Heart rate conditioning in the rat

Classical conditioning procedures were used to evaluate the development and extinction of conditioned HR changes in the albino rat.

The data suggest that the experimental group (a) developed a generalized HR response to the apparatus, their HR remaining consistently (and on Day 4 of conditioning, significantly) above that of the control group during the 2 hr pre-conditioning period; (b) showed an anticipatory HR increase during the CS presentation which was maximum after 4 to 6 sec of CS and was then followed by increases of less magnitude until just prior to and during the UCS period (on non reinforced trials); (c) demonstrated a localized conditioned HR response immediately post-UCS (on non reinforced trials) which appeared to reflect most adequately conditioned HR changes; (d) showed signs of retention of conditioned HR responses on Day 5 and 30 of extinction.     

Analysis of the electrocardiograms obtained from 1000 young healthy aviators

During the course of some investigation¹ on a group of Civil Air Line pilots, the electrocardiographic findings proved to be of more than passing interest because of the relatively large number of deviations from the values generally regarded as being normal. Because of their relatively frequent occurrence in the records from apparently healthy persons, it was not easy to believe that all of these deviations declared some underlying cardiac abnormality. The opportunity to extend this study came a year later when electrocardiograms were obtained from a large number of young aviators at the Naval Air Station, Pensacola, Florida. Although the primary purpose of this study is to add to our knowledge of the range of the normal electrocardiogram, some attention is also given to an appraisal of the usefulness of electrocardiography in aviation medicine.