Studies of instrumental behavior with sexual reinforcement in male rats (Rattus norvegicus): I. Control by brief visual stimuli paired with a receptive female.

Abstract

We describe a novel procedure for measuring instrumental sexual behavior in the male rat by using a second-order schedule of presentation of sexual reinforcement, an estrous female. Experimental assessment and validation of the paradigm have been achieved by examining fa) the importance of the conditioned stimulus in maintaining instrumental responding by measuring the effects of its omission during a test session, (b) the effects and motivational specificity on instrumental behavior of the postejaculatory refractory period (a period of sexual unarousability) and of satiety for food by measuring the impact of each manipulation on animals working for food and for a female, (c) the effects of replacing an estrous female with an anestrous one as the earned reward, and (d) the correlations between conditioned and unconditioned measures of sexual behavior. We conclude that the second-order paradigm provides a means of distinguishing between the etfects of neuroendocrine manipulations on incentive motivational and performance variables underlying the expression of sexual behavior.Attempts to understand the neuroendocrine mechanisms regulating sexual behavior have generally relied on a behavioral analysis that involves, almost exclusively, the quantification of consummatory responses. These include sexual reflexes, such as intromission in males and lordosis in females, as well as species-specific patterns of investigation, mounting, and proceptivity (Beach, 1976;Sachs & Barfield, 1976). Relatively little is known of the psychological processes affected by manipulation of the various neural and endocrine mechanisms that control the expression of sexual behavior. At least part of the explanation lies in the fact that sexual motivation has proved to be a difficult concept both to define and to measure, despite many attempts over several decades to specify factors affecting it (see Beach, 1956;Grossman, 1967: Pfaff, 1982Toates, 1986).Clearly, sexual behavior is not easily accommodated by homeostatic models of motivation: There are no obvious deficits that energize it, and operational definitions that depend on, for example, deprivation states are practically worthless. In terms of incentive motivational theories (see Bindra, 1976;Konorski, 1967;Morgan, 1979), which emphasize the processing of information related to stimuli, it has also proved difficult to define the processes affected by sex steroids, which critically determine the expression of sexual behavior and

Effects of medial prefrontal or anterior cingulate cortex lesions on responding for cocaine under fixed-ratio and second-order schedules of reinforcement in rats

“…Omission of the drug-associated light stimulus resulted in disruption of response rates and patterns in control rats, with a significant decrease in Ic values. These findings confirm previous studies that have demonstrated the ability of reinforcer-associated cues to maintain rates and patterns of responding under secondorder schedules using cocaine, heroin or food as reinforcers in monkeys and pigeons (Goldberg and Tang 1977;Kelleher and Goldberg 1977;Cohen et al 1979;Goldberg et al 1979;Cohen 1991) and sexual contact as a reinforcer in rats (Everitt et al 1987). The present study also showed changes in response patterns in the absence of changes in response rates, indicating that simple rates of responding may not be sufficient as an indicator of stimulus control over behaviour under the conditions tested here.…”

Acquisition, maintenance and reinstatement of intravenous cocaine self-administration under a second-order schedule of reinforcement in rats: effects of conditioned cues and continuous access to cocaine

“…The following measures for each interval were routinely taken during the experiments described below: (a) the number of responses on the active lever during each fixed interval, (b) the time to complete the first FR10 response unit, which represents a measure of the latency to initiate responding, and (c) the index of curvature, which provides a quantitative measure of the overall pattern of responding during each interval and the degree of schedule control over responding (Fry et al 1960;Everitt et al 1987). All experimental data were subject to ANOVA (CLR ANOVA, Clear Lake Research, USA) for Apple Macintosh computers.…”

Conditioned Reinforcement: Experimental and Theoretical Issues

“…For example, the primary reinforcer may disrupt the behavior because it is physically debilitating, as is the case with large dosages of some drugs (e.g., Katz, 1979). An interesting example of such usage has been reported by Everitt, Fray, Kostarczyk, Taylor, and Stacy (1987) in their investigation of the reinforcing properties ofaccess to a receptive female rat for lever pressing by a male rat. Noting that the delivery of the primary reinforcer substantially disrupted lever pressing for substantial periods after its occurrence (because ofthe inherent difficulties ofdelivering small portions of the reward) and that previous attempts to condition operant behavior using sexual access as a reward had generally failed to maintain significant amounts of behavior, they presented their female rat contingent on bar pressing on an FH 15-min schedule, with presentations of the female at the end of the interval paired with a 30-s signal.…”