Both response effort and current intensity affect self-stimulation train duration thresholds.
Self-stimulation thresholds obtained from rate/intensity functions have often been used to measure brain stimulation reward (BSR) under the assumption that these indices are not contaminated by performance factors. However, very few studies have explicitly examined the effect of performance variables on thresholds. The present experiment examined the joint effects of response effort and current intensity on train duration thresholds. Three levels of stimulation current and lever weightings were factorially combined and train duration thresholds (defined as 50% of maximum response rates) were determined for each condition. It was discovered that changes in both current intensity and response effort produced shifts in thresholds, and that these shifts were of approximately equal magnitude. It was concluded that caution must be exercised when interpreting self-stimulation threshold data since, at least under some conditions, both reward (i.e., train duration) and performance (i.e., effort) manipulations produced similar shifts in self-stimulation response functions.
D000818:Animals; D003216:Conditioning, Operant / Q000502:physiology; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012201:Reward; D012653:Self Stimulation / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology