(see tig. 2) which is known to be the key recipient of nerve signals 

 mediating the sensation of pain. We should not be surprised that a 

 sentinel for pain plays a role in attention, because pain is always a 

 possible outcome of the self-paced probing through which the sys- 

 tem learns about the world. Returning to the muscle-directing region 

 itself, as well as to Ivry's above-mentioned remark about anticipa- 

 tion. Jane Pedersen. Peter Johannsen. Christen Bak. Bent Kofoed. 

 Knud Saermark and Albert Gjedde ( 1998) have shown that this part 

 of the brain has to be activated when a human subject is expecting 

 sensory input. This work added the important factor of cortical lo- 

 calisation to the earlier work of Hans Kornhuber and Liider Deecke 

 (1964). who monitored event related potentials from the scalps of 

 subjects, and found significant features in their experimental traces 

 about 800 milliseconds before actual movement. This "readiness 

 potential" as they called it is a sort of advanced neuronal notice of 

 impending action. One could use the term bootstrapping to describe 

 the manner in which the components of the closed loop autono- 

 mously control attention, without dualistic intervention by any mys- 

 tical external agency. 



Consciousness and Emotion 



But why should things be arranged in just this fashion? How do 

 the underlying anatomy and physiology conspire to produced the 

 desired result? A somewhat indirect clue was provided by the work 

 of Benjamin Libet. Elwood Wright Jr. Bertram Feinstein and Dennis 

 Pearl (1979). They studied perception by patients awake during 

 brain surgery (having obtained the patients" permission to do so, 

 and exploiting the fact that the brain itself comprises no pain sen- 

 sors). A brief tap on the back of one of the hands sends a signal to 

 the appropriate part of the somatosensory cortex (part of the sensory 

 cortex indicated in fig. 2) on the opposite side of the brain, the 

 signal reaching that point after about 40 milliseconds. The awake 

 patient naturally feels such a tap. and correctly locates it to the back 

 of the hand. If the surface of the corresponding part of the exposed 

 cortex is electrically stimulated, the patient again experiences a tin- 

 gling on the back of the appropriate hand. However, Libet and his 



13 



