CENTRAL CONTROL OF RECEPTORS AND SENSORY TRANSMISSION SYSTEMS 



751 



STIMULATION 

 POINT "A" 



'^/'^^''»'''■'%^^*^ 



RETICULAR 

 RESPONSE 

 POSTERIOR 



TO ANTERIOR 



RETICULAR 

 RESPONSE TO 

 CORTICAL 

 STIMULATION 



MULATtON 

 POINT "B" 



SHOCK 

 INTERVALS 



4 MS 



12 



20 



25 



31 



39 



48 



59 



93 



rv/'^flv^Nw^ 



D^V 



*\Nv^ 



\|L/Vv,sM****M 



»/|^,.^S,.VSv^ 



' /V,^^>^''**^ 



'1 J-^^-mA^N^ 





^^^M-^-H^^*^ 



^^/^v^***'*N 



*^v^ 



COMBINED 

 CORTICAL 



a 



RETICULAR 

 STIMULATION 



SHOCK 



INTLRvaLS 



4 MS 



[yx/'^s^ 



p/w^*^ 



p^/^-^^-^,- 



/y/irv^ 



fW^.^^^S.^PV-^Mi* 



20 



25 



31 



39 



48 



59 



93 



FIG. 10. Coiticifugal inHuences 

 upon a conduction pathway in 

 the brain-stem reticular forma- 

 tion. Responses recorded from 

 bipolar electrodes in the anterior 

 brain stem show effects of single 

 cortical shocks on volleys ascend- 

 ing from a test stimulation site 

 in the posterior brain stem. Left 

 column: Effects of cortical shocks 

 applied to point 'A' on the 

 medial surface of the monkey 

 hemisphere. Right column: Effects 

 on the same pathway of shocks 

 applied to a more anterior 

 cortical site, point 'B". Note that 

 ascending brain-stem volley is 

 facilitated when cortical shock is 

 delivered to point 'A' 31 msec. 

 prior to posterior brain stem test 

 shock, whereas facilitation from 

 point 'B' occurs at 9 and again 

 at 48 msec, at which moments 

 the brain-stem pathway is being 

 inhibited from point 'A'. This 

 illustrates the principle that a 

 number of cortical sites can exert 

 a controlling influence on ascend- 

 ing systems intrinsic to the brain 

 stem, thereby being able, pre- 

 sumably, to interfere with mecha- 

 nisms involved in sensation. 

 [From Adey el at. (i).] 



