tempt at movement then becomes the focus of attention, and of 

 eonsciousness, if the creature possesses that faculty. 



The requirement that the system is able to make predictions, and 

 detect any mismatch, makes reasonably heavy demands of the un- 

 derlying brain circuitry, not the least with respect to feedback loops. 

 One could say that these are acting in parallel with the external loops 

 that close through the surroundings — the ones that run from the 

 animal's muscular movements, through the surroundings, and back 

 into the system via the relevant sensory receptors. For example, my 

 voice produces sound waves detectable by my ears. The internal 

 loops can support the passage of nerve signals even in the absence 

 of overt muscular movement, and when that happens, the animal 

 merely thinks. Thinking is thus internal simulation of our muscle- 

 mediated interactions with our surroundings. Whence our ability to 

 imagine hearing ourselves speak. 



We ought to pause at this point and consider attention in more 

 detail. In creatures not possessing consciousness, priority amongst 

 simultaneous sensory inputs is apportioned automatically, and it is 

 hard-wired into the nervous system. So the sensory input exercising 

 the strongest control on the reflexes, at any instant, is preordained. 

 The plots of such creatures' lives could be said to be written in their 

 genes. Their systems may be impressively sophisticated neverthe- 

 less. For example, a creature's movements will produce a great 

 amount of sensory feedback that could be called routine, as when 

 it touches its own body. It has to learn to ignore the nerve signals 

 produced in that manner, and Christopher Miall, Donald Weir, Dan- 

 iel Wolpert and John Stein (1993) have suggested that the cerebel- 

 lum (indicated by dentate nucleus, Hemispheres, interpositus nu- 

 cleus, and Pars Intermedia in fig. 2) might mediate incorporation 

 of these oft-repeated movement-and-feedback correlations into the 

 creature's standard behavioral repertoire. Indeed, Richard Ivry 



planning region (FEF is the frontal eye field, which does the same job for the eyes). 

 The author believes that the return routes (feedback loops) via which signals are fed 

 from that region back to the sensory cortex are vital to consciousness. (A key to the 

 other abbreviations is given in Cotterill, 2001b.) 



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