The medial amygdala: Serotonergic inhibition of shock-lnduced aggression and pain sensitivity in rats

Two aspects of the amygdaloid complex (corticomedial and basolateral) were examined with reference to serotonergic inhibition of shock-induced aggression. Fighting was significantly depressed by serotonergic stimulation (5-HT, 10 μg bilateral) in the corticomedial amygdala while serotonergic blockade (methysergide, 5 μg bilateral) in this region increased levels of fighting. No consistent effects were obtained with serotonergic manipulation of the basolateral amygdala. Further investigation revealed that the state of serotonergic activity in medial amygdaloid sites was associated with concomitant alterations in the animals' sensitivity to footshock. Results are discussed in relation to a) a general inhibitory role of serotonin in behavioural mechanisms and b) a dopaminergic-serotonergic balance for behavioural arousal involving medial amygdaloid nuclei.     

Outline of a denotative definition of aggression

Aggression is defined as generic assertiveness which includes both constructive and destructive behaviors. An attempt is then made to classify the distinctive operational settings (phenotypic situations) which trigger aggression. The classes of such settings are: 1) privation - the frustration of vital needs and the frustration due to inner conflict of needs; 2) conflict (social) - situation-specific competition and intragroup rivalry for dominance; and 3) victimization — predator-prey relations and vandalism per se. Critical questions which emerge from the definition and classification are posed.     

Visual target control of schedule-induced aggression in white king pigeons (columba livia)

Visual target control of schedule-induced attack was studied in domesticated pigeons by exposing them to successive and simultaneous target preference procedures involving a fixed-time food schedule and projected target images. Pigeons preferred attacking an image of a conspecific head over a headless bird regardless of the height of the latter. Images of an intact bird and of a head alone were equally effective in controlling attack and more effective than the headless bird. Neither the eye nor four. other head-related features exclusively controlled attack. The combined results suggest that the head of an intact conspecific target selectively controls schedule-induced attack and that the effectiveness of the head in directing attack is inversely related to its physical integrity as a unit without regard to specific features. These results are consistent with reports that the head and head-related features of an intruder control reproductive aggression in birds.     

The reinforcing value of several types of aggressive behavior: A review

Field observations of “surplus killing” and laboratory studies of operant performance rewarded by prey-killing opportunities suggest that predatory behavior is positively reinforcing. Similarly, both repeated encounter and operant performance studies suggest that intraspecific aggression can be positively reinforcing for successful aggressors. While a few studies suggest that defensive aggression under aversive conditions may also be positively reinforcing, it appears that when appropriate response modes are available escape and/or avoidance are preferred to attack. Studies of the reinforcing properties of aggression-eliciting brain stimulation are in general agreement with these conclusions, but methodological problems with these latter observations render them less compelling. The progressive escalation of aggression seen in “warm-up effects” of birds and fish, “priming effects” of mice, and ecstatic violence of humans may be analogous processes based on the positively self-reinforcing characteristics of some kinds of aggression. The transient reductions of aggression which appear as refractory periods and satiation effects in a variety of species may reflect temporary reductions in the reinforcing value of aggression. All these temporal effects must be considered in the evaluation of experiments on the reinforcing value of aggression. More generally, it is possible that these temporal fluctuations reflect the operation of common motivational processes (aggressive states) which regulate overt aggression by changing its reinforcing value.     

Toward a social psychological profile of would-be rioters

Male ice hockey fans (N = 78) completed a battery of biographical, social, cognitive, and individual differences measures that had previously been administered piecemeal to spectators found in attendance at games. Participants' self-reported likelihood of joining in a crowd disturbance served as the dependent measure. The individual differences measures included physical aggression, anger, impulsivity, psychopathy, sensation seeking, and public self-consciousness. All but public self-consciousness was positively related to subjects' likelihood of escalating a disturbance. Participants' age, number of accompanying males, the false consensus effect, number and recency of fights, and attending in anticipation of watching player fights were also related to the dependent measure. A multiple regression analysis yielded a multiple R = .807, accounting for 65% of the variance. The time since the participant was last in a fight and liking to watch player fights emerged as significant predictors. Aggr. Behav. 24:219–226, 1998. © 1998 Wiley-Liss, Inc.     

Study on the relations between temperament,aggression, and anger in children

The present work analyzes the relationships between the dimensions of temperament and the exteriorized emotions of aggression and anger. Temperament was assessed by mothers using the Dimensions of Temperament Survey‐Revised, while aggression and anger were self‐reported by the children using the Scale of physical and Verbal Aggression and the State–Trait Anger Expression Inventory for Children. The sample studied was made up of 293 children (49.83% boys; 50.17% girls) with a mean age of 11.13 years. The results showed that temperamental difficulties give rise to exteriorized emotions, especially anger. Predictive values of temperament on aggression and anger ranged from 1% to 7% of explained variance. Aggr. Behav. 32:207–215, 2006. © 2006 Wiley‐Liss, Inc.     

The Relation of Perceived Neighborhood Danger to Childhood Aggression: A Test of Mediating Mechanisms

In the current study, two mediational mechanisms, parenting practices and children's beliefs about aggression, were hypothesized to account for the relationship between perceived neighborhood danger and childhood aggression. Using structural equation modeling, data were analyzed from an inner-city school-based sample of 732 predominantly African American 5th graders. Results suggested that perceived neighborhood danger was associated with strong positive beliefs about aggression, which in turn was associated with high levels of aggression. The hypothesized mediating role of parenting practices (restrictive discipline, parental monitoring, and parental involvement) on the relation between perceived neighborhood danger and child aggression was not supported. However, the current findings suggest that children's positive beliefs about aggression mediated the relationship between restrictive discipline and aggression. Directions for future research are discussed.     

Genetic basis for male aggression and survivorship in wild house mice (Mus domesticus)

Work on the genetic region of the house mice known as the t-complex has produced the hypothesis that mice heterozygous for t-haplotypes (+/t) may have a selective advantage over wild-type (+/+) males owing to the greater aggressiveness of +/t males. We tested this hypothesis by examining the behavior of +/+ and +/t mice placed in four large outdoor enclosures. We found that +/t males were dominant over +/+ males. Furthermore, in the outdoor enclosures +/t males had higher survivorship than +/+ males, both as adults and juveniles. However, males of the two genotypes did not differ in home range size. We suggest that t-haplotypes may be, in part, maintained in mouse populations because of a selective advantage in heterozygous males. © 1996 Wiley-Liss, Inc.     

Reactive and proactive aggression: Similarities and differences

The purpose of the current study was to elaborate the nomological net surrounding the constructs of reactive (RA) and proactive aggression (PA). Typically examined in the context of children, the current study utilized a sample of 211 young adults to examine the relations between reactive and proactive aggression and measures of general personality and social information processing, as well as maladaptive behavioral correlates such as crime, substance use, and riskier sex. Both raw and residualized scores were examined. Using raw scores, the primary differences between RA and PA were related to Neuroticism (i.e., RA more strongly related) and externalizing behaviors (i.e., PA more strongly). The authors comment on the similarity of findings when using raw scores and the divergence of findings using residualized scores and argue for a cautious interpretation of differences based on residualized scores. The authors conclude that the role of Neuroticism warrants further exploration as a means for understanding the heterogeneity of aggressive behavior.     

攻击性初中生的类别转变：潜在转变分析

研究采用潜在转变分析探讨了攻击性初中生的类别转变。276名初中参加了为期一年的短期纵向追踪研究,在一年中分两次报告了自己的攻击行为。用潜在转变模型分析了初二到初三时青少年的攻击类别转变,结果表明初中生有三种攻击模式。研究以潜在转变模型进一步探究了这三种攻击模式的变化,结果发现两种模式具有很强的稳定性,不同模式之间也有一定程度的转变。最后,研究探讨了攻击类别转变的影响因素,结果表明性别与友谊质量可以起到显著作用。针对实际意义,文章最后进行了讨论和总结。