Brain mechanisms for offense, defense, and submission

The inhibitory modulation of agonistic behavior in the rat brain: a review

Neural regions which exercise an inhibitory influence on agonistic behavior are identified by the enhancement of agonistic behavior that follows their removal. The specific kinds of agonistic behaviors altered by each region are then examined. Increased reactivity to the experimenter and enhanced shock-induced fighting are produced by lesions of the region ventral to the anterior septum, the lateral septum, the medial hypothalamus, and the dorsal and median raphe nuclei. It is argued that the increased reactivity and shock-induced fighting correspond to an enhancement of defensive behavior. Mouse killing is induced by lesions of the anterior olfactory nucleus, the region ventral to the anterior septum, the lateral septum, the medial hypothalamus, the dorsal and median raphe nuclei, and the medial amygdala. Because the lesion-induced mouse killing is similar to that emitted by spontaneous mouse killers, it is argued that these regions normally exert an inhibitory control over predatory killing. The available evidence on social attack behavior has not convincingly identified regions exerting an inhibitory control over this dimension of behavior. Our conclusion is that separate brain systems exert an inhibitory control over defensive behavior, predatory killing, and social attack behavior. To a substantial extent, the regions modulating these behaviors appear to act independently of one another. The only neurotransmitter that is clearly active in these inhibitory systems is serotonin, and has only been directly implicated in the control of mouse killing by neurons originating in the dorsal and median raphe nuclei.

Immediate behavioral effects of kainic acid injections into the midbrain reticular core

Microinjections of kainic acid into the midbrain reticular core were performed in chronically implanted, unanesthetized cats. The immediate effects of kainate excitation were studied during the first 8 h, in animals without any behavioral or EEG signs of epilepsy. Animals displayed pupillary dilatation, piloerection, accelerated respiration, a frozen attitude with a complete lack of facial expression, and no or only very slight orienting reactions. The most structural syndrome was a hallucinatory-type behavior that began in the first hour following the injection. Animals moved forward in a crouched position as if stalking a prey, vocalizing and opening their mouth in an attacking attitude, or moved back as if defending themselves against as imaginary menacer, seeming virtually terrified. The EEG desynchronization began 20-30 sec after the onset of injection and lasted for 12-14 h without any trace of alpha rhythm, spindles or slow waves. Control injections of buffer solution into the midbrain core and kainic acid in other cerebral structures were followed neither by the hallucinatory defense-attack syndrome, nor by comparably long-lasting EEG desynchronization. The hallucinatory-type behavior elicited during the waking state in the present experiments is compared to the oneiric behavior described by Jouvet and Delorme [21] during paradoxical sleep in animals with suppression of muscular atonia, and possible common mechanisms are discussed.

Selective anti-aggressive properties of DU 27725: ethological analyses of intermale and territorial aggression in the male rat

The effects of a new anti-aggressive compound, DU 27725, were evaluated in intermale and territorial aggression. Ethological analysis of intermale aggression showed that DU 27725 (1 to 8 mg/kg IP) strongly decreased aggression, while introductory social behaviour was unaffected or enhanced. The offensive character of aggression disappeared and was replaced by a more defensive pattern. No drastic changes occurred in non-social activities. Sedation, muscle relaxation and motor impairment did not occur at any of the doses tested, suggesting that the anti-aggressive effects were not caused by nonspecific actions of the drug. In territorial aggression, DU 27725 (4 and 8 mg/kg IP) also decreased all aspects of aggression; introductory social behaviour was slightly decreased, and defensive behaviour remained unaffected. At the highest dose (8 mg/kg) sedation was observed. DU 27725 reduced both the number of ultrasonic vocalizations and the number of bites inflicted upon the partners.