Title: Heart rate and the behavioral orienting response in the rat
Abstract: The behavioral orienting response (OR) and heart rate (HR) were simultaneously recorded in rats in response to 85-dB auditory stimuli. The behavioral OR habituated with respect to frequency and amplitude, whereas HR responses did not fully habituate in either aspect. Most HR responses were characterized by accelerations (76%) followed by decelerations (23%). However, no differential cardiac responding with or without the behavioral OR was observed. In addition, there was no unequivocal relationship between somatic and cardiovascular responses. It is suggested that HR changes are concomitant responses rather than specific components of orienting, and that their relationship to orienting does not follow simple notions of inhibition and facilitation.