The effects of psychotomimetic and putative cognitive-enhancing drugs on the performance of a n-back working memory task in rats.

Rationale: Working memory impairment is a core symptom of schizophrenia, but no existing treatment remediates this deficit. Inconsistent conceptualizations and few reliable translational measures are major hindrances to understanding the neurobiology of this aspect of cognition. Using comparable task designs may help bridge clinical and preclinical research efforts.

The effects of anorexic drugs on free-fed rats responding under a second-order FI15-min (FR10:S) schedule for high incentive foods.

Many similarities exist between the overconsumption of food, which results in obesity, and drug addiction. The present study investigated the effects of anorectic drugs on responding maintained by high incentive, but nutritionally unnecessary, food reinforcers using an FI15(fixed-ratio 10:S) schedule of reinforcement, similar to that used in studies on the incentive properties of drugs of abuse. Rats were trained to respond on a lever to gain access to two high incentive foods--chocolate chip cookies and cheese.

A comparison of the effects of psychotomimetics and anxiolytics on punished and unpunished responding maintained by fixed interval schedules of food reinforcement in the rat.

Characterization of anxiolytic drugs often employs conflict paradigms in which the drug effects on punished and unpunished responding can be compared. In this study, a fixed interval schedule generating a range of baseline response rates allowed comparison of the effects of anxiolytic drugs with those of psychotomimetic drugs on equivalent and differing rates of punished and unpunished responding. The first response made by the rat after a 40-s fixed interval elapsed resulted in food pellet delivery.

The psychopharmacology of impulsive behaviour in rats VIII: effects of amphetamine, methylphenidate, and other drugs on responding maintained by a fixed consecutive number avoidance schedule.

Rationale: Impulsive behaviour is a component of psychiatric disorders such as bipolar disorder, attention deficit hyperactivity disorder (ADHD), or personality disorders. Most experimental studies on impulsive behaviour punish impulsive choices by loss or delay of reward. In the present study, impulsive behaviour was punished by an explicitly aversive stimulus, using a novel fixed consecutive number (FCN) schedule of electric shock avoidance.

Effects of a non-peptide CRF antagonist (DMP696) on the behavioral and endocrine sequelae of maternal separation.

We examined whether blockade of corticotropin-releasing factor (CRF) receptors by a non-peptide CRF antagonist (DMP696) would attenuate the stress hyper-responsiveness that occurs in response to maternal separation. In a social interaction test as well as the elevated plus maze, adult male rats, which had been maternally separated as infants, displayed more anxiety-like behavior compared with handled rats. DMP696 increased social interaction in both groups.