Dissociation between appearance and location within visuo-spatial working memory

Previous research has demonstrated separation between systems supporting memory for appearance and memory for location. However, the interpretation of these results is complicated by a confound occurring because of the simultaneous presentation of objects in multiple-item arrays when assessing memory for appearance and the sequential presentation of items when assessing memory for location. This paper reports an experiment in which sequential or simultaneous modes of presentation were factorially manipulated with memory for visual appearance or memory for location. Spatial interference (tapping) or visual interference (dynamic visual noise) were presented during retention. Appearance versus location interacted with the type of interference task, but mode of presentation did not. These results are consistent with the view that different subsystems within visuo-spatial working memory support memory for appearance and memory for location.     

Role reversal changes during the ontogeny of play fighting in male rats: Attack vs. defense

From weaning until sexual maturity, the rates at which young male rats hold each other supine during play fighting appear to become progressively asymmetrical. These changes have been previously thought to reflect an initial lack of dominance and a later development of dominance-subordinance relationships. In this paper it is shown that pairs of male rats exhibit asymmetries in playful attack and playful defense throughout development. The changes, resulting in greater asymmetry of pinning rates, are shown to result from age-dependent changes in defensive tactics; the relationship, therefore, remains constant while the form of the behavior changes. Furthermore, it is not the animals showing the highest rates of playful attack who become dominant in older ages.     

Targets and tactics of agonistic and precopulatory behavior in montane and prairie voles: Their relationship to juvenile play-fighting

Play-fighting by juvenile montane and prairie voles involves attack and defense of the head, neck and shoulders. Since during play animals typically borrow behavior patterns from other functional contexts, two adult behavioral contexts were compared to juvenile play-fighting. These were serious fighting and sexual encounters. During serious fighting in a resident-intruder paradigm, most bites are directed at the rump and lower flanks. During sexual encounters, especially in precopulatory behavior, the head, neck and shoulders are gently contacted. Therefore, play-fighting by juveniles would appear to involve attack and defense of areas of the body contacted in adult precopulatory behavior, not adult fighting. Furthermore, the species-specific differences in juvenile play-fighting were also found to be matched by species-specific differences in precopulatory behavior. In both playful and precopulatory encounters, montane voles contacted the head and used upright defensive behaviors more often than prairie voles. In contrast, prairie voles made mutual contact more often and were more likely to rotate to supine in defense of contact to the nape and head. These findings support our hypothesis that juvenile play-fighting in muroid rodents involves the precocial expression of precopulatory, not agonistic behavior.     

Neonatal testosterone augmentation increases juvenile play fighting but does not influence the adult dominance relationships of male rats

Neonatal male rats were either injected subcutaneously with testosterone propionate (TP) or oil vehicle. When weaned, each treated pup was paired with an untreated male sibling. The play fighting of TP-and oil-treated rats were compared at the juvenile phase (30–36 days), and in adulthood (84–90 days). In the juvenile phase, the rate of initiating playful attacks was significantly greater for TP-treated rats. Playful defense in response to such attacks did not differ between TP- and oil-treated rats. At the completion of the study, cortical thickness was measured for all the groups of rats. Oil treatment decreased overall cortical thickness relative to untreated pairmates, whereas TP treatment did not. Both oil and TP treatment abolished the asymmetry in hemispheric thickness, which was present in the untreated pairmates. The reversal of at least one of these injectioninduced changes in the cortex by TP provided independent evidence for the effectiveness of the TP treatment. As adults, neither the TP treatment nor the oil treatment influenced which pairmate became dominant. Dominance was judged by which pairmate initiated less playful attacks. Therefore, it is concluded that the early neonatal testosterone surge is not likely to be a factor in influencing the behaviors that lead to adult dominance. In contrast, play fighting is influenced by hormonal events in this early neonatal phase. It thus appears that play fighting and the aggressive systems subserving dominance relationships are differentially controlled. © 1992 Wiley-Liss, Inc.     

Juvenilized play fighting in subordinate male rats

As pairs of male juvenile sibling rats that are housed together become sexually mature, they develop a dominance-subordinance relationship. These dominance relationships appear to be reflected in the play fighting of the pairmates both as juveniles and as young adults, in that the seemingly subordinate partner initiates more playful attacks at both ages. However, as adults, even though it is the subordinate that initiates more playful attacks, it is the subordinate that is pinned on his back by the partner most often. Dominant pairmates were found to switch to defensive patterns typically found in adult males. In contrast, the subordinates, when contacted on the nape, were more likely to retain the juvenile pattern of turning over to supine. Therefore, the subordinate pairmate of an adult pair of male siblings both initiates more playful attacks and defends itself in a more juvenile manner than its dominant partner, and this leads to it being pinned more frequently. This pattern of behavior by subordinate rats is suggested to function as a friendship maintenance mechanism permitting co-existence in multimale colonies.     

Differences in protective factors of substance use in early and middle adolescence

This study focuses on possible differences in protective factors of substance use in early and middle adolescence. These possible differences are analysed by means of the same structural equation model applied to two different samples of adolescents: the first sample is made up of 450 adolescents, ages 12 to 14 years, and second of 203 adolescents, ages 15 to 17 years. The results indicate that adequate family communication is a protective factor in both samples, whereas high social self-esteem is proposed as a risk factor in middle adolescence. The adolescent's family self-esteem and attitudes towards authority are also relevant factors in both samples. These results may have important implications in the development of future intervention programmes.     

AIDS‐NGOs and political participation: Brazilian and Canadian experiences

Non‐governmental organizations (AIDS‐NGO) are an instrument of political pressure and assistance, often serving as a life reconstruction aid for people living with HIV/AIDS. In this case study, we analyze data from historical documents, in‐depth interviews, and questionnaires obtained from participants and community agents in two AIDS‐NGOs: one in Canada (NGO‐Ca), and another in Brazil (NGO‐Br). Despite contextual differences, both NGOs are involved in a fight against stigma and discrimination that may aggravate existing social exclusion. Variances in political participation are nevertheless evident. In NGO‐Ca, efforts are directed towards maintaining and consolidating human and social rights. In NGO‐Br, the primary goal is building these. In NGO‐Ca, the participant is part of a structured organization where he or she receives the required supports; the NGO is thus a service provider. Conversely, in NGO‐Br, the participant is both the actor and author of collectively constructed supportive actions. It is hoped that the lessons learned from this limited case study will assist in the strengthening of AIDS‐NGO organization and activity, particularly in the developing world context. Copyright © 2008 John Wiley & Sons, Ltd.     

Effects of different substance misuse in genital reflexes of paradoxical sleep deprived male rats

As psychostimulants are widely abused, their neurochemical and behavioral effects have been extensively studied for many years. Our previous data demonstrate that paradoxical sleep deprivation (PSD) enhances drug-induced penile erection and ejaculation. PSD in association to drugs of abuse like cocaine potentiated genital reflexes in male rats. In this sense, the present study investigated if three substances abused by young people--such as Delta(9)-tetrahydrocannabinol (Delta(9)THC), alcohol and caffeine--had any significant effect on the genital reflexes in PSD rats. The results indicated that PSD induced erection in 50% of the rats and 20% ejaculated. In addition, there was no significant alteration in the number of animals exhibiting genital reflexes neither on the frequency of these behaviors when challenged with Delta(9)-THC or alcohol or caffeine after 96 h of PSD. These findings show that Delta(9)THC, alcohol and caffeine when administrated isolated did not produce alterations in genital reflexes in the PSD male rats.