Relations of heart rate level to motor activity and food deprivation in the rat.

Abstract

Heart rate, an activity index, and duration of grooming and rearing episodes were measured in rats which lever-pressed under either continuous or variable interval schedules of reinforcement while undergoing increasing levels of food deprivation. The results showed heart rate level did not change with increasing deprivation in lever pressing animals and did not seem to be influenced by activity levels or behaviour patterns such as rearing or grooming. Extinction produced a decrease in heart rate level, though behaviour became more invigorated. Observations of phasic heart rate and activity curves associated with instrumental lever responses are also presented. The data are discussed in relation to studies showing heart rate-deprivation functions and heart rate-movement associations. VANDERWOLF AND VANDERWART (1970) observed that heart rate recorded in rats under conditions of satiation and food deprivation was associatedwith phasic movements or erectness of posture. It was found that heart rate was higher during face washing, licking, and rearing, than during scratching, walking, and resting. Food deprivation up to 47 hours had no effect on heart rate measured during these various specific categories of behaviour. Vanderwolf and Vanderwart (1970) suggest that many of the studies relating heart rate in the rat to learning, motivation, arousal, etc. may be demonstrating only the effects of changes in these specific motor patterns on heart rate. The present experiment attempts to examine this possibility with regard to the heart rate level and hours of deprivation relation described by Belanger and Feldman (1962) and others. Reviews of experiments concerned with heart rate and deprivation can be found in Appley (1970), Belanger (1967), Rlevings (1971), Campbell and Misanin (1969), and Malmo and Belanger (1967.The present study examines activity levels and behaviour patterns (grooming and rearing) for the influences on heart rate suggested by Vanderwolf and Vanderwart (1970). In addition, an attempt is made to assess the role of activity in reinforcement-related phasic heart rate patterns of the type obtained by Ehrlich and Malmo (1967).