August 1, 2003
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Neuroendocrinology Letters incl. Psychoneuroimmunology & Chronobiology

NEUROENDOCRINOLOGY LETTERS
including Psychoneuroimmunology, Neuro
psychopharmacology,
Reproductive Medicine, Chronobiology
and Human Ethology
ISSN 0172–780X

PRESS RELEASE
1-Aug-2003

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Latest from the Office of the Editor-in-Chief

 

Preview next coming issue: Vol.24 Nos. 3/4,
Release date:
August 27, 2003
ORDER and DISORDER in the brain
(Olga Quadens)


Order and disorder in the brain

The function of the brain was developed for the survival of the human species on this planet. We do not know how the brain has emerged nor how it functioned when it commanded the actions of our remote ancestors. We may at most guess a mutation that favored the emergence of Homo sapiens somewhere in the line of the great apes. With the last mutation, the probability of speech appeared but we do not know, more recently, when men created the first signs of what was to become language. In this Homo sapiens, the EEG and other physiological endpoints such as the eye movements and the activity of the muscles evidence the states of consciousness.

The brain is one of the most complex systems encountered in nature. It is made of billions of cells endowed with individual electrical activity and interconnected in highly intricate networks. The average electrical activity of a portion of this network forms the electroencephalogram (EEG). The interest in studying it as a function of the development of intelligence has been spurred by the need to understand how the brain responds to environmental information.

Decades ago, this problem was first met as a natural history, with the description of the sleep patterns in mentally handicapped children in whom some repetitive patterns, such as the spindle waves in the EEG and the rapid eye movements of REM sleep appeared to be particularly altered when compared to normal children. Today the early descriptions have been confirmed with more sophisticated means. It appeared that the repetitivity or redundancy is a brain mechanism that may serve for adjustment to changes in the environment.


The traditional method of eye balling the EEG does not allow to detect particular types of oscillations among its many wave forms but other more recent methods deriving from the analysis of chaotic systems, namely the dimension of its strange attractors, allow to detect immediate changes in the EEG dynamics. Attention was paid to two physiological endpoints, the waking EEG and the patterns of the eye movements during sleep, for they are reflecting underlying brain mechanisms associated with learning. Sleep has fascinated the scientific community for several decennia. It was popularized by its pioneers, William Dement in the U.S.A. and by Michel Jouvet in France. As from 1962, a small European team studied the dynamics of the eye movements of REM sleep. It showed that, when learning is impaired, the eye movements are decreased in number during REM sleep and their distribution is mainly random.

Memory is an important parameter in the learning process and it appears that, in the mentally handicapped, the two kinds of memory, the long and the short term one, are altered. Their networks are widely distributed in the brain and are involved in the production of the EEG spindles. Therefore their distribution is also altered in the mentally handicapped. The two types of sleep signals, the eye movements of REM sleep and the EEG spindles, belong to similar logical functions. No wonder that they are associated with learning in a different but complementary way and that their alterations are correlated with mental retardation. In these patients, the appearance, out of chaos, of the order that is needed for intelligence and memory to function, is altered.

This alteration is present as from birth in Down' syndrome babies who will be retarded. If, during the baby's sleep, the distribution of the eye movements of REM sleep remains random, intelligence will not develop. The same is true when the signals appear in long sequences of uninterrupted bursts of eye movements or waves as in epilepsy. Interestingly enough, studies of sleep of pregnant women have shown that the patterns change as a function of term and that, as from the 7th month of pregnancy they evidence similarities with the eye movement patterns of sleep in the premature baby of a similar gestational age as if her brain was in resonance with the brain of her fetus. The nature of the information transmitted between the pregnant woman and her baby is unknown. It is believed that this information is genetic, that it is the memory of the species that passes from the mother to her fetus, in the way of a code. One cannot rule out a link between the brain function of the pregnant woman and a cell memory of which the elements, like antigens, cross the placental barrier and cause cell links to become established in the fetus.

Already before birth, brain waves appear in the fetus. Their pattern will change with maturation We have no way of knowing the sensory content of the baby's brain but it would be presumptuous to assume that there is none. Sometimes in adults, the physiological endpoints of sleep are dissociated and their recombinations resemble those found in newborns. These states are associated with vivid hallucinations. They look like intrusions into wakefulness of the states of sleep and dreaming. Their sleep characteristics resemble those of premature and newborn babies. The question arises whether there is a similarity between the sensory world of the baby and the hallucinations of subjects whose sleep parameters are dissociated. Are the hallucinations associated with narcolepsy and cataplexy a physiological memory, that of an epoch of one's life where the perceptions of time and space are still absent, of a primary universe that will eventually lead to the intellectual and critical universe of the waking adult? One may wonder whether a brain function, which is still devoid of time structures, cannot but be associated with images, which are likewise devoid of time references. It may lay the ground for human imagination, evolving into legends and thought.

When establishing a relation between some sleep patterns and learning, one has to look into a periodic activity during wakefulness, which may be equivalent to REM sleep. A candidate for this equivalence is attention. When the organism is solicited by stimulation, it turns towards the source of it. The physiological basis of attention is associated with a specific brain activity bound to wakefulness and occurring periodically during the day. It is obvious in the cat. When its attention is aroused by a bird or a mouse, it will remain motionless for some time before attacking its prey. In a laboratory situation, which limits his movements, it will turn the head and the eyes towards the source of the stimulation. Attention is to wakefulness what REM sleep is to sleep. In the cat, attention is linked with a program that drives him to hunt birds and mice in order to survive. In human it is the drive to hominisation that drives him to pay attention to others in order, first, to explore his physical and cultural environment, then the whole of reality.

The ratio between order and disorder in the signs of REM-sleep increases in men and in women alike, from birth until 50 years after which age it is stabilized. In women, periodical changes occur in this ratio every two weeks, at the turning points of the hormonal cycles. In the course of the increasing order with age, there may be jumps in opposite direction, from a more to a less organized state suggesting an error in the information. Periods, in which the activity of the brain is temporarily disorganized only to be reorganized again, run through life. The rate of alternation is higher in the infant and becomes lower with age. They are determined by laws, which we still ignore. One could imagine that epochs of reversed entropy of the brain functions are connected with what we call 'time'.

The last facts evidencing the learning function of the brain concern the results of brain recordings of astronauts working and sleeping in space. The sleep recordings made during the spacelab 1 flight in 1983 disclosed a pattern in the eye movements of sleep that clearly differs between the first and the second night in-flight, and clearly evidenced a similar pattern across the first two nights post-flight. These challenging results led the author to complement them with further experiments on the EEG in weightlessness, during wakefulness, such as they occur during short periods of microgravity. They were performed on board research aircraft flying parabolic trajectories. Results obtained by using the strange attractor dimension imply for the neural processes involved in learning that the normal healthy central nervous system can preserve intact, from input to output, over a period of several days, all the information it receives.

The quantum approach can also be used as a medium between the information and the way of describing it. It is usual at the atomic and subatomic level of matter. At the level of the EEG, this theory can be applied to the sleep spindles only. However it makes coherent the learning function theory of sleep where the sequential association of spindle sleep and REM sleep supports the idea of memory carrying particles of spindle waves allowing the eye movements of REM sleep to code more fundamental elements such as the insertion of recent events at short term in a vast array of emotional strategies.

 

Abstract online: Expected date August 20, 2003

Issue is released in August 2003
Vol. 24 Nos. 3/4, 2003
Neuroendocrinology Letters www.nel.edu

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