Featured research (5)
In three experiments with rats, we analyzed the potential anxiolytic effects of sodium valproate, an anticonvulsant drug that has shown additional pharmacodynamic effects in animal models, including anxiolytic action. Since previous results have revealed that injecting valproate before allowing animals to consume a novel flavor solution resulted in an attenuation of neophobia, we predicted a similar effect when the novel flavor is presented on a drug-free trial in the presence of a context previously associated with the drug. In line with this hypothesis, in our first experiment we observed a reduction in neophobia to a novel flavor for those animals tested in the presence of the context associated with Sodium Valproate. However, a control group that received the drug before being allowed access to the novel flavor showed a significant reduction in consumption. Experiment 2 revealed that the unconditioned effects of the drug include a deleterious effect on the animals' locomotor activity that probably interferes with drinking behavior. Finally, in a third experiment, we directly tested the potential anxiolytic properties of sodium valproate by injecting the drug before implementing a fear conditioning procedure. These findings are explained in terms of the unconditioned anxiolytic action of the drug and the formation of an association between the context and the effects of the drug that evokes a conditioned response reminiscent of such anxiolytic effect.
Repeated pairings of a neutral context and the effects of haloperidol give rise to conditioned catalepsy when the context is subsequently presented in a drug-free test. In order to confirm whether this response is based on Pavlovian processes, we conducted two experiments involving two manipulations that affect conditioning intensity in classical conditioning procedures: time of joint exposure to the conditioned and the unconditioned stimulus, and the length of the inter-stimulus interval (ISI). The results revealed that both an increase in the length of context-drug pairings during conditioning and a reduced ISI between drug administration and context exposure increased conditioned catalepsy. These results are discussed in terms of the temporal peculiarities of those procedures that involve drugs as the unconditioned stimulus along with the role of Pavlovian conditioning in context-dependent catalepsy.
Este libro se enmarca en la colección Investigación e intervención en Psicología e incluye ocho capítulos escritos por jóvenes investigadores que trabajan o han trabajado en el Laboratorio de Conducta Animal y Neurociencia de la Facultad de Psicología de la Universidad de Sevilla. En estos capítulos se conjuga la tradición de investigación que se ha venido desarrollando en los últimos treinta años en el laboratorio con esa visión innovadora que aporta el entusiasmo del que acaba de llegar a un terreno tan apasionante como es la investigación en Psicología Comparada y en Neurociencia
The consummatory successive negative contrast (cSNC) task typically involves administering food-deprived rats 10 daily 5-min sessions of access to 32 % sucrose (preshift) followed by a few sessions in which the concentration is reduced to 4 % sucrose (postshift). Such sucrose downshift leads to transient suppression of consummatory behavior. Reward downshifts were used to determine whether food-deprived rats treat sucrose solutions as food, because sweetness is a proxy for its caloric content, or as water, because a solution has hydration content. In Experiment 1, a cSNC effect was obtained in food-deprived animals, but not in water-deprived animals. This suggested that food deprivation focused attention on the feeding dimension of sucrose, whereas water deprivation focused attention on the drinking dimension of sucrose. Sucrose downshift results in a greater caloric change than in hydration content because both concentrations continue to provide fluid. Experiments 2 and 3 offered presession access to rewards either before preshift or before postshift sessions, respectively. Consistent with this attentional view, presession access to water (which should focus attention on the feeding dimension), but not to food (which should focus attention on the drinking dimension), suppressed consummatory behavior after a sucrose downshift. Presession access to food, like water deprivation, enhanced the hydration properties of the sucrose solution at the expense of its caloric properties. These results are consistent with an attentional hypothesis according to which the internal state, manipulated via deprivation or presession reward access, determines which dimension of the sucrose reward would control consummatory behavior.
Dopamine antagonist drugs have profound effects on locomotor activity. In particular, the administration of the D2 antagonist haloperidol produces a state that is similar to catalepsy. In order to confirm whether the modulation of the dopaminergic activity produced by haloperidol can act as an unconditioned stimulus, we carried out two experiments in which the administration of haloperidol was repeatedly paired with the presence of distinctive contextual cues that served as a Conditioned Stimulus. Paradoxically, the results revealed a dose-dependent increase in locomotor activity following conditioning with dopamine antagonist (Experiments 1) that was susceptible of extinction when the conditioned stimulus was presented repeatedly by itself after conditioning (Experiment 2). These data are interpreted from an associative perspective, considering them as a result of a classical conditioning process.
Maria Angeles Cintado