mystery of yawning
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
http://www.baillement.com
resolutionmini

mise à jour du
17 octobre 2011
Psychol Forsch. 1970;33(2):165-88.
Irrelevant behaviour, information processing
and arousal homeostasis
Juan D. Delius
 
Department of Psychology, University of Durham, Durham, England
and Department of Neurosciences, Univrsity of California, - San Diego, U.S.A.

Chat-logomini

 
Displacement activities and arousal Juan D. Delius
 
Yawning : a displacement activity ?
Le bâillement: une activité substitutive ?
 
Self-injurious and stereotypic behavior
 
Summary. This paper expands a new hypothesis on the causal mechanisms underlying irrelevant behaviour. It begins with a critical summary of earlier theories which attempted to explain displacement activities, but failed to predict the consistency with which certain types of behaviour are shown in stressful situations by s variety of species. Behavioural and physiological studies suggest that these behaviour patterns are closely associated with the incipient activation of sleep. The functional significance of this link and some of the causal processes which may be responsible for it are discussed. Paradoxically, however, displacement activities occur when animals are in a state of high arousal. The concept of arousal is reconsidered in the light of information theory and assumed to be closely correlated with the information processing rate in the nervous system. The relationships between neural and autonomic arousal are considered in this context. It is argued that over-arousal may occur when information handling exceeds the limited channel capacity of the system, with a consequent loss of efficiency. It is pointed out that there are mechanisms capable of controlling the information influx into the brain, and it is hypothesized that they are tied up in a feedback mechanism which regulates arousal and which involves the activation of a de-arousal system, correspdnding to the neurological sleep mechanism. Displacement activities are viewed as cànsequences of this regulatory activation of the sleep system. This hypothesis is then cornpared with existing theories of displacement and its relationship with them is discussed.
 
 
 
This evidence indicates that in a number of species the behaviour patterns shown as displacement activities, particularly grooming, are also normally associated with inactivity, drowsiness and sleep; indeed, the latter is often itself a displacement response. Whether this can be generalized to other species and to other displacement behaviours remains uncertain, because relevant information is usually lacking as, for example, in the case of the fanning of the stickleback (Sevenster; 1961). The idea that individual behaviour responses are facilitated by specific levels of arousal or degrees of wakefulness is not new, and there is empirical evidence to support it (Bindra, 1959a).
 
The origin of this association is fairly obvious. Much of the animal's behaviour can be assumed to have high priority, in the sense that it cannot be postponed without impairing the animal's or its progeny's surviva!: feeding, fighting, courtship etc. These activities typically require high degree of responsiveness to environmental stimuli, with precise timing and orientation, and often a marked level of motor activity. In brief, animals performing this type of behaviour can be said to be in a state of enhanced wakefulness or arousal.
 
Other activities, such as grooming and sleeping, are not so dependent on precise timing for functional effectiveness; they have low priority and, can be postponed until the high priority activities have been carried out, without markedly impairing survival. Such behaviour is often characterized by an absence of precise patterning dependent on external stimulation; many appear to be centrally "preprogrammed" motor coordinations that only require triggering and involve restricted motor activity. Hence they can be carried out in states of diminished wakefulness. It is therefore reasonable to assume that an organizational pattern which causally linked these activities has been selected for in evolution.
 
There is uncertainty regarding the causal processes underlying this association. Although there is some contradiction in the relevant studies, it may be that the secondary, long-latency component of the cutaneously evoked potentials at central levels, which seem to be related to the occurrence of specific, more complex types of behavioural responding, here grooming, is of a larger amplitude during drowsiness and the early stage of sleep than during wakefulness or deep sleep. Whether other mechanisms, such as activation of the grooming motor coordination centres by the sleep system play a role, must remain an open issue for the time being.
 
A complementary mechanism may also contribute to the link between sleep and grooming. Roitbak (1960) and Pompeiano (1965) have found that in the cat repetitive stimulation of cutaneous afferent, is an extremely effective procedure for generating-sleep. Such type of stimulation does, of course, arise during grooming and it is conceivable that if grooming is triggered perhaps by external stimulation, it could through this mechanism tend to be followed by sleep. The implication that the performance of certain types of activities is conducive to the induction of sleep or at least relaxation is not a new idea; in man, for exampIe the performance of a repetitive behaviour pattern (Oswald, 1962), lying down (postural facilitation, Lind, 1959) or closing the eyes (cut-off, Chance, 1962) is claimed to have such an effect. Here then, the activation of grooming and perhaps some other behaviour patterns would be the primary response, and sleep or drowsiness the secondary effect following it.
 
The nature of the connection of some of the other behaviour patterns with sleep is less obvious, particularly the staring down and pecking of birds. Possibly it follows an efferent suppression of the peripheral visual fields by the sleep system. This then enhances behaviour controlled by foveal vision (so called tunnel vision), which in turn diverts the gaze away from stimulating surroundings.
 
 
Arousal Reinterpreted
 
The De-arousal Hypothesis
 
At this point it is possible to return to displacement activities. As we have seen, the situations in which displacement activities occur: conflict, frustration, thwarting and novelty, are associated with signs of arousal in the conventional sense; in other words, the animals show signs of enhanced responsiveness, marked activity and electroencephalographic as well as autonomie signs of increased arousal. Paradoxically, however, we have also seen that some of the behaviour patterns shown in displacement are associated, by various criteria, with the incipient activation of sleep. In the context of the foregoing this contrast is highly suggestive of a regulatory process, where the activation of sleep system counteracts an increase in arousal.
 
The displacement situations can be assumed to provide the animal with more information and to demand from it more information proeing than other situations. In conflict, it is exposed to two contradictory assemblies of information, between which it has to choose. In the frustration and thwarting situation, an established sequence of behaviour leads to failure, and presumably the animal engages in finding alternative solutions, a process which must require intense information sampling and processing. In the case of exposure to novel stimuli, the increased information influx is obvious. More precise data on this point are needed, but as yet are difficult to come by, because estimates of information processing rates presume a reasonably good knowledge of the processing modes used by the nervous system. Accepting that the displacement situations involve relatively high rates of information hanriling, it seems likely that they could often entail an overloading of the chaannel capacity with a consequent deleterious effect on the organisms efficiency. To counteract overloading in such situations I suggest that reduction in the processing rate is achieved by a concomitant activation of an arousal inhibiting mechanism, the sleep system, which has the property of reducing the overall information influx into the animal. Displacement activities are the epiphenomenal consequence of this feedback activation of sleep.
 
It is not possible to specify with any certainty at this stage the detailed neural organization of this regulating mechanism. I suggest that the level of arousal (i. e. the information processing rate) is monitored ither via a polysensory system, like the reticular formation, or through detection of an electrical concomitant of a high level of processing, such as potential changes, or perhaps by measuring the level of some metabolic consequential correlate of arousal. When the measure exceeds a certain level in relation to the channel capacity, it leads to the activation of the sleep system or a related deactivating mechanism.
 
There is empirical evidence that strong activation of the reticular form tion leads to a rebound activation of the sleep system which then inhibits the reticular formation (Dell, Hugelin and Bonvallet, 1961 Parmeggiani, 1968). Whether this is a purely neural process or, whetl possible sleep hormones (Monnier, Koller and Hoesli, 1965; Pappenhieinaer Miller and Goodrich, 1967) play a role, cannot be decided.
 
The activation of the sleep system, either directly or through th inhibition of the reticular activating system, affects the afference sensory information through the centrifugal control mechanisms of se sory pathways (Koella, 1966). I contend that this leads to a reduction, of the attention span, that is to an overall reduction of the information inflow and hence of the information processing rate (i. e. arousal), through efferent inhibition of the primary, i. e. visual and auditory, sensory systems. Consequently there is a relative facilitation of the secondary, i.e. cutaneous and perhaps olfactory, systems and behaviour mediatsd by them, as indicated earlier. Other responses may be activated more directly by the dearousal system at motor coordination levels, and some of the activities so induced may in turn be conducive to a reduction of arousal either by cutting down sensory input or by generating repetitive stimulation, facilitating the induction of sleep and thereby reinforcing the original process (Mason, 1967).
 
It is not clear why displacement activities do not always include the complete gamut of sleep-related behaviours (Ewer, 1967 b). Two factors may be responsible: one is the magnitude and time course of sleep activation involved, which clearly will affect the range of behaviours showN. A high dose of barbiturates gives the animal only the chance of showing one or two grooming movements before falling asleep, while a low dose elicits a highly complex and variable sequence of behaviour. Another possibffity arises from the fact that the sleep system cannot be viewed as a unitary center but rather as complex network with more or less differentiated subdivisions, as demonstrated, for example, by the existence of separate though related mechanisms for slow and fast sleep (Jouvet, 1967). Which of these subdivisions are involved in displacement, and how their activation affects the behaviour of the waking animal, must remain open.
 
Any of this behaviour may of course be further modified by incidental adequate external and internal stimulation. For example, displacement grooming might be facifitated by suitable cutaneous stimulation or a pre-existing partial activation of the sleep system, while displacement pecking would increase with hunger and the presence of grains. A consequence of this is that a clear-cut distinction between normal and dislacement occurrences of given behaviour patterns is not possible, in eement with most observational data; this may have to do with the oulty of formulating a precise definition of displacement.
 
Although it is proposed that displacement activities are the reflection a de-arousal process, they do occur in a context of high arousal, one may expect that some of the behaviours shown in these situations are more direct consequences of the heightened arousal. Wood- Gush Guiton (1967), for example, found that chickens would often react th frantic escape attempts to a thwarting procedure which regularly yielded displacement grooming and sleep. Similar escape behaviour reliably be obtained upon electrical stimulation of the reticular activating system in gulls (Delius, in prep.), apparently as a direct effect of high arousal. Pigeons show similar escape behaviour in novelty situations, and EEG recordings support the view that this reflects a state of extreme arousal (own observations). Similarly, if the animal is informationally challenged when it is operating below its maximum channel capacity, may be assumed that the system's first response will be to increase its attention span. Some of the alerting or orienting patterns seen in stress situations may therefore reflect this process (Berlyne, 1967). As we have argued, there are reasons for assuming an overall correlation between central and autonomic arousal and so we may expect that displacement situation will also give rise to autonomic responses. Schmidt 1950) provides good examples of this in dogs exposed to frustrative ttiations, with panting, salivation, defaecation and urination occurring long with displacement grooming and sleep. Similar behaviour appears to be recorded in the open field test for emotionality in rats and mice van Toiler, pers. com.).
 
Finally one would expect the proposed homeostatic process to fail occasions, resulting in over-arousal to the extent that the organism comes behaviourally ineffective. This is reflected in the so-called freez state many animals fail into when facing extreme stressful situations -d which may often be clearly unadaptive, as when stoats simply grab zing rabbits (own obervations) or lions kill apparently paralyzed - debeests or zebras (H. Kruuk, pers. corn.). Even so, many, species seem have managed to evolve an adaptive response out of this freezing beviour: concealment freezing, death feigning, and so on (Hmnde, 1960).
 
Comparing the de-arousal hypothesis with other theories of displacelent, its main virtue is that it explains the specificity and consistency of the behaviour shown in displacement situations and moreover, it provides a logical basis for their relatedness to sleep. It is consistent th the fact that displacement occurs in contexts of high arousal and that the level of arousal modulates irrelevant be haviour (Fentress, 1968). It is concordant with the disinhibition hypothesis (van Lersel and Bol, 1953), in admitting that peripheral stimulation can play a role in determining the displacement behaviour, but has no, difficulty in explaining its occurrence in frustration and thwarting situations. It also accepts that shifts of attention (McFarland, 1966a) are] involved in bringing about displacement activities. The functions of dis: placement activities in the context of the de-arousal hypothesis are consistent with those suggested by Tinbergen (1952) and Chance (1962)i avoidance of disruption of neural processes through a reduction arousal.
 
When assessing the value of the various-theories, consideration must be given to the possibility that the displacement phenomena are hetero-geneous. It may be, for example, that the disinhibition hypothesis is satisfactory explanation of the displacement fanning of sticklebacks, but that the de-arousal hypothesis gives a more adequate account of the causal processes underlying dis placement grooming in gulls. The fact that grooming is the dominan displacement pattern in a wide range of species from insects to man, how: ever, suggests that at least this type of displacement should be ex plainable in terms of a single universal hypothesis.
 
To close, an alternative line of explanation, perhaps related to th de-arousal hypothesis, should be mentioned. As indicated earlier, the sit t, in which displacement activities occur can be characterized stressful. Adrenocorticotrophic hormone injected into the brain ventricles of cats elicits yawning and stretching behaviour (Gessa, Pisano, Vargi Crabai and Ferrari, 1967). These responses are sometimes seen in conjunction with the more common displacement activities of the cat. A secretion is known to follow the induction of psychological stress an takes place in the adenohypophysis, but probably also at some unidentified ventricular secretory organ (Frankel, Graber and Nalbandov, 1967 Among the target organs of ACTH is the hippocampus (aus der Mühle and Ockenfels, 1968), which is involved in deactivation as mention earlier and seems in turn to control ACTH secretion (Mason, Nauth Brady, Robinson and Sacher, 1961/62). Possibly, displacement acitivities are just one component of the general adaptation syndrome (Selye,1959 the organism's response to stress.