Effects of chlorpromazine and d-amphetamine on observing responses during a fixed-interval schedule

Abstract

Pigeons were trained to peck a response key that briefly produced stimuli correlated with the passage of time in a fixed-interval schedule of food presentation for pecks on another response key. Pecks on the key that produced food were not likely near the end of each fixed interval, whereas pecks on the key that produced the discriminative stimuli were most likely to occur during the middle portion of each fixed interval. Chloropromazine (3.0--30.0 mg/kg) and d-amphetamine (0.03--3.0 mg/kg) produced inverted U-shaped dose-effect curves with response rate on the food-producing key as the dependent variable, and monotonically decreasing functions were obtained for the discriminative-stimulus producing responses. A "rate-dependency" interpretation adequately described the drug effects on the temporal distributions of pecks on the food-producing key, but was not consistent with the disruption of the temporal distribution of pecks on the key that produced the discriminative stimuli. The pecks on the discriminative-stimulus producing key had some of the properties of schedule-induced, or adjunctive, behavior. The effects of amphetamine and chlorpromazine on the rate of adjunctive behaviors may not be predictable from control rates.

The effects of d -amphetamine, chlordiazepoxide, α-flupenthixol and behavioural manipulations on choice of signalled and unsignalled delayed reinforcement in rats

“…Firstly, it should be noted that amphetamine might fail to disrupt behaviour controlled by external stimuli because it potentiates the effects of conditioned reinforcers, rather than because it improves discriminative stimulus control (Laties et al 1981), and there is little evidence to suggest that amphetamine facilitates control by purely discriminative (non-contingent) stimuli (e.g. Moerschbaecher et al 1979) or promotes responding for informative stimuli that are not themselves paired with reward (Branch 1975). Secondly, the fact that amphetamine increased preference for the large reinforcer in the presence of the cue implies that the cue does more than ameliorate an amphetamine-induced deficit.…”

Effects of Chlorpromazine on Fixed‐ratio Responding: Modification by Fixed‐interval Discriminative Stimuli

“…Whereas effects of chlorpromazine on overall rates of FR responding were comparable, effects on FI responding differed between subjects (see also Branch, 1975;Dews, 1958;Leander, 1981a;Leander & McMillan, 1974, for reports of both rate-increasing and ratedecreasing effects of chlorpromazine on Fl responding of pigeons); this provides evidence for increased generality of the effects of chlorpromazine on FR responding described here.…”

Observing responses of chain-schedule stimuli and effects of d-amphetamine and morphine

“…For three-link chain schedules with links of equal duration, only the terminal-link stimulus signals an average reduction in time to food and therefore should maintain the highest rate of observing. Observing for three chain/serial stimuli in previous experiments (e.g., Hendry & Dillow, 1966;Kendall, 1972;Branch, 1975) indicate that observing rates were greater in the middle link relative to the terminal link under response-dependent food schedules. Some authors (e.g., Kendall, 1972) have reasoned that response competition between food-key responding and observing resulted in the decreased rate of observing within the terminal link.…”

“…Fewer studies (e.g., Clark, 1969;Raiff & Dallery, 2006) have examined drug effects (d-amp and nicotine, respectively) and conditioned reinforcement within an observing procedure. In a study most similar to the present experiments, Branch (1975) established observing (1.5-s stimulus duration) under a simple FI 120-s food schedule with pigeons as subjects. A single observing response (FR 1) resulted in the production of stimuli correlated with thirds of the FI (i.e., a stimulus correlated for every 40 s of the FI).…”

“…After a range of dose effects were obtained, effects of a drug outside the stimulant pharmacological class (morphine, 1.0 -5.6 mg/kg) were tested. This was conducted to determine if only the stimulant drug class would result in increases in observing rates (cf., Branch, 1975).…”