A procedure for studying the within-session onset of human drug discrimination.

The purpose of the present study was to develop a procedure for measuring the within-session onset of human drug discrimination. During daily sessions, under double-blind conditions, caffeine-abstinent adults ingested a letter-coded capsule containing 178 mg caffeine or placebo. Trials were presented at 30-s intervals, beginning immediately after drug ingestion and continuing for 60 min. On each trial, subjects could guess which of their two letter-coded drugs they had received by pressing a left button (for one drug) or right button (for the other drug); subjects could also press a center "no guess" button instead of guessing. Each trial ended after one button press. After each session, subjects were told which drug they had received. Subjects earned one point (worth $0.10 per point) for each correct guess. Subjects lost either 0, 1, or 10 points for each incorrect guess; the point-loss contingencies were varied in random order across sessions. Discrimination earnings accumulated across all sessions. The point-loss contingencies decreased random responding and delayed the discrimination time course. Overall, this procedure provided an orderly and relatively continuous measure of the within-session onset of drug discrimination and should have a range of applications in understanding the human behavioral pharmacology of drugs.     

Effects of different substance misuse in genital reflexes of paradoxical sleep deprived male rats

As psychostimulants are widely abused, their neurochemical and behavioral effects have been extensively studied for many years. Our previous data demonstrate that paradoxical sleep deprivation (PSD) enhances drug-induced penile erection and ejaculation. PSD in association to drugs of abuse like cocaine potentiated genital reflexes in male rats. In this sense, the present study investigated if three substances abused by young people--such as Delta(9)-tetrahydrocannabinol (Delta(9)THC), alcohol and caffeine--had any significant effect on the genital reflexes in PSD rats. The results indicated that PSD induced erection in 50% of the rats and 20% ejaculated. In addition, there was no significant alteration in the number of animals exhibiting genital reflexes neither on the frequency of these behaviors when challenged with Delta(9)-THC or alcohol or caffeine after 96 h of PSD. These findings show that Delta(9)THC, alcohol and caffeine when administrated isolated did not produce alterations in genital reflexes in the PSD male rats.     

Anger arousal,deindividuation, and aggression

We tested the notion that angered persons' aggression would be increased through a process of excitation transfer when they are deindividuated, but that individuated subjects would be most aggressive in circumstances under which they could use the information that they had ingested an arousing drug as a pretext for their aggression. Sixty-two male undergraduates participated under either deindividuated or individuated conditions, ingested either 350 mg of caffeine or a placebo, were informed that they had either taken a stimulant or a nonarousing drug, and were all angered by a confederate. According to prediction, when deindividuated and aroused by caffeine the amount of noxious stimulation subjects delivered to the provocateur was greater if they believed that the drug they had taken was nonarousing than if they thought it was a stimulant; in contrast, individuated subjects' aggression was greater when aroused subjects believed the drug was a stimulant. The results are discussed in terms of excitation transfer and the effect of aggression inhibition on the use of information about one's arousal.     

Effects of d-amphetamine and caffeine on schedule-controlled and schedule-induced responding.

The effects of d-amphetamine and caffeine were studied on rates and patterns of lever pressing and schedule-induced licking under fixed-interval schedules of food pellet presentation. In addition, the effects of caffeine were studied on lever pressing and licking under a multiple fixed-ratio fixed-interval schedule. Caffeine reduced mean overall rates of licking at lower doses than it reduced mean overall rates of pressing under the fixed-interval schedules, but the effects of caffeine on both licking and lever pressing depended largely on the control rate of responding. d-Amphetamine reduced mean overall rates of lever pressing and licking at about the same dose, but the effects of d-amphetamine also were a function of the control rate of responding.     

I. V. Zavadskii and the beginnings of behavioral pharmacology: an historical note and translation.

I. V. Zavadskii, who worked in Pavlov's laboratory between 1907 and 1909, performed a study that has many of the characteristics of modern behavioral pharmacology. He studied the effects of alcohol, morphine, cocaine and caffeine on the conditioned salivary reflex. A translation of his paper and some brief comments on his life are presented.