Opposing heart rate reactions associated with behavioral states of excitation and inhibition.
Following the development of an excitatory bradycardia conditioned response (CR) to a CS+ paired with a shock US on Day 1, three groups of rats were given one of three inhibitory training procedures on Day 2 with a different CS (CS-). Then on Day 3 the inhibitory capacity of each CS- was examined on a modified combined cue test in which CS- was given slightly before CS+ and on a reversal conditioning test in which CS- was now paired with the US. The three inhibitory procedures consisted of CS- alone (CSA) trials, explicitly unpaired (EUP) CS- and US trials, and truly random (TR) CS- and US trials. During inhibitory training, the bradycardia CR to CS+ was replaced with a tachycardia reaction to CS- in the EUP group but not in the other groups. Subsequent to inhibitory training the EUP group and to some extent also the TR group showed a decrement in the excitatory bradycardia response to CS+ when compared to the robust HR slowdowns displayed by the CSA group. It was suggested, within the context of opponent process theory, that the separate USs given the EUP and TR groups (especially the former) during inhibitory training may have led to conditioning of inhibitory tendencies to CS- and that these in turn generalized and decremented previous established bradycardia responding to CS+ and the development of a new bradycardia to CS- during reversal conditioning.
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003214:Conditioning, Classical / Q000502:physiology*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D051381:Rats