Instrumental Learning of Systolic Blood Pressure Responses by Curarized Rats: Dissociation of Cardiac and Vascular Changes

Rats with skeletal muscles paralyzed by curare to rule out the effect of muscular activity were given artificial respiration and were rewarded by escape and/or avoidance of mild electric shock for either increasing or decreasing their systolic blood pressure. A chronic catheter was implanted within the abdominal aorta for measurement of same. Each trial was signaled by the onset of a light and tone; each experimental rat was yoked to a control rat. The yoked control received exactly the same treatment as the experimental S, except that it could do nothing to avoid being shocked, and was shocked whenever the experimental S was shocked. Over-all group increases and decreases of 22.3% and 19.2%, respectively, were obtained for the experimental groups, and were significantly different from the changes in the control groups. All experimental Ss without exception changed their blood pressure in the rewarded direction. Analyses of heart rate and temperature did not reveal any significant changes either between experimental groups at the beginning, at the end of training, or within experimental groups during training. Implications for learning theory, psychosomatic pathology, and treatment are discussed.