Heart rate and muscle tension correlates of conditioned suppression in humans.

ECG T-wave amplitude, muscle tension, and heart rate concomitants of conditioned suppression

“…The study aimed also at investigating another aspect of the findings reported by Di Giusto et al (1974). From the absence of any observed conditioned skeletal muscle response, the authors inferred a lack of generalized muscle tension and concluded that such findings were at variance with the hypothesis that conditioned suppression is mediated by skeletal muscle "freezing" (Lyon, 1968).…”

“…From Figure 1, it is evident that the greatest difference between CS + and CS -occurred on Trial 2. On the basis of these results, it was decided to employ only two classical aversive conditioning trials in the main study rather than the five conditioning trials used by Di Giusto et al (1974) .…”

“…rather than the separate groups control used by Di Giusto et al (1974). The latter type of control is generally considered inadequate (Black, 1971 ;Rescorla, 1967), since it does not allow the accurate separation of generalized excitation and excitation which is specific to the CS.…”

“…The shock electrode was att ached to the dorsal surface of the left forearm with a crepe bandage. As with Di Giusto et al (1974), this site was chosen since it has been shown to reduce the possibility of muscular involvement during shock stimulation (Tursky, Watson, & O'Connell, 1969). A reduction in skin resistance was achieved by shaving the skin and then lightly rubbing the area with pumice stone.…”

“…The results of studies which have recorded electromyographs (EMGs) from several different sites during aversive stimulation suggest that the particular muscle site chosen by Di Giusto et al (1974), viz, the right extensor carpi radialus, may have been inappropriate. For instance, Carroll (1971) observed dominant flexor muscle activity with unpleasant visual stimuli.…”