experiments concerned with the influence of the vagal and sympathetic innervations of the heart and of peripheral reflex mechanisms are reported on the deceleration of heart rate observed on test trials during classical conditioning in human Ss. An increase in vagal restraint was observed to be the basis of the deceleratory response, which in turn masks the manifestation of sympathetic acceleratory effects. The latter were only observed when the vagus was pharmacologically blocked and when a very intense UCS was used. When the conditioned pressor responses were blocked pharmacologically, as evaluated by direct recordings of arterial blood pressure, the deceleratory response was not changed, indicating that the peripheral homeostatic reflex mechanisms are not the basis for this response and that it is likely a conditioned response.

No abstract

The anticipatory human heart-rate responses resulting from the use of three classes of unconditioned stimuli were evaluated. These stimulus classes were derived from a proposal that high stimulus intake results in a deceleratory heart-rate UCR, that rejection of environmental intake results in an acceleratory cardiac UCR, and that physical exercise results in cardiac acceleration. It was expected that the typical conditioning process would produce CRs comparable in direction of the UCRs. With the respiratory pattern controlled, the cardiac changes to each stimulus class were essentially as expected. However, the anticipatory response was deceleratory in each case. It appears that the cardiac change in anticipation of stimulation of any type is deceleratory and the result of an atypical conditioning process.

No abstract

This experiment was intended to evaluate further an hypothesis in which perceptual and sensory-motor performances were considered to be influenced by autonomic processes via autonomic regulation of cortical activity. For this purpose, lability and level measures of sudomotor activity and heart rate were obtained during rest and performance in 54 male Ss. The hypothesis was consistently supported in 7 significant or near-significant correlations out of a possible 14. Faster performance time on the sensory-motor task was found with Ss having low resting heart rate, increased heart-rate variability during performance, and low levels of skin resistance. Faster performance time on the perceptual task was found in Ss with a high frequency of GSR activity during performance. Also, an interaction effect was suggested between some of the autonomic measures, being most pronounced in the perceptual task.