Vulnerable Body Parts Research Articles

Effects of resocialization on post‐weaning social isolation‐induced abnormal aggression and social deficits in rats

As previously shown, rats isolated from weaning develop abnormal social and aggressive behavior characterized by biting attacks targeting vulnerable body parts of opponents, reduced attack signaling, and increased defensive behavior despite increased attack counts. Here we studied whether this form of violent aggression could be reversed by resocialization in adulthood. During the first weak of resocialization, isolation-reared rats showed multiple social deficits including increased defensiveness and decreased huddling during sleep. Deficits were markedly attenuated in the second and third weeks. Despite improved social functioning in groups, isolated rats readily showed abnormal features of aggression in a resident-intruder test performed after the 3-week-long resocialization. Thus, post-weaning social isolation-induced deficits in prosocial behavior were eliminated by resocialization during adulthood, but abnormal aggression was resilient to this treatment. Findings are compared to those obtained in humans who suffered early social maltreatment, and who also show social deficits and dysfunctional aggression in adulthood.

Experimental mechanical characterization of abdominal organs: liver, kidney & spleen

Abdominal organs are the most vulnerable body parts during vehicle trauma, leading to high mortality rate due to acute injuries of liver, kidney, spleen and other abdominal organs. Accurate mechanical properties and FE models of these organs are required for simulating the traumas, so that better designing of the accident environment can be done and the organs can be protected from severe damage. Also from biomedical aspect, accurate mechanical properties of organs are required for better designing of surgical tools and virtual surgery environments. In this study porcine liver, kidney and spleen tissues are studied in vitro and hyper-elastic material laws are provided for each. 12 porcine kidneys are used to perform 40 elongation tests on renal capsule and 60 compression tests on renal cortex, 5 porcine livers are used to perform 45 static compression tests on liver parenchyma and 5 porcine spleens are used to carry out 20 compression tests. All the tests are carried out at a static speed of 0.05mm/s. A comparative analysis of all the results is done with the literature and though the results are of same order of magnitude, a slight dissonance is observed for the renal capsule. It is also observed that the spleen is the least stiff organ in the abdomen whereas the kidney is the stiffest. The results of this study would be essential to develop the FE models of liver, kidney and spleen which can be further used for impact biomechanical and biomedical applications.

High and abnormal forms of aggression in rats with extremes in trait anxiety – Involvement of the dopamine system in the nucleus accumbens

A better neurobiological understanding of high and abnormal aggression based on adequate animal models is essential for novel therapy and prevention. Selective breeding of rats for extremes in anxiety-related behavior resulted in two behavioral phenotypes with high and abnormal forms of aggression. Rats bred for low anxiety-related behavior (LAB) consistently show highest levels of aggression and little social investigation in the resident-intruder (RI) test, compared with non-selected low-aggressive (NAB) rats. High anxiety-related (HAB) rats also show higher levels of aggression than NAB rats, but to a lesser extent than LAB rats. Accordingly, extremes in inborn anxiety in both directions are linked to an increased aggression level. Further, both LAB and HAB, but not NAB males, display abnormal aggression (attacks towards vulnerable body parts, females or narcotized males), which is particularly prominent in LABs. Also, only in LAB rats, the nucleus accumbens (NAc) was found to be strongly activated in response to the RI test as reflected by increased c-fos and zif268 mRNA expression, and higher local dopamine release compared with NAB males, without differences in local dopamine receptor binding. Consequently, local pharmacological manipulation by infusion of an anesthetic (lidocaine, 20 μg/μl) or a dopamine D2 (haloperidol, 10 ng/μl), but not D1 (SCH-23390 10 ng/μl), receptor antagonist significantly reduced high aggression in LAB rats. Thus, LAB rats are an adequate model to study high and abnormal aggression. In LAB males, this is likely to be linked to hyper-activation of the reward system, as found in psychopathic patients. Specifically, activation of the accumbal dopamine system is likely to underlie the high aggression observed in LAB rats.

The neural background of hyper-emotional aggression induced by post-weaning social isolation

Post-weaning social isolation in rats is believed to model symptoms of early social neglect-induced externalizing problems including aggression-related problems. We showed earlier that rats reared in social isolation were hyper-aroused during aggressive contacts, delivered substantially more attacks that were poorly signaled and were preferentially aimed at vulnerable body parts of opponents (head, throat and belly). Here we studied the neural background of this type of aggression by assessing the expression of the activation marker c-Fos in 22 brain areas of male Wistar rats submitted to resident–intruder conflicts. Post-weaning social isolation readily produced the behavioral alterations noticed earlier. Social isolation significantly increased the activation of brain areas that are known to directly or indirectly control inter-male aggression. Particularly, the medial and lateral orbitofrontal cortices, anterior cingulate cortex, bed nucleus of the stria terminalis, medial and basolateral amygdala, hypothalamic attack area, hypothalamic paraventricular nucleus and locus coeruleus showed increased activations. This contrasts our earlier findings obtained in rats with experimentally induced hypoarousal, where abnormal attack patterns were associated with over-activated central amygdala, lateral hypothalamus, and ventrolateral periaqueductal gray that are believed to control predatory attacks. We have observed no similar activation patterns in rats socially isolated from weaning. In summary, these findings suggest that despite some phenotypic similarities, the neuronal background of hypo and hyperarousal-associated abnormal forms of aggression are markedly different. While the neuronal activation patterns induced by normal rivalry and hypoarousal-driven aggression are qualitative different, hyperarousal-associated aggression appears to be an exaggerated form of rivalry aggression.

Facial expressions of mice in aggressive and fearful contexts

Some animals display a variety of context dependent facial expressions. Previous studies have shown that rodents display a facial grimace while in pain. To determine if the facial expressions of mice extend beyond pain, facial expressions were analyzed in the presence of non-social, social and predator stimuli. In a vibrissae contact test, the whiskers of mice were stroked by the bristles of a brush. In a social proximity test, two mice were placed together in a small chamber where contact was virtually unavoidable. In a resident–intruder test of aggression, an unknown mouse was placed into the homecage of another mouse. In a cat odor exposure test and in a live rat exposure test, mice were presented with the respective stimuli. Results from this study indicated that mice showed two patterns of expression, either a full display of changes in the measured facial components, characterized by tightened eyes, flattened ears, nose swells and cheek swells; or a more limited display of these facial changes. The full display of changes occurred in the vibrissae contact test, the social proximity test, and in resident mice in the resident–intruder test. The more limited display of facial changes occurred in the cat odor exposure test, the rat exposure test and in intruder mice in the resident–intruder test. The differential display of facial changes across conditions indicated that mice showed tightened eyes and flattened ears in situations that provided the immediate potential for contact, suggesting that such changes are involved in protection of sensitive and/or vulnerable body parts. Furthermore, the display of facial expressions by mice indicates that these expressions are widely distributed across evolution.

Animal violence demystified.

Violence has been observed in humans and animals alike, indicating its evolutionary/biological significance. However, violence in animals has often been confounded with functional forms of aggressive behavior. Currently, violence in animals is identified primarily as either a quantitative behavior (an escalated, pathological and abnormal form of aggression characterized primarily by short attack latencies, and prolonged and frequent harm-oriented conflict behaviors) or a qualitative one (characterized by attack bites aimed at vulnerable parts of the opponent's body and context independent attacks regardless of the environment or the sex and type of the opponent). Identification of an operational definition for violence thus not only helps in understanding its potential differences from adaptive forms of aggression but also in the selection of appropriate animal models for both. We address this issue theoretically by drawing parallels from research on aggression and appeasement in humans and other animals. We also provide empirical evidences for violence in mice selected for high aggression by comparing our findings with other currently available potentially violent rodent models. The following violence-specific features namely (1) Display of low levels of pre-escalatory/ritualistic behaviors. (2) Immediate and escalated offense durations with low withdrawal rates despite the opponent's submissive supine and crouching/defeat postures. (3) Context independent indiscriminate attacks aimed at familiar/unfamiliar females, anaesthetized males and opponents and in neutral environments. (4) Orientation of attack-bites toward vulnerable body parts of the opponent resulting in severe wounding. (5) Low prefrontal serotonin (5-HT) levels upon repeated aggression. (6) Low basal heart rates and hyporesponsive hypothalamus–pituitary–adrenocortical (HPA) axis were identified uniquely in the short attack latency (SAL) mice suggesting a qualitative difference between violence and adaptive aggression in animals.

Early social deprivation induces disturbed social communication and violent aggression in adulthood.

Disturbed social relations during childhood (e.g., social neglect) often lead to aggression-related psychopathologies in adulthood. Social isolation also increased aggressiveness in laboratory animals. Here the authors show in rats, that social isolation from weaning not only increases the level of aggressiveness, but results in abnormal attack patterns and deficits in social communication. In socially deprived rats, the share of attacks aimed at vulnerable body parts of opponents (head, throat, and belly) dramatically increased and the attack/threat ratio was shifted toward attacks, suggesting a decrease in intention signaling. Moreover, a Multiple Regression Analysis showed that the nonassociation of attacks with offensive threats predicted the occurrence of vulnerable attacks with 81.1% accuracy. The authors suggest that the social deprivation-induced abnormal aggression models the aggression-related problems resulting from early social neglect in humans, and studies on its brain mechanisms may increase our understanding of the mechanisms underlying psychopathologies resulting from early social problems.

The Effect of Neurokinin1 Receptor Blockade on Territorial Aggression and in a Model of Violent Aggression

Neurokinin1 (NK1) receptor blockers were recently proposed for the treatment of anxiety and depression. Disparate data suggest that NK1 receptors are also involved in the control of aggressiveness, but their role is poorly known. We evaluated the aggression-induced activation of NK1 neurons by double-labeling brain sections for NK1 receptors and c-Fos in two laboratory models of aggression. We also studied the effects of the NK1 antagonist L-703,606 in these models. Aggressive encounters activated a large number of NK1 receptor-expressing neurons in areas relevant for aggression control. The activation was aggression-specific, because the effects of psychosocial encounters (that allowed sensory but not physical contacts) were markedly weaker. In the medial amygdala, the activation of neurons expressing NK1 receptors showed a marked positive correlation with the occurrence of violent attacks. In resident/intruder conflicts, NK1 blockade lowered the number of hard bites, without affecting milder forms of attack. In the model of violent aggression, attacks on vulnerable body parts of opponents (the main indicators of violence in this model) were decreased to the levels seen in control subjects. Autonomic deficits seen in the model of violent aggression were also ameliorated. The effects of the compound were not secondary to changes in locomotion or in the behavior of intruders. Our data show that neurons expressing NK1 receptors are involved in the control of aggressiveness, especially in the expression of violent attacks. This suggests that NK1 antagonists-beyond anxiety and depression-might also be useful in the treatment of aggressiveness and violence.

The effect of buspirone on normal and hypoarousal-driven abnormal aggression in rats

Aggressiveness is associated with decreased glucocorticoid production, autonomic hypoarousal, and social deficits in antisocial personality disorder and its childhood antecedent conduct disorder. We showed previously that experimentally induced chronic glucocorticoid deficiency leads to abnormal forms of attack, autonomic hypoarousal, and social deficits in rats. We also showed that serotonergic neurotransmission, which downregulates aggressiveness in normal rats appears to lose its aggression-controlling role in glucocorticoid-deficient rats. We suggested that abnormal aggression develops in such rats as a consequence of serotonergic disturbances that result from chronic glucocorticoid deficiency. Here we assessed the effects of the serotonergic anxiolytic buspirone on aggressive behavior in normal and glucocorticoid-deficient rats. Noteworthy, this compound is frequently used in the clinic to control moderate aggression problems. As expected, buspirone dose-dependently reduced the duration of agonistic behaviors in normal rats exposed to resident/intruder conflicts. Similar to earlier experiments, glucocorticoid deficiency dramatically increased the share of attacks directed towards vulnerable body parts of the opponents (head, throat and belly). Surprisingly, 1 and 5 mg/kg buspirone dramatically increased the frequency of biting attacks in glucocorticoid-deficient rats. The share of vulnerable attacks remained as high as in vehicle-treated glucocorticoid-deficient rats. These data show that chronic glucocorticoid deficiency disturbs serotonergic neurotransmission, which reverses the aggression-related effects of the serotonergic agent buspirone. This finding is in line with disparate human findings on the effects of serotonergic agents on aggression in antisocial personality disordered people.

Influence of Personal Armor on Distribution of Entry Wounds: Lessons Learned from Urban-Setting Warfare Fatalities

This study was undertaken to examine the distribution of entry wounds resulting from firearms and shrapnel in soldiers wearing military personal armor systems (MPAS) in low-intensity urban combat conditions. Data were collected for a retrospective analysis on all combat fatalities sustained by the Israeli Defense Force (IDF) between March 30, 2002, and April 22, 2002, during Defensive Shield Operation in the West Bank. Twenty-six of the 30 fatalities were evaluated in the Israeli National Center of Forensic Medicine. A total of 149 entrance wounds were divided into shrapnel and bullet groups. The "face-neck" region had the highest density rate compared with other body regions in both shrapnel and bullet groups (2.97 and 2.41, respectively; p < 0.0001). In both groups, the overall prevalence of anterior injuries was significantly higher than posterior ones (78.9% vs. 21.1% in the shrapnel group and 68.5% vs. 31.5% in the bullet group, p < 0.001). However, anterior and posterior chest injuries had a reverse yet more even distribution (43.8% and 56.2% in the bullet group and 40% and 60% in the shrapnel group, respectively; p < 0.001). The difference in the average diameters of entry wounds in the covered versus uncovered regions (0.79 +/- 0.42 cm vs. 0.73 +/- 0.29 cm, respectively) was not statistically significant (p = 0.11). The use of MPAS turned the face-neck region into the most vulnerable body part, as shown by its prominent density rate, especially in the shrapnel group. MPAS designed for urban setting warfare should provide maximal shielding both to the anterior and posterior chest regions. The diameter of entrance wounds in the covered versus the uncovered areas was not statistically significant, suggesting that only a minor deformation of the bullet takes place while traversing the Kevlar vest.

Touch Among Children at Nursery School

Naturalistic observations of touching behaviors were conducted among 33 preschool children, ranging from 3 to 64 months of age. Touch was coded for direction (received/initiated), type, body area touched, responses to touch, and purpose. Infants received significantly more touch than older children. Preschool children engaged in touching behaviors similar to those observed among adults. Touch involved “vulnerable body parts” more often among toddlers than among preschoolers. ‘Negative’ responses to being touched occurred more often among toddlers than among preschoolers, and task‐related touch occurred less often in the preschool than in the toddler and infant classes.