Based on LinkC's comment (thanks) I went looking for what I could find in this area & did locate these documents (also Wikipaedia has some interesting entries)...
document #1 ...
http://necsi.edu/projects/yaneer/sleep/ ... issoc.html
An extract ...
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During sleep the brain is active but is largely isolated from sensory neurons. It is here proposed that during sleep the mind further subdivides into isolated neuron groups. This division decomposes imprinted experience from the waking period into pieces which then form the building blocks for analyzing and responding to future circumstance. The approach is based on the perspective that the central purpose of the brain is not to remember experiences, but rather to obtain from them knowledge that will serve in future circumstances.
Modern theories of sleep suggest it serves a biological restorative function, or that sleep exists because of a survival advantage in removing primitive man from danger., However, the existence of dreams has motivated theories in which sleep plays an important role in psychology or how the brain processes information., One modern framework for describing information processing by the brain is the neural network. In this framework, Crick and Mitchinson , suggest that dreams cause selective forgetting of undesirable or parasitic neural network states. In contrast Geszti and Pázmándi suggest dreams are a form of relearning. In these works, roles in information processing are attributed to Rapid Eye Movement (REM) sleep, or dream sleep. The other parts of sleep, where dreams are infrequent (non-REM sleep), are still generally believed to have a biological role. However, total sleep deprivation causes psycho-functional, not physiological, deterioration in humans and the primary effects occur with loss of non-REM sleep.2
In this article it is proposed that both REM and non-REM sleep play a significant role in information processing by the brain. It is suggested that during sleep brain subdivisions are temporarily isolated from each other. The known specificity of neurotransmitters makes it possible selectively to 'turn-off' synapses or axons that connect between subdivisions. Such selective control enables isolation of the brain from sensory input even though sleep is a neurologically active state. The possible role of further internal dissociation of the brain appears to be discussed here for the first time.
It is proposed that the temporary subdivision of the brain during sleep, and a selective relearning process during this time, enables and maintains the distinct roles of different subdivisions of the brain during waking. The fundamental motivation for subdivision of the brain is the need to generalize experiences by isolating aspects that may reoccur in other contexts. Quite literally the act of combining aspects of prior experience is directly the result of recombining states of partially independent brain subdivisions.
It is further suggested that dissociation in sleep performs an essential restorative function. Neural networks fail catastrophically when overloaded. Selective relearning also results in a selective forgetting of information that prevents overload failure. Experimental observation of psycho-functional failure after sleep deprivation,2 which prevents this restorative function, may be directly related to overload failure.
Consequences of this discussion are far reaching both for public policy and progress in understanding brain function and disorders. Public attitudes, and corporate behavior, motivated by or motivating scientific thought often proceeds on the assumption that sleep is a waste of time. In contrast, these proposals suggest that well-balanced sleep schedules are of central importance in human functioning not only for the short term effects of sleep deprivation but for its long term effects. Moreover, the temporary subdivision of the brain and selective relearning may provide a step towards understanding mechanisms of pattern recognition, the 'logic' of human language and the ability of separate parts of the brain to function coherently. Finally, it provides predictions that can be tested by the new techniques currently available for mapping regional brain activity.
This article is arranged as follows. First, the conventional neural model of adaptive learning is reviewed. The existence of brain subdivision is motivated within the neural model. The problem of neural network overload and the impact of selective relearning is discussed. The role of temporary dissociation and the purpose of different levels of sleep are described. The impact of sleep deprivation and other malfunctions of the sleep process are presented. Finally, it is suggested that the role of sleep provides an intrinsic basis for human individuality.
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document #2 ...
http://www.sciencedirect.com/science?_o ... 98be9d27b2
An extract ...
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Main Text
The last decade has seen a dramatic increase in our understanding of sleep-dependent memory consolidation, moving the concept of a role for sleep in memory consolidation from a generally discredited (or at best ignored) idea to a largely accepted tenet among both memory and sleep researchers. While the number of players in this field remains small, it is growing rapidly, and researchers are now approaching the topic with a remarkably broad array of tools (Table 1). These range from strictly behavioral studies in humans — demonstrating, for example, selective memory enhancement across a night of sleep [1] — to studies of the role of sleep in modifying experience-dependent cortical plasticity in the cat visual cortex [2]. Claire Jackson and colleagues have now reported in Current Biology [3] that imprinting in domestic chicks is dependent on post-training sleep; their work further shows how the contribution of individual neurons to the memory of the imprinting stimulus develops over the 24 hours following imprinting.
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