

What presumably are the biochemical aspects of the compensatory, restorative effect of REM sleep on search activity? If search activity is to begin in REM sleep, the level of the brain catecholamines, primarily norepinephrine, must exceed a certain critical value as in waking. In natural conditions, when neurotoxic substances are not used and thus do not destroy the catecholaminergic neurons, the drop in the level of norepinephrine and other catecholamines to a critical level and below is due mainly to a renunciation of search. This means that the latter state begins before the brain catecholamines reach the critical level. Fo REM sleep and dreams this level is presumably lower than for waking. lndi rectly, this assumption is confirmed by the fact that a lower level of cerebral activation in general is sufficient for the effective functioning of image, right-hemispheric thinking than for logical-sign thinking. Dreams are dominated by image thinking (Rotenberg, 1985a; 1985b)., Gaillard (1985) confirms that the realization of REM sleep necessitates a lower activity of the brain noradrenergic system than the realization of waking. Consequently, when in a state of renunciation of search waking changes into sleep, the brain catecholamine level is already too low for the restoration of search behavior in waking (with the preservation of the conditions that have brought about the renunciation of search), but it is still high enough for search to begin in dreams. Furthermore, the transition to sleep points to withdrawal from the situation that caused the reaction of surrender.

This means that there is a temporary removal of the factors that deepen this state and the reserves for search activity are not yet exhausted. Conditions are created for search in REM sleep to perform its compensatory function and for the system with a positive feedback, described earlier, to go into action. Most significant, a compensation of the search activity deficit not only takes place during REM sleep, but also the restoration of the possibilities for this activity during subsequent waking, which is even more important.

With due account of all these circumstances, the plunge into the inner world of dreams in principle may create such optimal conditions for search activity that a mechanism limiting this activity becomes necessary. Otherwise the dreams may, "on the principle of self-repayment," last indefinitely long, hampering the transition to NREM sleep and waking. Gaillard (1985) describes one of such limiting mechanisms-stimulation of alpha-two adrenoreceptors that decrease the ejection of norepinephrine and easily suppress REM sleep. However, waking is suppressed only in the case of much higher doses of stimulators whereas the blockade of alpha-two adrenoreceptors either leaves the REM sleep unaffected or lengthens it much less than waking. REM sleep is much more sensitive than waking to the stimulation of alpha-two adrenoreceptors, and the regulatory mechanism with the participation of these receptors limits the lengthening of REM sleep.

The proposed hypothesis concerning the functional role of REM sleep and dreaming helps explain the following contradiction. It is known that unavoidable aversive stimulation with multiple repetitions during the twenty-four hour period soon leads to a reaction of surrender, causing learned helplessness. In addition, this correlates with the drop in brain catecholamine levels (Swenson and Vogel, 1983; Kohno et. al., 1983; Lehnert et. al., 1984). However, if the same hour-long stress regularly recurs for many days, that is, the stress acquires a chronic character but is limited in time, fairly soon both behavioral and somatic adaptation occur and the brain catecholamine system activity goes back to the original level (Stone and Platt, 1982). Possibly this is due to the fact that in the intervals between the stress stimulation the animal sleeps and the REM sleep performs its compensatory function. The alternative explanation is that in the case of chronic stress the system maintaining the brain catecholamine level reshapes in such a way that the drop of this level immediately activates the feedback system, which stimulates catecholamine synthesis. But if this were really so, after a while the stress impact would immediately have to intensify the norepinephrine ejection. In the meantime, the opposite takes place: norepinephrine ejection increases in the conditions of peace, in the intervals between the stress impacts, whereas during the action of stress itself, however many times it recurs the catecholamine ejection decreases (Stone and Platt, 1982). In terms of the author's hypothesis this is explained as follows: the irremovable aversive stress provokes a reaction of surrender and a drop in the brain catecholamine system activity, and REM sleep in the intervals restores this activity.

Thus, REM sleep requirement rises in the case of renunciation of search in waking and a decline of the brain catecholamine system activity. If the drop in the brain catecholamine level then does not reach a critical point REM sleep grows longer and the search in dreams intensifies. If the brain catecholamine level falls below a critical level due to long and strong aversive impacts, including those preventing the onset of sleep or due to pharmacological interventions the very activation of the compensatory search in REM sleep becomes impossible. The author sees in this the reason for a nonlinear relationship between the REM sleep duration and the dose of preparations that change the brain catecholamine level: a moderate decrease of this level activates the mechanisms starting search activity in REM sleep and lengthening the REM sleep; a rise of this level corresponding to high search activity lowers the REM sleep requirement and leads to its reduction even without the subsequent rebound, and the excessive drop in the brain catecholamine level inhibits search activity in REM sleep and can also cause its reduction. This nonlinear relationship corresponds exactly to the nonlinear relationship between the degree of manifestness of depression and REM sleep: when the leading MMPI scale depression rises from 65 to 75 T points REM sleep grows longer (compared to the magnitude of this scale of up to 65 T points). When the scale score grows further REM becomes reduced (Rotenberg, 1988c). But even when REM duration does not change, REM sleep in fact loses its functional designation and undergoes a qualitative change. The physiological and biochemical mechanisms ensuring the emergence of REM sleep do not fully coincide with the mechanisms ensuring search activity in REM sleep. In dreams, as in waking, the feeling of helplessness and unproductive anxiety begins to dominate, the individual's active position in dreams is absent, the nurnber of dreams recalled decreases, the dynamics of vegetative indices changes (the rise in the pulse frequency in REM sleep and the reduction of the GSR are less pronounced), the heart contraction frequency correlates with the negative emotional experiences in them rather than with the degree of the individual's participation in the dreams, and so forth (Rotenberg, 1988b). Similar qualitative changes in REM sleep and dreams in the cases of depression have been established by Berger, Reimann, and Lauer (1988) and by Escalate (1986). All these changes are signs of the weakening of search activity in REM sleep. This sleep may then become not simply useless, but even harmful: during REM sleep in which the renunciation of search continues the brain catecholamine reserves become further exhausted instead of refilling. This changes REM sleep from a mechanism of compensation into an important rnechanism of pathogenesis (Rotenberg, 1980, 1988b, 1988c). Apparently, a serious role in this functional disturbance is played by the weakening of image thinking (Rotenberg, 1985a, 1985b). Perhaps this is the reason for the positive effect of the deprivation of REM sleep (and of sleep in general) in the case of some forms of depression and Parkinsonism (Vogel, 1979; Wehr and Sack, 1988). Such deprivation breaks the vicious circle when the state of renunciation of search, having developed in waking, deepens still more in REM sleep.

The problem of the functional adequacy of the REM sleep-dreams system is among the basic problems in the search activity conception. The ideas about the role of functional defectiveness of this system in the mechanisms of the development of neuroses, depressions, and psychosomatic disturbances, first advanced by the author (Rotenberg and Biniaurisvili, 1973), have been gaining increasing confirmation in recent research. For instance, Berger, Reimann, and Lauer (1988) have shown that in healthy individuals acute and brief emotional stress does not change the sleep structure (duration of the REM sleep and the latency of the first REM sleep episode) if there is a change in the character of dreams in the first REM sleep episodes. These become more alarming and aggressive and are characterized by the dreamer's more active participation in his or her own dreams compared to the research outside stress. However, in the last REM sleep episode the mood restores, which apparently shows the compensatory-adaptive role of the REM sleep processes. Yet qualitative changes in REM sleep alone may be found to be not enough. In subjects who react to stress by unproductive anxiety after stress the duration of the REM sleep increases, above all, in its first two cycles (Rotenberg and Arshavsky, 1979a; Rotenberg and Alexeyev, 1981). If the lengthening of the REM sleep is not enough to compensate for its qualitative inadequacy, there is a growing threat of psychosomatic or psychological disturbance. This should draw attention to the fact that in patients with cardiac pathology who are administered intensive therapy the increase of the phasic oculomotor activity in the REM sleep takes place before an increase in the delta-sleep duration (Broughton and Baron, 1973); that is, the restoration of the functional adequacy of the REM sleep is found to be a major adaptation factor. The positive curative effect in the cases of depression is yielded not by the deprivation of REM sleep as such, but by the deprivation of functionally inadequate REM sleep. This formulation of the question makes it clear that the direct comparison of the results of REM sleep deprivation in the cases of depression with the effect of REM sleep deprivation in animals is not justified. The well-known proposition that REM sleep deprivation in animals activates their behavior needs serious refinement. First, such activation is not observed in all forms of deprivation. If the deprivation follows a method other than that of Jouvet (i.e., is not administered on a water-surrounded platform) but in comfortable conditions by the direct stimulation of the reticular formation of the truncus cerebri (Rotenberg, Kovalzon, and Tsibulsky, 1986) or if active-defense and orientative behavior is provoked at the deprivation (Oniani and Lortkipanidze, 1985), there is neither a pronounced behavioral change nor distress symptoms. If the deprivation follows the Jouvet method the activating effect on behavior is observed only at the relatively early deprivation stages when the animal was removed from the platform and placed for some time in a substantially less stressful open-field situation or in the conditions of self-stimulation. After longer deprivation periods animals display a drop in their activity and physical resistance. They may even die. Molienhour, Voorhees, and Davis (1977) show that the number of aggressive behavioral reactions increases only for ninety-six hours of the deprivation period and then declines. These authors have assumed that prolonged REM sleep deprivation leads to the exhaustion of the brain catecholamines, as imipramine, which raises the activity of the catecholamine system, improves the learning of active avoidance in some animals even after 120 hours of deprivation.

This point of view fully coincides with the author's theoretical ideas. Indeed, the conditions of REM sleep deprivation according to Jouvet should provoke the reaction of renunciation of search: the frustration of the need for activity, above all search activity when this method is used, combines with the irremovable aversive impacts connected with the fall into the water at the onset of every REM sleep episode. Compensation for this state in REM sleep is impossible due to the REM sleep deprivation. Only during relatively early deprivation stages when the animals are temporarily taken out of this stressful situation to an open field with more favorable conditions does the rebound of frustrated activity, its compensatory increase, which manifests itself in behavioral agitation, appear. The author assumes that the recent series of experiments of Rechtschaffen et al., (1983) can also be explained exactly in these terms.

Compared to the classical REM sleep deprivation procedure according to Jouvet, Rechtschaffen's procedure at first glance permits equating the control and experimental animals by the deprivation conditions and avoiding excessive stress for both groups. The control and the test animals are forced to make efforts to avoid getting into the water an equal number of times a day. But the test animals do so whenever they fall asleep or enter into the REM sleep phase, whereas in the control rats such plunges are not connected with sleep and they have a chance to make up for lost sleep while the experimental animals are awake. Thus, the fundamental difference between the groups is confined to the fact that the experimental group is deprived of all sleep or of certain stages, and this eventually leads to the death of the animals. There is a high direct correlation between the duration of survival and the degree of intactness of REM sleep. Before they died the test animals showed pronounced distress symptoms and a high energy expenditure. The same lethal consequences follow from total sleep deprivation, from selective full REM sleep deprivation, and from a similar deprivation of highamplitude NREM sleep (Everson et al., 1986).

This may give the impression that only sleep deprivation is responsible for all physiological changes and the death of the test animals. However, in the author's opinion, this is not quite so. The author assumes that the deprivation conditions according to Rechtschaffen and according to jouvet have much more in common than it seems at first glance. Indeed, the test animals plunge into the water whenever they need sleep or its certain stages. Thus, the actual requirement for sleep or for certain stages of sleep is frustrated. In the course of such frustration the animal learns the inexorability of punishment. Naturally, each time it can eventually escape the water, but it cannot prevent the very fact of frustration used as punishment. What can be easily coped with in waking is more agonizing when sleep is greatly needed. A control animal does not develop an experience of the inexorability of punishment at every attempt to satisfy its sleep requirement, whereas an experimental animal forms exactly such an experience, eventually leading to learned helplessness. In such a case REM sleep as the compensatory mechanism related to search behavior is suppressed. In the case of selective deprivation of high-amplitude NREM sleep a rivalry is created between the requirement for NREM sleep due to the deprivation itself and the great REM sleep requirement due to the conditions of deprivation (the development of learned helplessness). Such a rivalry shortens the REM sleep in these animals compared to the control group. This makes interesting Rechtschaffen's observation that, even among the control animals in the gravest functional state was the rat that showed the shortest REM sleep. Thus, in the final analysis, the lethal effect of the deprivation of sleep and its individual stages is due to a combination of conditions that provoke the state of renunciation of search and simultaneously impede the use of the REM sleep compensatory mechanism. This conclusion is indirectly supported by the results of the study of postdeprivation restorative sleep. To the authors' own surprise, both after the selective REM sleep deprivation and after the total deprivation of all sleep, the animals showed, above all, a compensatory "rebound" of only the REM sleep. Only the rats administered the selective deprivation of the high-amplitude NREM phase in the restorative sleep exhibited NREM rebound, but in these cases, too, the NREM sleep rebound appears together with an almost equally intensive REM sleep rebound (Everson et al., 1987).

In the author's view, the outlined ideas concerning the function of REM sleep and dreams can help solve many debatable problems of sleep psychophysiology. Among such problems, in particular, is the role of sleep in memory and learning processes.

It has been shown that REM sleep grows longer at certain stages of the solution of emotionally significant complex problems, which the animal or human subject is originally unprepared to handle, called unprepared learning (McGrath and Cohen, 1978). REM sleep deprivation carried out directly after such learning greatly impedes it. The author proposes the following interpretation of these facts: a complex problem that the subject is not ready to solve (Seligman, 1970) may cause a renunciation of search with much greater probability than a simple one, especially at the early stages of the solution when failures prevail over successes. If the state of renunciation of search is not overcome by REM sleep, this state itself will make it impossible to find the right solution or keep it in memory. Therefore, the lengthening of the REM sleep directly before the critical point in the learning, after which the animal fully develops the habit, is not surprising. However, in some cases the lengthening of REM sleep may be found to be not enough to compensate for the state of renunciation of search, especially if the REM sleep is functionally inadequate. In these cases it may increase more in the animals that are the least successful in forming the new habit. On the other hand, not all animals exhibit a reaction of renunciation of search encountering complex problems, and some, on the contrary, may display a reaction of surrender even facing simple problems. Hence, the basic possibility of polymorphism and ambiguity of sleep changes in these conditions.

Short-time sleep deprivation by the Jouvet method, as said earlier, leads to the frustration of search behavior and its rebound after the deprivation is removed. The high level of motor activity and the high excitability of the central nervous system in such cases may not simply further the learning of simple active avoidance, but even may interfere with passive avoidance. This may determine divergences between research findings. REM sleep deprivation following the learning of complex forms of behavior disturbs those compensatory mechanisms of self-regulation that help overcome the state of renunciation of search. This state remains and upsets the processes of information retention. For example, it is known that depression and unproductive anxiety negatively interfere with learning.

Finally, another paradoxical fact is the absence of REM sleep in such a highly developed animal as the dolphin (Mukhametov, 1988). The author sees only one explanation for this phenomenon. In the natural conditions the dolphin maintains constant active interaction with the environment, a state of constant search. This contact with the environment continues unabated throughout twenty-four hours since the dolphin sleeps now with its left, now with its right hemisphere, one of the two remaining constantly awake. Apparently, the state of renunciation of search is not biologically inherent in a dolphin. Hence, the absence of REM sleep in this animal. An indirect confirmation of this hypothesis is the fact that dolphins find it very difficult to adapt themselves to forms of captivity that limit the possibility of active behavior. If they fail to go over to a new behavior type, such as active interaction with the experimenter, these highly intellectual animals soon die.

The proposed conception makes it possible not only to put together the results of vastly different investigations into one system, but also to eliminate a number of contradictions between them.

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