Time-dependent improvement of performance on appetitive tasks in mice (original) (raw)

Shifts in the psychophysical function in rats

Behavioural processes, 2007

The primary goal was to compare results from a free operant procedure with pigeons (Machado and Guilhardi, 2000, Experiment 2) with new results obtained with rats. The secondary goal was to compare the results of both experiments with dependent variables that were not used in the original publication. As in the original study with pigeons, rats were trained on a two-alternative free-operant psychophysical procedure in which left lever press responses were reinforced during the first and second quarters of a 60-s trial, and right lever press responses were reinforced during the third and fourth quarters of the trial. The quarters were reinforced according to four independent variable interval (VI) schedules of reinforcement. The VI duration was manipulated in each quarter, and shifts in the psychophysical functions that relate response rate with time since trial onset were measured. The results obtained with rats were consistent with those previously obtained with pigeons. In addition, results not originally reported were also consistent between rats and pigeons, and provided insights into the perception, memory, and decision processes in Scalar Expectancy Theory and Learning-to-Time Theory.

CHANGES OF ANIMAL BEHAVIOR IN TERMS OF INFLUENCE ON MEMORY PROCESSES

In experiments on white rats, changes of behavioral indexes were determined in the open field test, in terms of both impairment and improvement of mnestic reactions, established under influence of electroshock or nootropic medicinal products. Piracetam, arginine-vasopressin (AVP) and sydnocarb (S) (psychomotor stimulant similar in biological effects) were used as investigated medications. It was found that electroshock amnesia of conditioned passive defensive skills (CPAR) was accompanied by a significant inhibition of mobility and duration of grooming in rats. At the same time, animals with lost and retained CPAR were observed to reduce number of researched burrows, reflecting the state of unconditioned reflex activity. Nootropic effect of piracetam was combined with decrease of research activity and AVP effect was combined with inhibition of all forms of behavior determined by methodology used. Improvement of mnestic reactions in terms of a two-week administration of S was accompanied by stable increased mobility of rats, while shifts of other behavioral indexes had a phase character. The deterioration of conditioned reflex memory performance due to S neurotoxic effects 30 minutes after administration on the 3rd and 14th day of course administration, was combined with a steady decrease of research activity and anxiety, 2 weeks after S administration inhibition of mobility and research activity of animals were added.