Russell C. Leaf

SIMPLE METHOD FOR CER CONDITIONING AND MEASUREMENT

The effect of Pavlovian fear CSs on water drinking by thirsty rats was studied after fear conditioning with several procedures. Forward conditioning produced typical CER suppression of drinkometer-recorded licking, but backward conditioning and other Pavlovian control procedures did not. Effective CER suppression was demonstrated after 4 conditioning trials with a 1-trial test procedure. This is apparently the most simple and rapid technique available for evaluating CER suppression of ongoing responding.

Initiation of mouse killing in non-killer rats by repeated pilocarpine treatment

Abstract Some, but not all, laboratory rats spontaneously attack and kill mice. Repeated daily intraperitoneal administration of pilocarpine initiated mouse killing by all non-killer rats. Thus, all rats possess brain mechanisms that control predatory attack and killing of mice.

Chlordiazepoxide and diazepam induced mouse killing by rats

Chlordiazepoxide HCl, at dose levels from 2.5 mg/kg to 80 mg/kg, significantly increased the low base rates of mouse killing (3–9%) observed in large samples (N=100/ dose) of Holtzman strain albino male rats. Maximal killing rates were obtained at doses from 7.5 mg/kg to 20 mg/kg. Diazepam was equally effective, and several times more potent than chlordiazepoxide. Pentobarbital did not increase killing. Killing induced by chlordiazepoxide was blocked by d-amphetamine SO4, but not by l-amphetamine, at dose levels similar to those that block undrugged killing in this strain (ED50=1.5 mg/kg). Unlike pilocarpine-induced killing, the effects of chlordiazepoxide were not increased or decreased significantly by either peripherally or centrally active anticholinergic drugs, over wide dose ranges of these agents; nor were the effects of chlordiazepoxide increased by repeated daily administration.

Effects of scopolamine on operant avoidance acquisition and retention

SummaryThree experiments demonstraced that i.p. doses of 0.1 mg/kg scopolamine resulted in higher response rates and lower shock rates than normal during acquisition of lever pressing Sidman avoidance responses by rats. A fourth experiment confirmed previous reports that well-trained rats were not affected by such low doses of the drug. The scopolamine-induced acquisition performance changes were a function of baseline shock rate. Maintained savings of the higher response rates, but not of the lower shock rates, were, nevertheless, found in subsequent undrugged sessions after initial acquisition with scopolamine.

Effects of stimulus color, pattern, and practice on sex differences in mental rotations task performance.

Redundant color information improved performance for both sexes on the Shepard Mental Rotations Task (MRT; Shepard & Metzler, 1971). Absolute score gains for women were larger than those for men; therefore, relative improvement was greater. Substantial practice effects, also favoring women, were apparent in both studies. Study 1 showed that redundant color improved performance by 0.25 SD. Study 2 demonstrated that redundant black-and-white pattern information did not have any effect; a second visuospatial channel, redundant color, was a critical factor in improving scores of men and women on difficult mental rotations tasks.

Inhibitory effects of pre- and posttest drugs on mouse-killing by rats

Mouse-killing in rats was gradually inhibited by repeated posttest injections of d-amphetamine (1.5 mg/kg), l-amphetamine (1.5 mg/kg) or pilocarpine (7.5 mg/kg), but not by control substances. Of these drugs, only d-amphetamine inhibited killing when given prior to a mouse-killing test. Further experiments suggested that anorexia per se did not contribute to drug-induced inhibitory effects, but that changes in internal state were important to the development of inhibition. Pretest injections appear to inhibit predatory killing by a direct pharmacological action on some target site or sites, while posttest injections produce a learned aversion to predatory killing.

Human classical aversion conditioning: Nausea versus electric shock in the reduction of target beverage consumption

Abstract Two experiments were conducted to investigate the effectiveness of the nausea-pro-ducing Pseudo-Coriolis Effect (PCE) in conditioning aversions to beverage consumption. The first experiment assessed the effectiveness of this procedure while controlling for demand characteristics. The second experiment compared this procedure with electrical aversion conditioning. This study demonstrates the effectiveness and relative superiority of the PCE in classical aversion conditioning. Consideration is given to the parameters and potential applications of this procedure

Effects of Shock Intensity, Deprivation, and Morphine in a Simple Approach-Avoidance Conflict Situation

The effects of water deprivation, shock level, and morphine on punishment-induced suppression of water drinking during a single conflict acquisition session were studied. Suppression of drinkometer-recorded licking was greatest with high levels of intermittent foot-shock for drinking, and suppression was reduced by morphine. Level of deprivation had no significant effect.

Effects of cholinergic drugs on prey-killing by rodents

Abstract Pilocarpine induced some rats to kill mice. As tolerance or habituation to repeated doses occurred, increasing numbers killed mice and other prey. Methyl atropine, which selectively blocks peripheral actions of pilocarpine, increased killing induced by pilocarpine. Scopolamine, which blocks its central as well as peripheral actions, blocked induction of killing by pilocarpine. Mixed central cholinergic facilitative and peripheral cholinergic inhibitory actions on killing could explain these results. Other cholinergic agents, however, including nicotine, oxotremorine, arecoline, eserine, neostigmine, and methacholine were ineffective over a broad range of doses. Pilocarpine did not induce killing in guinea pigs and hamsters. If a central cholinergic system for selective control of killing exists in rodents, it is not easily activated.

Recovery Time as a Measure of Degree of Conditioned Suppression

The time period of complete cessation of drinking, after drinking is suppressed by presentation of a previously conditioned fear-eliciting CS, provides a one-trial test of CER magnitude. Suppression time is much longer after conditioning with a 10-sec. CS-US interval than after conditioning with longer CS-US intervals (N = 66).