Jeanne M. Stahl

Discrimination of gamma-hydroxybutyrate and ethanol administered separately and as a mixture in rats.

The physiological effects of gamma-hydroxybutyrate (GHB) are complex and not yet clearly defined. GHB has been labeled as a recreational drug and is reported to be frequently coabused with ethanol (ETH). Other studies have yielded discrepant results as to the interaction between GHB and ETH. Thus, the present study investigated extensively the discriminative stimulus of GHB and ETH and a mixture of the two compounds. Thirty male Long-Evans rats were divided into three groups and trained to discriminate doses of either 300 mg/kg GHB, 1000 mg/kg ETH, or a mixture (MIX: 150 mg/kg GHB+500 mg/kg ETH) from vehicle on a two-lever fixed-ratio (FR) 10 schedule of food reinforcement. Dose-response curves were attained in each group with its respective training drugs. GHB and ETH did not cross-generalize in the ETH- and GHB-trained rats, respectively. However, when the effects of the MIX were tested in the GHB- and ETH-trained rats, a greater than additive response was observed. Testing also revealed that the MIX-trained rats did not perceive a novel stimulus but a near-equal contribution from GHB and ETH. This study provides evidence of a complex relationship between GHB and ETH and opposes previous work reporting cross-generalization between GHB and ETH.

Food competition and social experience effects on V1a receptor binding in the forebrain of male Long-Evans hooded rats.

The present study investigated the effect of social status in Long-Evans hooded rats established during food competition on V(1a) vasopressin receptor (V(1a)R) binding in the lateral septum (LS), medial preoptic area (MPOA), bed nucleus of the stria terminalis (BNST), anterior hypothalamus (AH), and central/basolateral amygdala (CeB). Serum concentration of testosterone (T) and corticosterone (CORT) was also measured. In Experiment 1, thirty-two lever-trained weight-matched rat pairs were placed in operant chambers where a single bar press provided access to milk reinforcement. A dominant-subordinate relationship, determined by the duration of drinking, was evident in 88% of the pairs. Sixteen rats were lever-trained but did not interact and served as no-treatment (NT) controls. In the LS, V(1a)R binding in the subordinate (SUB) group was significantly higher than in the dominant (DOM) group. V(1a)R binding was significantly higher in the LS, BNST, CeB, and AH in the NT group than in the other groups. The levels of CORT and T were not affected significantly by group membership. Experiment 2 investigated whether the binding effect in the LS was related to differences in fluid consumption. The results did not indicate a significant effect of fluid consumption. In the rat, V(1a)R binding in several forebrain areas seems to be affected by brief periods of social interactions, and, in the LS, it also appears to be related to dominance status.

Modifying law enforcement training simulators for use in basic research

Several approaches to using simulation as a method for teaching good judgment in the use of firearms by law enforcement officers and military personnel were investigated for their potential applications to research: the GAMMA Live Fire Video Training System, the FireArms Training Systems Simulator (FATS), and the Judgment Under Stress Training (JUST) simulator. Each instrument uses real-time, computer-controlled, life-sized projected video images of scenarios that may or may not present a threat, and handguns that fire real or simulated ammunition. The subjects respond to a sequence of “shoot/no-shoot” judgment scenarios resulting in data on judgment, reaction time, and accuracy. The JUST simulator was found to be more easily modifiable in capturing data on performance at microanalytic levels. Although true interactive simulations are not feasible with this system, this was not seen as a hindrance to its usefulness for research.

DESIGN AND USE OF A U.S. CENSUS DATA COMPUTER LABORATORY FOR TEACHING UNDERGRADUATE RESEARCH METHODS

This paper discusses the design and development of an interdisciplinary social science computer laboratory for teaching undergraduate research methods courses and research components of applied and theoretical courses. The U.S. Census of the Population, a database commonly used in all of the social sciences, is used in order to give students research experience and to avoid ethical problems involved in working with animal and human subjects in an undergraduate course. Some issues in laboratory design and required changes in teaching methods are discussed.

Performance of rats on the Maier three-table task following septal lesions occurring 24 hours after birth.

The purpose of this study was to determine whether behavioral sparing would be demonstrated when septal lesions occurred prior to the age at which the tested behavior first appears in normal rats. Rats given septal lesions at 1 day or 7 days after birth performed at approximately chance on the Maier three-table task when tested at 90 days of age. Rats that had control electrode insertions at the same ages performed at a level similar to normal animals. Animals given septal lesions at either age explored significantly more than did control animals. Results are discussed in terms of the constancy over time of the septal contribution to performance on the three-table task and the involvement of the septum and hippocampus in the processing of spatial information.

State-dependent performance of rats on a complex maze task

State-dependent learning occurs when information acquired in one chemical state fails to transfer or only partially transfers to another state. Thirty-five Long-Evans rats learned to run the Hampton Court maze and then were tested in an ABA design, alternating between administration of one of three doses of morphine sulfate (6, 10, or 15 mg/kg) and saline. At the two highest drug doses, regardless of direction of switch (saline to morphine or vice versa), the subjects’ running time increased significantly after the first switch, but not at all or to a much lesser degree after the second switch, indicating possible state-dependency effects. Analysis of errors indicated that, after the first state change only, rats that had switched from morphine to saline committed errors immediately after the change under all three dose conditions, but those that switched from saline to morphine continued to run the maze without error. The results of this study indicate that morphine-related state changes can create temporary disruptions in performance—independently of direct drug effects—on a task with a long learning curve such as this one.

AN AUTO-ADJUSTING SHAPING PROCEDURE

A variable interval (VI) schedule is described that automatically adjusts the programmed rates of reinforcement in accordance with the rates of responding of subjects during the two immediately preceding 30-sec time intervals. The schedule prescribes that as rate of responding decreases, programmed reinforcement rate increases, and that when rate of responding increases, reinforcement rate decreases. Thus, programmed reinforcement rate is adjusted continuously until some target value is reached. Ten rats were exposed to this procedure five times a day at 1-h intervals. The target, set at VI 120 sec, was reached by most subjects within 4 days of training. Subsequently, all subjects responded consistently during five daily 1-h sessions with VI 120 sec. This procedure speeds up the training of subjects on long VI schedules and substantially reduces the time and effort spent observing the subjects and adjusting the schedule parameter value during the early development of responding.

Use of a computer-controlled firearms training simulator in perception response time experiments

This paper describes the use of a custom-configured computer-controlled firearms training simulator to measure perception response (reaction) time (RT) to a stimulus in which the degree of threat presented is a manipulable variable across trials. The computer records the number of frames of videotape traversed between the point of presentation of the threat in the video stimulus and the point at which the subject responds by drawing the firearm. For the purposes of data analysis, these frame-count measures are converted to RT measurements. Example data are presented that capture perception RT at both thedraw-stimulus and thefire-stimulus points in situations for which either only one threat or more than one threat exists. Other elements, such as degree of threat and accuracy of response, provide additional data.