Antonio P. Candido

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The aim of the present experiments was to study the effect of nonselective electrolytic lesions of the rat dorsal hippocampus on 2 learning phenomena: the L.J. Kamin (1969) blocking effect and latent inhibition of taste aversion learning. Bilateral dorsal hippocampal lesions selectively impaired blocking induced by 1 saccharin-lithium chloride pairing(More)
The effect of administration of diazepam on successive negative contrast in one-way avoidance learning was examined in rats. Contrast was induced by shifting rats from a large reward, 30 s spent in the safe compartment, to a small reward, 1 s spent in the safe compartment. IP administration of 2 mg/kg diazepam eliminated this negative contrast. Moreover,(More)
The successive negative contrast effect on one-way avoidance was induced by shifting rats from a large reward (30 s spent in the safe compartment after completion of the avoidance response, pre-shift phase) to a small reward (1 s, post-shift phase). Under these conditions, the previously learned avoidance response deteriorated (negative contrast) when(More)
BACKGROUND The Stimulus Preceding Negativity (SPN) is a non-motor slow cortical potential elicited by temporally predictable stimuli, customarily interpreted as a physiological index of expectancy. Its origin would be the brain activity responsible for generating the anticipatory mental representation of an expected upcoming event. The SPN manifests itself(More)
In one experiment half of the animals were trained to avoid a signaled footshock by jumping (30 or 160 trials), whereas the rest of the animals received the same events as yoked. For all of them the termination of the warning signal and of the shock was followed by a safety signal. Several tests were conducted to assess the ability of the stimuli to(More)
The main aim of the present work was to investigate the effect of buspirone, a 5-HT1A receptor agonist, on successive negative contrast in one-way avoidance learning. Successive negative contrast was induced by shifting rats from a large reward (30 s spent in the safe compartment) to a small reward (1 s). Acute administration of buspirone (0.25, 0.5, 0.75(More)
The relationship between hippocampal function and aging was explored in Wistar rats using taste aversion learning by comparing the performance of adult dorsal hippocampal lesioned and fifteen-month-old intact rats with that of adult intact rats. In experiment 1 the conditioned blocking phenomenon was absent in the hippocampal and the aging rats. Unlike the(More)
In three experiments, successive negative contrast was examined in one-way avoidance learning. Reward magnitude in first (pre-shift) and second (post-shift) phases was manipulated by time spent in the safe compartment. Experiment 1 demonstrated that when time in the danger compartment was held constant, a group shifted from a large reward--30 sec spent in(More)
The inbred RLA (Roman Low-Avoidance) and RHA (Roman High-avoidance) rat strains have been psychogenetically selected for rapid (RHA) vs. extremely poor acquisition (RLA) of two-way active avoidance. As a consequence of this selective breeding, RLA animals exhibit a higher level of emotionality that can be observed in many anxiety models. The present study(More)
The main aim of this work was to show the impact of preexisting causal beliefs on causal induction from cause-effect co-occurrence information, when several cues compete with each other for predicting the same effect. Two different causal scenarios -- one social (a), the other medical (b) -- were used to check the generality of the effects. In Experiments(More)