546 HANDBOOK OF PHYSIOLOGY >^ CIRCULATION I 



A. CONTROL B. EXERCISE 



PAPER 

 SPEED 



50 MM /SEC 



C. STIMULATION (CHLORALOSE ANESTHESIA) D. IMPLANTED 



ELECTRODE 



3 DAYS LATER 

 NO ANESTHESIA 



Heart Rate 



STAND >!l EXERCISE 



RECLINE ] 



iam; POU 



Bipolar electrode Unipolar electrode 



0.25 MM /SEC 



: uWi'*=« v.-^ ~^^ 



Left Ventricular Diameter 



r 



mJ'^f^y..fmif^f!^ 



■5^*f*ir" 



140 

 I8O' 



120 



60 



MM 

 52- 



48 



MM 



HQ Left Ventricular Pressure 



8o:n n "^''^'^""'^ 



MM 

 H6 ^ 



20- 



RECLINE S TIMULATE 

 STAND 



STIMULATE 



■~i-C3V, 



STIMULATE 



Jii^^f 



,'^M^^j 







9»il^m,0i}<ftm^ 



v_ 



■4ip 



Diastolic Pressure 



dP/dT 





>■ T.lW' 



•*.*» 



Ipmmm 



FIG. 8. Stimulation of small discrete areas in the region of the H2 fields of Forel causes changes in 

 ventricular performance which are similar in many respects to those observed during spontaneous 

 exercise, both under chloralose anesthesia and after recovery from the anesthesia. (From Rushmer 

 & Smith. I'liyswl. Rev. 39: 4!, 1959.) 



as well as cardiovascular adjustments. However, the 

 cardiac response is completely independent of the 

 respiratory and motor activities since it can be elicited 

 without decrement after administration of svnciu-inc 



to dogs under artificial respiration (57). Furthermore, 

 certain sites of stimulation produce the same cardio- 

 vascular responses without motor activity. 



The sites in the diencephalon that produce a left 



