movement (REM) sleep, beeause the eyes have been diseovered to 

 move about erratically during this phase. It was previously believed 

 that the eyes were serving a dreaming counterpart of wakeful vision 

 during such episodes. But perhaps the real explanation is more 

 down-to-earth. The point is that all the other skeletal muscles are 

 immobilized during REM sleep, presumably because the schemata- 

 consolidation mechanism referred to above might otherwise cause 

 the limbs to move (something which does in fact occur in certain 

 pathological conditions). But with the eyelids closed, the eyeballs 

 would be free to move without causing any sensory input. But there 

 is more to this story, because the muscle-immobilized REM period 

 is limited to a few minutes, in order to ensure adequate blood cir- 

 culation (the recent cases of deep vein thrombosis during long air 

 journeys serving to illustrate that point). But the corneas of the eyes 

 also contain blood vessels, and the rapid movements of the eyes 

 against their lids might be nothing more sophisticated that a periodic 

 bout of massage! 



Returning to the idea of schemata consolidation during dreaming, 

 this concept recently received endorsement by Robert Stickgold's 

 group (Mednick et al., 2002), who demonstrated that short bouts of 

 sleep can prevent perceptual deterioration. Commenting on this fas- 

 cinating finding, Pierre Maquet, Philippe Peigneux, Steven Laureys 

 and Carlyle Smith (2002) wryly noted that it is a good idea to 

 occasionally be caught napping! Amir Mazur, Edward Pace-Schott 

 and J. Allan Hobson (2002) have recently made observations which 

 suggest that the differences between the self-awareness typical of 

 waking and its diminution during dreaming may be due to biochem- 

 ical deactivation of the prefrontal cortex in REM sleep. 



Intelligence and Creativity 



One attractive consequence of the theory of consciousness I have 

 been sketching is that it leads to what I feel is a believable account 

 of intelligence. It views this as simply the ability to link together 

 elementary muscular movements — actual or merely simulated dur- 

 ing thought — into more complex movement patterns. If that is a 

 reliable picture of intelligence, it would suggest that children who 



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