Performance on a Mirror-Drawing Task by Non-Right-Handers

Left-, mixed-, and right-handed (each n = 10, N = 30) adolescent boys who were classified on the basis of a hand preference inventory performed a mirror-drawing task with a bilateral transfer of a skill paradigm. Participants' hand preference and the magnitude of bilateral transfer of skill were assessed in terms of errors committed and time taken to complete the mirror-drawing task. Mixed-handed participants exhibited significantly less habit interference for mirror drawing, and they performed the task significantly faster than the left-handers did; the group difference was not significant for the frequency of errors committed. These groups did not differ in terms of the magnitude of bilateral transfer of skill; the trend, however, showed that the transfer of skill was minimum in mixed-handers. These findings extend the theory that mixed-handed participants' inability to transfer motor skill from one hand to the other could be attributable to their lack of a clear pattern of lateralization. Their ability to perform well either at initial or later trials may be a function of less interference from their normal motor habits.     

A new Method for Determining Reliability Coefficient: The Consistency Index

It was predicted that murderers would differ in their body-image boundary dimensions from attempted suicides. It was found that the murderers obtained lower barrier scores, which was in opposition to the prediction, and lower penetration scores, which was in agreement with the prediction. Overall, therefore, the prediction was not supported.     

Income maximizing in concurrent interval-ratio schedules

Three mice chose between concurrent variable-ratio variable-interval schedules to produce a warm air stream while they were housed in a cold chamber. Across conditions, the duration of the warm air stream was varied between 10 and 80 s and was equal for both schedules. Preference for the VI schedule covaried with reinforcer duration as predicted by maximizing accounts of choice.     

Maze-running and thigmotaxis in mice: Applicability of models across the sexes

Both male (n = 244) and female (n = 223) Swiss albino mice displayed a U-shaped pattern of thigmotaxis (wall-seeking) in a circular open-field (OF) before and after a daily maze-running. A significant increase of mice's tendency to occupy the inner partitions of the OF after the maze trial on the last three out of five days of training was observed. When factor analyzed, the variables indicating the wall-seeking behaviour of both sexes were divided into two factors interpreted as "spontaneous" in conjunction with the first three to four maze trials and as "learning-related thigmotactic behaviour" during the subsequent trials in the course of the learning process.     

An ethopharmacological assessment of agmatine's effects on agonistic encounters between male mice

The endogenous polyamine agmatine may be a new central neurotransmitter. Agmatine‐like immunoreactivity has been described in numerous brain regions (such as the hypothalamus and amygdala), long thought involved in the control of aggression. Consequently, the present study examined agmatine's (2.5–80 mg/kg, ip) effects on behavior directed by isolated male mice to anosmic partners in a neutral area. The videotaped encounters were analysed in terms of 10 broad behavioral categories. Agmatine did not appear to be involved in the modulation of aggression or anxiety in this test. Aggr. Behav. 31:000000, 2005. © 2005 Wiley‐Liss, Inc.     

Behavioral profile of L–741,741, a selective D4 dopamine receptor antagonist,in social encounters between male mice

Although the role of dopamine D1–D2–D3 receptors in the modulation of aggression has been extensively documented, there is not information with respect to the implication of D4 receptor. The aim of this study was to examine the acute effects of L–741,741 (0.75, 1.5 and 3 mg/kg, i.p), a selective D4 receptor antagonist, on social encounters between male mice using an ethopharmacological approach. Ten min of diadic interactions were staged between a singly housed and an anosmic mouse in a neutral area. These encounters were videotaped and the accumulated time allocated by subjects to ten broad behavioral categories was estimated. Besides other behaviors, the aggressive and motor behaviors were evaluated 30 min after injection using an ethologically based analysis. L–741,741 did not affect significantly offensive behaviors (threat and attack), as compared with the control group. Likewise, motor and anxiety‐related behaviors (such as social investigation, avoidance/flee or defense submission) were not altered after drug administration. These results suggest that dopamine D4 receptor is not involved in the modulation of aggressive behavior. Aggr. Behav. 29:552–557, 2003. © 2003 Wiley‐Liss, Inc.     

Effects of acute,subchronic and intermittent MDMA (‘ECSTASY’) administration on agonistic interactions between male mice

Recent studies suggest that acute administration of 3,4‐methylenedioxymethamphetamine (MDMA), an amphetamine derivative popularly known as “ecstasy,” produces an antiaggressive effect in male mice. However, there is no evidence with respect to the development of tolerance or sensitization after its subchronic or intermittent administration. In this study, we examined the action of low to moderate doses of MDMA (1.25, 2.5 and 5 mg/kg, i.p), administered acutely, subchronically (for 7 days) or intermittently, on agonistic behavior elicited by isolation in male mice. Individually housed mice were exposed to anosmic “standard opponents” 30 minutes after the drug administration, and the encounters were videotaped and evaluated using an ethologically based analysis. Acute treatment with MDMA provoked a significant reduction of aggressive behaviors, without altering immobility. However, this action was only selective at 1.25 mg/kg. With the intermediate (2.5 mg/kg) and the highest doses (5 mg/kg) of the drug, it was observed a significant decrease of offensive behaviors, accompanied by an increase of exploration from a distance, avoidance/flee and defense/submission behaviors. This ethopharmacological profile could indicate the existence of an anxiogenic‐like effect of MDMA. The overall picture of the effects of MDMA was very similar in the acutely, intermittently and daily treated animals. No tolerance or sensitization to the actions of the drug was developed after its repeated or intermittent administration.     

Effects of prenatal cocaine and genotype on intermale agonistic behavior in Mus musculus

We exposed the pups of three F₁ genotypes of mice to a daily regime of cocaine by injecting their mothers (all C57BL/10J strain) on days 7–18 of gestation with 20 mg/kg subcutaneously. Pups of the cocaine and control groups did not differ on measures of maternal and pup health or size. Male pups were weaned and isolated at 21 days of age and their behaviors measured in an intermale aggression situation at about 80 days of age. Treated and untreated males of each F₁ genotype were paired in dyads with either a C3H/HeJ (hawk-like) or AKR/J (retaliator-like) standard tester male. Standard tester males were not exposed to cocaine. Cocaine treatment alone reduced the overall level of aggression in dyads, and in interaction with genotype or the standard tester it altered the behavior of dyads in all phases of social interaction: the initiation, content, and outcome. Standard testers used as behavioral probes, differentiated cocaine and control males with respect to their stimulus and behavioral qualities. Aggr. Behav. 23:183–196, 1997.© 1997 Wiley-Liss, Inc.     

Association between intermale aggression and genetically-defined tryptophan hydroxylase activity in the mouse brain

The relationship between the genetically defined intensity of intermale aggression and the activity of brain tryptophan hydroxylase (TPH) has been studied in inbred mice. No association between the enzyme activity and the percentage of aggressive mice (reflecting the predisposition to aggressive reaction) was revealed. However, a significant positive interstrain correlation between brain TPH activity and accumulated attacking time (reflecting fight intensity) was identified. No correlation was found between TPH activity and the accumulated attacking time in segregating F2 (BALB × C57BL) mice. In conclusion, TPH is an important, but not the only factor controlling the intensity of intermale aggression in mice. © 1996 Wiley-Liss, Inc.     

Gender-specific social experiences and the development of aggressive and sexual behavior in male mice

This study examined influences of gender-specific social experiences on the development of aggressive and sexual behavior in male mice. To determine the effects of gender-specific social experience three different types of groups were constituted after the animals had been weaned. The subjects were randomly assigned to different treatments. Female groups were composed of one experimental male and three female cohabitants. Male groups were composed of five experimental males each, and the mixed-sex groups were composed of two experimental males and of two females. The experimental subjects stayed in these groups until the age of approximately three months, when the testing for sexual and aggressive behavior commenced. For the sexuality tests, a receptive female was placed in the home cage of the experimental male for ten minutes. A nonaggressive male was placed in the home cage of the experimental male for seven minutes for the aggression tests. The experimental males were administered both sexuality and aggression tests, the sequence of testing sexual and aggressive behavior was systematically varied in order to control the influence of the two different types of behavioral tests. The results showed that males with only male social experiences showed fewer responses and were less active in both the aggression and sexuality tests than the males from the two other types of groups. Significant positive correlations between activity during aggression and sexual tests were obtained for all three groups. © 1994 Wiley-Liss, Inc.