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PubMed1989

Central serotonin and impulsive aggression.

The role of central serotonergic (5-HT) system dysfunction in the regulation of aggression in both animals and man has been investigated for more than the past two decades. Evidence for reduced central 5-HT in the mediation of aggression comes from both behavioural and correlative studies. Functional reduction and augmentation of 5-HT activity is respectively associated with increased and decreased aggression in various animal models of aggression. While similar studies in man have not been performed, strong and consistent associations between indices reflecting reduced pre-synaptic 5-HT activity and aggression have been reported. Evidence of post-synaptic receptor upregulation in the brains of suicide victims has also been reported leaving the functional status 5-HT activity in such patients an open question. However, reduced neuroendocrine (i.e. prolactin) responses to fenfluramine, a 5-HT uptake inhibitor/releaser, which activates both pre- and post-synaptic sides of the 5-HT synapse, strongly suggest that overall central 5-HT activity is reduced in mood and/or personality disorder patients with history of suicidal and/or impulsive aggressive behaviour. Preliminary data with the 5-HT receptor agonist m-chlorophenylpiperazine further suggest that reduced activity of post-synaptic 5-HT receptors may be an important correlate of impulsive aggressive behaviour. Pharmacological agents with potent 5-HT pre- and/or post-synaptic augmenting effects should be tested clinically to determine their efficacy in the treatment of impulsive aggressive behaviour in psychiatric patients.

Aggression↗
PubMed1988

Intercommunity differences in aggression among Zapotec children.

Patterns of play aggression and serious aggression were compared in 2 neighboring Zapotec Indian communities that have different levels of adult violence. Social learning theory provided the basis for predicting that levels of agonistic behavior among children would parallel levels of violence among adults. Ethological methods were employed to observe 3-8-year-old children (N = 48). An examination of physical aggression and nonphysical threatening showed that agonism generally was more severe among the children of the more aggressive community. That is, children from the more aggressive community engaged in more actual fighting (p = .005) and play fighting (p = .0001) than their counterparts from the other community. On the other hand, children from the less aggressive community used more noncontact threatening than the children from the more aggressive community (p = .0001). These findings suggest that community differences in levels of violence are perpetuated as Zapotec children learn community-appropriate patterns for expressing aggression and continue to express these patterns as adults. Possible functions of play fighting are also discussed.

Aggression↗
PubMed1986

Social cognition and aggression in delinquent adolescent males.

The relationship of aggression to several social cognitive variables in delinquent adolescent males was investigated. Subjects were fifty-eight institutionalized males identified by peers as high-aggressive or low-aggressive. Participants were administered measures of perspective taking, moral judgment, and person perception. The findings indicated that only perspective-taking ability was significantly related to aggressive behavior in delinquents. High-aggressive delinquents were less able to perceive others' viewpoints than were low-aggressive delinquents. These findings are consistent with previous research concerning perspective taking and aggression, but disconfirm research involving other social cognitive variables and aggression. Results further indicate the importance of studying social cognitive variables as they relate to relevant clinical behaviors.

Adolescent↗
PubMed1979

The relation of conceptual tempo to aggression and its control.

The relationship of conceptual tempo to fantasy and overt aggression and its control was examined in order to test the generalizability of this cognitive style to domains of social and personality functioning. Fifth-grade boys and girls were administered the Matching Familiar Figures Test and a projective measure of fantasy aggression and its control and were rated sociometrically by peers and teachers on physical, verbal, and indirect forms of overt aggression. While reflective and impulsive children did not differ in degree of fantasy aggression expressed, impulsive children, especially boys, were found to exercise less control over their aggressive thoughts than the other 3 conceptual tempo groups. Impulsive and slow-inaccurate children were also more overtly aggressive, especially in comparison with fast-accurates. In addition, fantasy aggression predicted overt aggression in impulsives but not in reflectives. This study presents new evidence that conceptual tempo relates to areas beyond problem solving involving the child's social-emotional makeup.

Aggression↗
PubMed1977

Midbrain interaction with the hypothalamus in expression of aggressive behavior in cats.

The effects of injections of M- and N-cholinergic blocking agents into the antero-medial hypothalamus (HM) and the midbrain central gray (GC) on the aggressive behavior of cats, evoked by microinjections of carbachol into those areas, were investigated in chronic experiments. The influence of pharmacological suppression of the M-cholinergic system in HM on the carbachol-induced aggression response from GC and vice versa was also studied. In the experiments a quantitative method was applied for measuring the specific vocalization - growling, which is a characteristic of aggressive behavior. In the HM and GC areas of the cat the N- and the M-cholinergic systems participated in the control of aggressive behavior, but the M-component dominated in the process. The suppression of M-cholinergic system in GC prevented the appearance of aggressive behavior evoked by injections of carbachol into HM, and the M-cholinergic blockade in HM reduced (by 90 percent) the aggression response evoked by the injections of carbachol into GC. It is concluded that a concurrent action of the hypothalamic and the midbrain cholinergic systems is necessary for the appearance of a fully expressed aggressive behavior. The hypothalamus and the midbrain are probably links of the same functional circuit, and that the control of aggressive behavior is based on a circulatory action between these structures.

Aggression↗
PubMed1983

Safety training: the elimination of avoidance-motivated aggression in dogs.

This study sought to identify the behavioral characteristics and appropriate treatment of a form of instrumental aggression in companion dogs, herein recognized as avoidance-motivated aggression. In Experiment 1, retrospective data on 92 cases of dangerously aggressive dogs demonstrated the avoidance nature of the aggressive response and its intractability to established counterconditioning treatments. In Experiment 2, safety training, a modified avoidance-learning procedure, resulted in complete and permanent elimination of aggression in all of the 36 dogs tested. In addition, it produced extremely extinction-resistant prosocial avoidance responses, significant increases in the dogs' emotional stability, an avoidance-learning and safety acquisition response set, and improvements in measures of the dog's "carriage." Experiment 3 showed how effective safety training is when compared with other behavior modification techniques that, in theory, should have an impact on avoidance-motivated aggression. Experiment 4 demonstrated the critical importance of using the conditioned safety cue as a positive reinforcement. The relationship of avoidance-motivated aggression to other forms of aggression is discussed. The success of safety training compared with the failure of electrical aversion therapy is analyzed. The theoretical concepts of behavioral balance and an avoidance-learning set are presented. Suggestions to improve the effectiveness of counterconditioning for human avoidance-motivated pathologies are offered. All in all, the data seem to suggest that safety training may create in dogs a sense of control over environmental stressors. By teaching the dogs a behaviorally balanced battery of prosocial "coping" responses, they may be developing the canine counterpart of "self-efficacy" or "courage." It is suggested that this cognitive modification may provide the antithesis of "learned helplessness" and may be of prime importance to the success and stability of the results.

Accident Prevention↗
PubMed1983

Factors associated with rape as predictors of laboratory aggression against women.

This study examined the relation between factors associated with "real"-world aggression against women and laboratory aggression. In the first phase of the research, assessment was made of the attitudes about aggression against women and of the sexual responsiveness to rape of 42 male subjects. In the second phase of the research, which subjects believed was a totally independent experiment, aggression was assessed within a Buss paradigm. It was found that the factors assessed in the first phase successfully predicted men's laboratory aggression in the second research phase. The data are interpreted as supporting the construct validity of (a) theory that suggests that common factors underlie varied acts of aggression against women, (b) the measures designed to predict aggressive tendencies, and (c) the methodology of assessing aggression within a laboratory context.

Adult↗
PubMed1982

A differential semantic assay in order to measure aggressiveness.

The Semantic Differential test for aggressiveness consists of 45 phrases depicting situations which may provoke aggression. They are semantically grouped in two categories of covert and of overt aggressiveness. The reliability of the test was verified in a preliminary study, using one group of patients clinically diagnosed as aggressive, and one group of non-aggressive subjects. The means of the two groups' scores were significantly different, 95% of aggressive subjects having greater than 8 unit and only 21% of non-aggressive ones. After the final validation of the test it can be used to diagnose the aggressiveness in Type A behaviour pattern.

Aggression↗
PubMed1981

[Report on some recent findings in research on the etiology of aggression].

Instead of considering aggression as an autonomous instinct, it is preferable to speak of a potential of aggression which can be exploited by several biological functions. Contemporary ethology insists on the instrumental and polyadaptive nature of aggression. It is the aim of the first section of this paper to reveal the close links which exist between aggression, social organization and adaptation to the environment. The second part reviews some results of recent studies on aggression in primates. It is possible to gain certain hypotheses on human aggression from ethological research work. Territoriality for instance may be interpreted as product of the interaction between the human biogram and the environment rather than as a distinctive and omni-present feature of human nature. Even extreme forms of human aggression (cruelty, sadism, slavery) do not necessarily imply an increased potential for aggressive in our species.

Aggression↗
PubMed1993

Dopaminergic involvement in the effects of piracetam on foot shock induced aggression in mice.

The effects of piracetam-a nootropic drug, were studied on foot shock induced aggressive behaviour in mice. Intraperitoneal injection of piracetam resulted in a biphasic response i.e.; initial excitation followed by inhibition of the aggressive behaviour. The initial excitation was observed with only 100 and 50 mg/kg doses of piracetam and not with the lower doses (25 and 12.5 mg/kg). Dopaminergic receptor blocker haloperidol (0.5; 0.25 and 0.12 mg/kg, ip) and pimozide (1.0 mg/kg, ip) produced inhibition of the aggressive behaviour. Lowering of the dose of haloperidol to 0.06 mg/kg resulted in an excitation of the aggressive behaviour. No motor deficit or catalepsy was observed with either haloperidol or pimozide injected in the doses indicated above. Pretreatment of the mice with haloperidol (0.12; 0.25 and 0.5 mg/kg) led to a dose-dependent blockade of the piracetam (100 mg) induced excitation of the aggressive behaviour, but the inhibition of the aggressive behaviour was not blocked by pretreatment with the excitatory dose of haloperidol. Similarly, pimozide (1.0 mg/kg) pretreatment also effectively blocked the excitatory effect of piracetam on aggressive behaviour. The results suggest the involvement of dopaminergic system in the excitatory effects of piracetam on aggressive behaviour. The inhibitory effect of piracetam appears to be independent of this mechanism.

Aggression↗
PubMed1993

The social matrix of aggression. Enactments and representations of loving and hating in the first years of life.

In this paper, we build on a developing body of work that addresses the various contributions to the child's emerging definition of self in the first five years of life. Described is the role of aggression in the shaping of the child's predominant modes of viewing and experiencing the world. How aggression toward another mixes with desire for another in the formation of early capacities for object relatedness is a central question for any developmental theory of aggression, for aggression is first experienced, shaped, refined, and remodeled in the context of loving relations. Studies from related disciplines provide observational data about how aggression is modified in the first five to six years of life and how the capacity to interpret the intentions of others is crucial to those modifications. Understanding the intentions of others relates also to the capacity to attribute affects, beliefs, and other mental states to others, a capacity referred to elsewhere as a theory of mind. The ability to reflect upon thoughts and feelings in oneself and others provides children with a fuller range of responses to their own and others' perceived aggression. Finally, external experiences of violence, abuse, and deprivation influence the child's experience of his own and others' aggression and prevent the normal modulation of aggression in the social matrix.

Aggression↗
PubMed1996

Do mitigating circumstances influence family reactions to physical aggression?

The influence of mitigating circumstances on family reactions to physical aggression was investigated. 40 families, each with a 2- and a 4-year-old child, were observed during home interactions, and parents' and older children's beliefs concerning mitigation were also assessed. Although parents considered sibling physical aggression to be a serious transgression, they believed that mitigated aggression of both of their children was more excusable and they intervened less often to prohibit mitigated than nonmitigated aggression, even when the aggression was severe. Older children also believed that mitigated aggression deserved less punishment. Provocation, reciprocity, and lack of aggressive intent occurred as mitigating circumstances in the observations. When family members' reactions to these individual circumstances were examined, discrepancies arose in judgments of which specific mitigations justified aggression. These findings were discussed in terms of the clarity of a parent's message, children's appraisals of it, differing conflict roles, and society's impact.

Aggression↗
PubMed1997

The early socialization of aggressive victims of bullying.

This study reports the first prospective investigation of the early family experiences of boys who later emerged as both aggressive and bullied (i.e., aggressive victims) during their middle childhood years. It was hypothesized that a history of violent victimization by adults leads to emotion dysregulation that results in a dual pattern of aggressive behavior and victimization by peers. Interviews with mothers of 198 5-year-old boys assessed preschool home environments. Four to 5 years later, aggressive behavior and peer victimization were assessed in the school classroom. The early experiences of 16 aggressive victims were contrasted with those of 21 passive (nonaggressive) victims, 33 nonvictimized aggressors, and 128 normative boys. Analyses indicated that the aggressive victim group had experienced more punitive, hostile, and abusive family treatment than the other groups. In contrast, the nonvictimized aggressive group had a history of greater exposure to adult aggression and conflict, but not victimization by adults, than did the normative group, whereas the passive victim group did not differ from the normative group on any home environment variable.

Adult↗
PubMed1997

Inhibition of neuronal nitric oxide synthase increases aggressive behavior in mice.

BACKGROUND: Mice with targeted disruption of the gene for the neuronal isoform of nitric oxide synthase (nNOS) display exaggerated aggression. Behavioral studies of mice with targeted gene deletions suffer from the criticism that the gene product is missing not only during the assessment period but also throughout development when critical processes, including activation of compensatory mechanisms, may be affected. To address this criticism, we have assessed aggressive behavior in mice treated with a specific pharmacological inhibitor of nNOS. MATERIALS AND METHODS: Aggressive behavior, as well as brain citrulline levels, were monitored in adult male mice after treatment with a specific nNOS inhibitor, 7-nitroindazole (7-NI) (50 mg/kg i.p.), which is known to reduce NOS activity in brain homogenates by > 90%. As controls, animals were treated with a related indazole, 3-indazolinone (3-I) (50 mg/kg i.p.) that does not affect nNOS or with on oil vehicle. RESULTS: Mice treated with 7-NI displayed substantially increased aggression as compared with oil- or 3-I-injected animals when tested in two different models of aggression. Drug treatment did not affect nonspecific locomotor activities or body temperature. Immunohistochemical staining for citrulline in the brain revealed a dramatic reduction in 7-NI-treated animals. CONCLUSIONS: 7-NI augmented aggression in WT mice to levels displayed by nNOS- mice, strongly implying that nNOS is a major mediator of aggression. NOS inhibitors may have therapeutic roles in inflammatory, cardiovascular, and neurologic diseases. The substantial aggressive behavior soon after administration of an nNOS inhibitor raises concerns about adverse behavioral sequelae of such pharmacological agents.

Aggression↗
PubMed1996

Histological analysis of aggressiveness and responsiveness in Wilms' tumor.

The clinical behavior and outcome for any neoplasm are determined originally by its aggressiveness. As adjuvant therapy becomes increasingly effective for that neoplasm, responsiveness to therapy assumes a larger role in determining outcome. Wilms' tumor (WT) provides instructive examples of the dissociation of aggressiveness from responsiveness. The presence of gigantic nuclei with multipolar mitotic figures (anaplasia) appears to be a marker of resistance to therapy, but not of increased aggressiveness. For this reason, anaplasia in a stage 1 WT and anaplasia confined to discrete foci within the primary tumor have no adverse prognostic significance following surgical resection. The prognostic significance of anaplasia is apparently limited to those patients in whom anaplastic cells remain following attempted surgical resection. WT with predominantly epithelial differentiation usually have a low degree of aggressiveness. In this study, 81.3% of WT with this pattern were stage 1. This feature accounts for the high cure rate associated with this pattern prior to the advent of effective adjuvant therapy. However, epithelial predominant WT that present with advanced stage disease may be quite resistant to therapy, with relapse and death rates higher than for more aggressive WT patterns. In contrast, the diffuse blastemal pattern is associated with marked aggressiveness, but with high survival rates suggesting it is usually responsive to current therapy. These features illustrate the independence of aggressiveness and responsiveness in determining outcome for some patients with cancer. Grading systems must be reevaluated with each significant change in therapy. In order to formulate rational therapy, it is important to determine whether prognostic markers are associated with aggressiveness or responsiveness.

Anaplasia↗
PubMed2005

The activation of raphe serotonergic neurons in normal and hypoarousal-driven aggression: a double labeling study in rats.

The serotonergic system is well known for its aggression lowering effects. It has been shown repeatedly, however, that the serotonergic system is activated during fights, and recent data suggested that it is necessary for the expression of aggressive behavior. We investigated the interaction between serotonergic activation and aggressive behavior by assessing the co-localization of the c-Fos signal (marker of neuronal activation) with tryptophan-hydroxylase activity (marker of serotonin secretion) in the raphe. Control rats were compared with rats exposed to visual and olfactory (but not physical) contacts with opponents (psychosocial stimulation) as well as with rats exposed to aggressive encounters. Fights were accompanied by the activation of the raphe; however, the effect was not aggression-specific, as a similar activation was induced by psychosocial contacts. The lack of behavioral specificity in activation suggests that it was related to social arousal rather than to the execution of fights. The activation of serotonergic raphe neurons showed a negative correlation with aggressive behavior, which is in line with the widespread view that serotonin neurotransmission downregulates aggressive behavior. The activation of serotonergic neurons did not show a correlation with measures of hypoarousal-driven abnormal aggression, which indicates that factors other than the raphe control this behavior. The latter finding may explain the low efficacy of serotonergic treatments in conduct and antisocial personality disorders, in which violence correlates with hypoarousal.

Adrenalectomy↗
PubMed2001

Effects of aggression and wing removal on brain serotonin levels in male crickets, Gryllus bimaculatus.

When pairs of adult male crickets (Gryllus bimaculatus) that had been housed individually for 7 days were placed together, they fought, and dominant-subordinate relationships were formed within 1min. Aggressive behavior by the dominant male was repeated during the period in which the two males were kept together. Immediately after 10min of aggressive interaction, brain serotonin (5-hydroxytryptamine, 5-HT) levels were unchanged in dominant males and significantly reduced in subordinate males. The emission of aggressive song by dominant males is known to be abolished by removal of the wings. All wings were thus removed from male crickets. After 7 days of isolation, pairs of wingless males were placed together. The wingless males fought and formed dominant-subordinate relationships within 1min. The wingless, dominant males displayed aggressive behavior. Brain 5-HT levels in the wingless males were reduced immediately after 10min of aggressive interaction, and no significant differences in brain 5-HT levels were detected between the dominant and subordinate males, unlike the case for intact males. These data indicate a difference in brain serotonergic activity between dominant and subordinate male crickets during aggressive interaction, and suggest that aggressive behavior by dominant male crickets rapidly reduce brain 5-HT levels in subordinate ones. Furthermore, the data suggest that aggressive song is responsible for the change in brain 5-HT levels.

Journal Article↗
PubMed1998

MIB-1 labeling indices in benign, aggressive, and malignant meningiomas: a study of 90 tumors.

Predicting tumor behavior in meningiomas based on histology alone has been problematic. This study retrospectively compares histology and MIB-1 (cell proliferation marker) labeling indices (LI) in benign, aggressive, and malignant meningiomas. Six histological features, including mitoses, necrosis, loss of pattern, hypervascularity/hemosiderin deposition, prominent nucleoli, and nuclear pleomorphism, were compared in 90 meningiomas (Fisher's exact test). Tumors with two or more of the above features were designated as aggressive meningiomas. Malignant meningiomas were characterized by brain invasion or metastasis. The MIB-1 LIs (% positive tumor cell nuclei) were compared between the three groups (Kruskal-Wallis test, Wilcoxon two-sample test). Of the benign meningiomas (n=37; mean age, 54 years), 41% had one of the six histological features, with nuclear pleomorphism (n=10) being the most frequent. The aggressive tumors (n=29; mean age, 61 years) were characterized by nuclear pleomorphism (n=28), mitoses (n=20), necrosis (n=16), loss of pattern (n=16), prominent nucleoli (n=6), and hypervascularity/hemosiderin deposition (n=5). Malignant tumors (n=24; mean age, 59 years) were characterized by nuclear pleomorphism (n=22), mitoses (n=21), loss of pattern (n=21), necrosis (n=21), nucleoli (n=17), and hypervascularity/hemosiderin deposition (n=3). Significant differences were found between the aggressive and malignant groups with regard to loss of pattern, necrosis, and nucleoli (P=.0043, .011, and .00029, respectively). Mean MIB-1 LIs for the benign, aggressive, and malignant groups were 1.0% (range, 0 to 5.5%),5.5% (range, 0.1 to 32.5%), and 12.0% (range, 0.3 to 32.5%), respectively. Differences in the mean MIB-1 LI between groups were statistically significant, with P values of <.0001 (benign v aggressive) and .0012 (aggressive v malignant). Mean MIB-1 LIs for recurrent versus nonrecurrent tumors were 7.1% (range, 0 to 32.5%) versus 3.8% (range, 0 to 20.9%) (P=.32). The mean MIB-1 LI for patients who were alive with or without tumor was 6.2% (range, 0 to 32.5%) versus a mean MIB-1 LI of 14.2% (range, 2.8% to 32.5%) for patients who died of or with tumor (P=.0013). In conclusion, (1) There is a statistically significant difference in the increasing MIB-1 LI means between benign, aggressive, and malignant meningiomas and between patients who were alive versus those who died; (2) there is some overlap in MIB-1 LI ranges between groups, which warrants caution in interpreting an individual MIB-1 LI in a given tumor.

Adolescent↗