Serial position effects in social transmission of food preference: retention/demonstration intervals.

The effects of retention and demonstration intervals on serial position were evaluated in two experiments with Long-Evans rats. A list of 3 demonstrators that had eaten one of three flavored foods was presented to naive observers. In Experiment 1, there were four groups, three groups with a retention interval compared with one group with a zero retention interval or no retention interval. In Experiment 2, the demonstration interval was reduced. Intervals of 15, 5, 2, and 1 min were used. In Experiment 1, primacy decreased gradually in the four groups as the retention interval was increased in duration. In Experiment 2, primacy also decreased gradually, and recency occurred with the 1-min demonstrator interval. The increase in the duration of the retention interval reduced primacy. The reduction in the duration of the demonstration interval decreased primacy and produced recency.

Evaluación de un programa de intervención breve motivacional para fumadores: resultados de un estudio piloto / Evaluation of a brief motivational intervention program for smokers: results of a pilot study

Tobacco consumption is a world-wide public health problem that has been associated with different types of cancer, cardiovascular and respiratory diseases, alterations in the reproductive system, dental problems and some eye diseases. In Mexico the National Survey of Addictions (2002) reported that 26.4% of the urban population between 12 and 65 years and 14.3% of the rural population are smokers. The Secretary of Health indicated that more than 53000 people died from diseases related to tobacco consumption. The consumption of tobacco stands among the ten first causes of morbidity and mortality in Mexico. In this sense, smoking is considered as one of the main public health problems in Mexico. Several organisms and institutions have undertaken actions in an attempt to solve it, such as the development of educative programs directed to the general population and programs to help smokers to quit this habit. Some of the main strategies to reduce cigarette consumption include nicotine replacement therapy, therapy not based on nicotine (antidepressants, some opiate antagonists and anxiolytic drugs), psychological programs, and the combination of some of them. Regarding psychological treatments, behavioral and cognitive behavioral techniques for smoking cessation hold empirical evidence about their efficacy for reducing the abuse of substances. In Mexico, psychological, nicotinic and non-nicotinic treatments to stop smoking are used. Nevertheless, the methodological and theoretical grounds of the psychological interventions are not well-established and there are no specific data about the changes in the consumption pattern after the application of the interventions and whether the effects of the treatment stay through the time. Specifically, the information about the efficacy of the brief interventions on smokers in the Mexican population is scarce. Although different studies have demonstrated that the brief motivational interventions are more effective to reduce the abuse of different substances than intensive interventions or no interventions at all, the techniques are not widely used in the treatment of tobacco consumption in Mexican population. With this evidence, the National Autonomous University of Mexico (UNAM) developed the Brief Motivational Intervention Program to treat smokers. The Brief Motivational Intervention is based in the Social Cognitive Theory, the Prevention of Relapses Model, in techniques of motivational interview and self-control techniques. Therefore, the goal of the present research is to evaluate a brief motivational intervention program for smokers. In order to achieve this aim, 10 individuals between 19 and 55 years old participated in the program; five individuals showed low nicotine dependence and five severe nicotine dependence according to the Questionnaire of Fagerström Tolerance. There was a public invitation and the participants consent to participate voluntarily in the <

Serial position effects in social transmission of food preference.

The serial position effect in Long-Evans rats was evaluated in two experiments. In Experiment 1, the effect in a group for which an interstimulus interval (ISI) was introduced between items in a list of demonstrators was compared with that in a group without an ISI. With an ISI, a recency effect was produced. In Experiment 2, a serial position effect group was compared with four groups in which either the distinctiveness or the context of the middle item was changed, relative to the items on either side of it. A von Restorff effect was produced when a rat from a different strain was used as a demonstrator in Position 2. The results for Experiment 1 are discussed in relation to interstimulus effects in monkeys and those for Experiment 2 with respect to changes in the physical properties of middle items.

Sex differences in serotonergic activity in dorsal and median raphe nucleus.

There is evidence on the existence of sex differences in the serotonergic system of the raphe. This study examines sex-based differences in serotonergic activity in the dorsal (DRN) and median (MRN) raphe nucleus; two structures that have consistently been implicated in the brain circuitry associated with fear and anxiety reactions. We also analyzed the effects of the elevated plus-maze (EPM) test, which allows the measuring of behavioral reactions to stress on rats produced by fear to height and open spaces on such sex differences. The present study was carried out on 70- to 80-day-old rats exposed or not to the EPM test. Immediately after the test, or 10-12 days later, groups of animals were sacrificed to measure serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) concentration in the DRN and MRN, to calculate the serotonergic activity ([5-HIAA]/[5-HT]). Serotonergic activity in the female's DRN was consistently higher than in male's DRN. Such differences were not observed in the MRN. While exposed to the EPM test, female rats display more aversive responses than males, only during the day of diestrus 1. After the EPM test, serotonergic activity decreased in the female's DRN and in the male's MRN, both immediately and 10-12 days later. The sex-based differences in fear/anxiety reported in this study could be linked to the observed decrease in serotonergic activity in the DRN of female rats after the EPM test.

Effect of steroid injection to newborn rats on serotonin activity in frontal cortex and raphe.

The effects of injecting testosterone propionate or estradiol benzoate to newborn rats on dopaminergic and serotoninergic activity in the frontal cortex, dorsal and median raphe nucleus were analyzed when animals reached adulthood. High performance liquid chromatography was used to measure tissue levels of dopamine, serotonin and its metabolites. Activity was calculated as the metabolite/neurotransmitter ratio. An increase in androgen or estrogen levels at birth caused a significant decrease in serotoninergic activity in the frontal cortex and in the dorsal raphe nucleus, without causing apparent changes in dopaminergic activity; serotinergic activity in the median raphe nucleus was not affected. The results suggest that the transmission of DA and 5-HT in these structures are differentially influenced by early androgenization or estrogenization.