Effects of N-methyl-d-aspartate receptor (NMDAr) uncompetitive antagonists in a delay discounting paradigm using a concurrent-chains procedure.

Impulsive choice is often assessed in rodents using a delay discounting (DD) paradigm in which the delay to a large reinforcer (LR) increases across the session. This procedure allows one to test the effects of pharmacological manipulations within a single session. Because discounting is influenced by sensitivity to reinforcer magnitude (SRM) and sensitivity to delayed reinforcement (SDR), applying quantitative analyses (e.

Ruptured ectopic pregnancy with a negative urine pregnancy test.

Ectopic pregnancy is commonly seen as a differential diagnosis of first-trimester vaginal bleeding. Often the diagnosis is made based on a combination of exam findings, transvaginal ultrasound, and a positive pregnancy test. Our case describes a patient with a history of ectopic pregnancy treated with methotrexate and serial human chorionic gonadotropin measurements that were decreasing appropriately.

Effects of Group I metabotropic glutamate receptor antagonists on sensitivity to reinforcer magnitude and delayed reinforcement in a delay-discounting task in rats: Contribution of delay presentation order.

Metabotropic glutamate receptor 1 (mGluR) blockade has been shown to decrease impulsive choice, as measured in delay discounting. However, several variables are known to influence an animal's discounting, including sensitivity to delayed reinforcement and sensitivity to reinforcer magnitude. The goal of this experiment was to determine the effects of mGluR, as well as mGluR, antagonism on these parameters.

Effects of N-methyl-D-aspartate receptor ligands on sensitivity to reinforcer magnitude and delayed reinforcement in a delay-discounting procedure.

Rationale: The N-methyl-D-aspartate (NMDA) receptor has been recently identified as an important mediator of impulsive choice, as assessed in delay discounting. Although discounting is independently influenced by sensitivity to reinforcer magnitude and delayed reinforcement, few studies have examined how NMDA receptor ligands differentially affect these parameters.

Objectives: The current study examined the effects of various NMDA receptor ligands on sensitivity to reinforcer magnitude and delayed reinforcement in a delay-discounting procedure.

Effects of NMDA receptor antagonists on probability discounting depend on the order of probability presentation.

Risky decision making can be measured using a probability-discounting procedure, in which animals choose between a small, certain reinforcer and a large, uncertain reinforcer. Recent evidence has identified glutamate as a mediator of risky decision making, as blocking the N-methyl-d-aspartate (NMDA) receptor with MK-801 increases preference for a large, uncertain reinforcer. Because the order in which probabilities associated with the large reinforcer can modulate the effects of drugs on choice, the current study determined if NMDA receptor ligands alter probability discounting using ascending and descending schedules.