ABSTRACT

In Trowill's study, rats rewarded for an increase in Heart Rate (HR) increased only about 6 bpm, while their yoked-controls showed a decrease of -20.4 bpm. Since Trowill's innovative study and the dramatic impact of the more impressive sequelae the phenomenon of autonomic instrumental conditioning has been recognized as an event of major theoretical and practical significance. Most of the studies were carried out with curarized rats as subjects and HR was the response manipulated. In one study curarized animals have a mean HR level of about 460 bpm and an absence of significant conditioned HR responses. The criticisms which have been indicated here, and to whatever extent the reader chooses to generalize them to other studies, are intended to apply only to instrumental HR conditioning studies using curarized rats. The animals used were Sprague-Dawley derived Simonsen albino male rats aff weighing between 400 and 500 gm.