42. This statement is incorrect, inasmuch as electro-oscillograms during both states in humans are not so similar as to confound an observer and in rats we have found that theta waves that occur in both attentive wakefulness and in desynchronized sleep are largely different. 18. 20. The Jungian approach believed they are meaningful and contain; information-processing. Jouvet M. Le sommeil paradoxal est-il responsable d'une programmation gntique du cerveau? The gamma-alpha loop has been shown to play no role in producing the movements that characterize dreaming. Vertes & Eastman (2000), for instance, believe that the stressful conditions in experiments intended to demonstrate a role of desynchronized sleep and dreaming in consolidation of memory spoil the results (88). cognitive development. 5. Petersohn D, Schoch S, Brinkmann DR, Thiel G. The human synapsin II gene promoter. Both frequency and voltage of theta waves in rats generally increase during oniric activity, as depicted in figure 7, and in figure 8 a clearcut episode of visual oniric activity is expressed as a potent increase in theta waves frequency and voltage, concomitantly with a burst of eye movements. In 1867, Michelson, a physiologist who was a relative to Kohlschtter, replicated his study and obtained the curve shown in figure 1 (4,8). WebIn a nutshell, the theory states that the biological function of dreaming is to stimulate threatening events in order to rehearse the perception of threats and how to go about Fenn WO, Hursh JB. Instead, they thought that dreams were not provoked by spirits, ghosts or gods, which took over the mind to express themselves through dreaming. The data reported in table 1 reflect a close distribution of the dream content as related to their sensory content. Arch Gen Psychiat 1966;14:238-48. 82. Front Neurol. 128. Accordingly, they are known as PGO (pontine, occipital cortex and lateral geniculate nucleus) potentials. Visual dreams provoke eye movements. 64. The atonia of myoclonia of active (REM) sleep. 80. 43. Desynchronized sleep has been identified in many mammals and birds (16) but below the birds only in crocodiles brief periods of an equivalent phase (eye movements, low voltage electro-oscillograms and cervical hypotonia) seem to occur (17). Selective deactivation of the dorsolateral prefrontal cortex has been found in desynchronized sleep. If the animal is trying to identify the source of an odor that is located at a large distance, snout movements are expected to span wide angles at low frequencies, whereas when the source is near such movements are expected to span narrow angles, at high frequencies, just as during wakefulness. Cravo SLD, Lopes OU, Fraga CAB, Timo-Iaria C. Cardiovascular adjustments to noxious stimulation in decerebrate cats. The reinterpretation of dreams: an evolutionary hypothesis of the function of dreaming. 84. To what degree, and in what way, implications can be drawn from these findings for the psychology of dreaming is controversial. Around 80 per cent of such motor activity was found to occur during desynchronized sleep, what points to its participation in dreaming activity. Fortunately, this author did not suggest that dreaming, with all its movements, is intended to produce heat from the fake muscular contractions that occur as an expression of dreams. Even in humans, such electrophysiological, motor and vegetative signs of oniric activity are enough to know that a dream is going on. 47. Am J Physiol 1937;118:8-14. Expt Neurol 1976;53:328-38. The authors concluded that the correlation they found was probably involved in memory consolidation but such coincidence may indicate that during dreaming memorized information is being revoked to integrate a given dreaming pattern. The first oscillation lasts around two hours, when sleep attains its deepest level; the ensuing cycles last less and their depth tends to decrease until arousal finally occurs, a sequence that recent research has fully confirmed. Dream recall and eye movement during sleep and their relation to eye movements, bodily motility and dreaming. In rats we found similar potentials in the amygdala as related to olfactory dreams, expressed as rostrum movements (32). 50. 35. These interneurons inhibit motoneurons by means of glycinergic synapses (glycine is a powerful inhibitory neurotransmitter), as shown by Soja et al. Santos LM, Valle AC, Sameshima K, Silva MTP, Timo-Iaria C. A linear relationship between theta waves frequency and the speed of learning in rats. Sleep 1999;22:409-18. NeuroReport 1995;6:532-6. Brain 1997;120:1173-97. C R Soc Biol (Paris) 1938;128:533-9. 52. Timo-Iaria C, yamashita R, Hoshino K, Sousa-Melo A. Magoun HW, Rhines R. An inhibitory mechanism in the bulbar reticular formation. In other words, they're simply a byproduct of brain processes during sleep. (eds.) Nofzinger EA, Mintun MA, Wiseman MB, Kupfer DJ, Moore Ry. Fratelli Bocca Editori, Torino 1899. The hypothesis has been recently put forward by Revonsuo (2000) that the function of dreaming is to simulate threatening events, and to rehearse threat perception and threat avoidance (111). In some mammals only one hemisphere at a time may be in desynchronized sleep. It seems that not only humans but also dogs, cows, sheep and goats and the entire family of four-legged viviparous animals do dream. Some presently available explanations seem science fiction, rather than true science. 4. San Diego, 1973. (eds. Behav Brain Sci 2000;23:877-901. In cats, Guazzi, Baccelli & Zanchetti (1966) demonstrated that due to such a cardiovascular hypoactivity the sensory afferents from glomus carotideus and glomus aorticus, that carry information from chemoreceptors sensitive to a decrease in oxygen blood concentration, attain an overwhelming relevance, inasmuch as following the transection of such afferents blood pressure goes continuously down during desynchronized sleep, leading to death (63). The subjects of dreams are broad-ranging and complex, incorporating self-image, fears, insecurities, strengths, grandiose ideas, sexual orientation, desire, jealousy and love". This neural activity is then interpreted by the brain as an internal activity. 70. 22. Further studies have shown that the pathways from the alphacoeruleus nuclei to inhibit the motoneurons are rather complex. Above the transection, synchronized and desynchronized sleep keep occurring but without eye movements. Van de Castle RL. Eye movements in humans predominate because vision is our main sensory channel and our visual memory is overwhelmingly predominant, resulting in preponderance of visual dreams. Deprivation of desynchronized sleep during early development not only retards brain maturation but also inhibits the growth response to the brain environmental stimulation later in life (113). activation-synthesis. 2011 Dec;20(4):998-1008. doi: 10.1016/j.concog.2010.10.005. In humans it has been shown that not only EEG desynchronization but also increase in vegetative functions, such as heart rate and ventilation (27), accompany mental activity. In 1937, Fenn & Bursh, recording the eye movements while their subjects closed and opened the eyes, found that the voltage (V) of the potentials that expressed the movements were proportional to the angle of rotation [V=k.2.sen] in which V is the voltage of the recorded potentials, k is a factor of proportionality and is the angle of rotation (28). In 1926, for example, Denisova & Figurin (9), recording heart and respiratory rate of sleeping children, found that both changed cyclically, what is presently known to occur as vegetative components of dreaming activity. During this bright period of the Middle Ages some physicians also reasoned about dreams. Milbrandt J. This may well reflect auditory dreams, as has been found in humans (36,37). Soja PJ, Lopez-Rodriguez F, Morales FR, Chase MH. Nature, 2002, submitted. Does early night REM dream content reliably reflect presleep state of mind? Shiromani PJ, Lai yy, Siegel JM. Theta waves, discovered by Jung and Kornmller in 1938 (72), were extensively studied by Green & Arduini (73), who proved they are related to arousal. In: Baust, W. 49. Reactivation of hippocampal ensemble memories during sleep. The physiological-functioning theory suggests that dreaming works the same way. Cole AJ, Saffen DW, Baraban JM, Worley PF. Rados R, Cartwright RD. Kohyama J, Shimomira M, Iwakawa y. Brainstem control of phasic mucsle activity during REM sleep: a review and hypothesis. There are many hypotheses to account for the existence of dreams but it is still a matter of debate why and what for we dream. Gottesmann C. Theta rhythm: the brain stem involvement. Interestingly, bilateral ablation of the frontal lobes in cats leads to deep changes of the PGO potentials in the VI cranial nerves and in the mobilization of the lateral rectus muscles during desynchronized sleep (71). With Darwin (1965), we are fully convinced that "at least birds and mammals do dream" (6). By recording potentials from large ensembles of rat hippocampal neurons related to the body position in space (place cells) during behavioral tasks, Wilson & McNaughton (87) found that neurons that fired together when the animals occupied particular locations in the environment (hence the name place cells) also exhibited an increased tendency to fire together during subsequent sleep, in comparison to sleep episodes preceding the behavioral tasks. In cats, tympanic muscles sometimes contract during desynchronized sleep (38), as shown in Figure 4. A correlation has been proposed between the development of desynchronized sleep in children and their waking cognitive maturation (24). 73. Hobson JA. MeSH Considering dreams as hallucinations, Hernndez-Pen (1966) theorized that they are possible because the system responsible for wakefulness is inactivated during sleep, releasing memory tracings which are brought to consciousness. 2. With developments in understanding of the neurophysiology of REM sleep, new From the spinal cord Marini (1997) recorded slow (delta) regularly oscillating waves during desynchronized sleep (81), which may be related to activation of spinal neurons during dreaming. Later, the Roman writer Lucretius, the first popularizer of science, in his book De Rerum Natura (1978) credited these Greek philosophers for the discovery of the characteristics of sleep and dreams (2). Animal experimentation, by making it possible to implant electrodes in any part of the nervous system and to lesion and stimulate (electrically or chemically) also any nucleus or pathway, has been of the utmost relevance for the understanding of the mechanisms causing not only sleep but also the manifestations of dreaming. Brain activity during this time keeps us (36,37) have recorded contraction of the tympanic muscles (stapedius and tensor tympani) during human sleep. Analysis of psychological theories concerning functions of dreams. The earliest theory to emerge, Freuds psychoanalytic theory, takes an observational approach to identifying the function that dreams serve. Freud theorized that dreams are the result of unfulfilled wishes or desires in the subjects life. At the end of the 19th century several authors published on oniric activity. Proc Assoc Res Nerv Ment Dis. WebWhen a person entered rapid eye movement (REM) sleep, it activates circuits within the brain stem. Consequently, Foulkes concludes that they do not dream but this conclusion is probably incorrect, inasmuch as at this age children have a highly limited narrating capacity and their poor reports about dreams are certainly linked to such a limitation, not their absence. In this review, the neural circuits underlying dreaming and the physiological functions associated with it are summarized. Esoteric power, useless, useful: considerations about dreams in cognitive-behavioural therapy. It is well known that during desynchronized sleep the pupil undergoes an increase in diameter (midriasis), which is not produced by direct sympathetic activation but rather to parasympathetic inactivation, that overcomes the tonic pupillary constrictor activity of the parasympathetic system during synchronized sleep. In cats desynchronized sleep appears also as tonic cortical desynchronization (figure 3) but in the hippocampus, septal area and amygdala theta waves predominate, as in rats and rabbits. 24. In an extensive review on this subject, Solms (2000) describes a complete cessation of dreaming in patients with posterior cortical or deep bilateral frontal lesions (96). However, human oniric behaviors are also expressed as lips, tongue and facial movements, as well as fingers, toes and whole limbs jerks, as described above. Vision is our predominant sensory channel, so much so that if we hear a sound we immediately convey the eyes to the source of the sound, trying to identify its origin, even if vision is absent. 125. Ergebn. Metabolism during desynchronized sleep tends, in fact, to be equal to or even larger than that of waking (131,132). 117. 3. However, we still do not know why most motor units are inactivated while a few ones are mobilized, causing real but incoherent and non-efficient movements. They may be involved only in intermediate steps of the processes that cause such movements. Some of his statements, hereby reproduced in a simplified form from his book on sleep and dreams, briefly illustrate his contribution to the study of this subject: "All creatures that have four limbs and are sanguine (mammals) display signs that they dream while asleep. Foulkes D. Children's dreams. Electroencephal Clin Neurophysiol 1990;76:388-99. Several authors also quantified the kinds of dreams as related to their sensory content. Brain Res 2002, submitted. The most prominent, the activation-synthesis hypothesis, derived its view of dreaming directly from the neurophysiology of REM sleep, in particular the role of the brain stem, and in its original form regarded dreams as not essentially meaningful. However, we all know that many dreams are not emotional at all. We suppose, instead, inasmuch as dreams are forgotten if we are not aroused while dreaming or within ten to fifteen minutes immediately after the dream has ceased, that it may well be that dreams are forgotten because the reticular activating system is highly deactivated during desynchronized sleep and thus the memory of the dreams cannot be consolidated (110). As any information consciously identified, a dream triggers a specific behavior, that we call an oniric behavior. Hence, experiments with such animals are extremely valuable and thus will be emphasized in the present review. Fortunately, thanks to this peculiar incomplete motoneuron inhibition we are able to record movements occurring in both humans and non-human animals and thus infer the presence of dreams. Where do dreams come from? They also argue that even "expensive and cumbersome evoked potential and computer averaging approaches have not helped us to analyze and compare desynchronized sleep physiology with that of waking in an effective way". In non-human animals the report regarding dreams is obviously impossible but, fortunately, a dream can be detected in both humans and other species by analyzing its motor, vegetative and electrophysiological manifestations, as will be described below. Of dreaming table 1 reflect a close distribution of the dorsolateral prefrontal cortex has been shown to play role... 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