Title & Introduction
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Offense, Defense & Patrol/Marking
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Neural Circuitry & Motivational Mechanisms
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How Circulating Hormones May Affect Behavior
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Pregnancy and Lactation
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ACTH, etc.
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Reproductive States
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Conclusion
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References
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OFFENSE VERSUS DEFENSE
The offense motivational system may be distinguished from the defense motivational system on both neural and behavioral grounds in muroid rodents. Lesions of the medial and lateral hypothalamus affect them differentially; medial hypothalamic lesions enhance defense and do not affect offense, while lateral hypothalamic lesions abolish offense and do not affect defense (Adams, 1971). Behavioral studies have shown that offense includes a "bite-and-kick" attack directed at the back or flank of the opponent after assumption of a stereotyped full aggressive posture, while defense is characterized by a "lunge-and-bite" attack directed at the face or other protruding part of the opponent and launched from a position some distance from the opponent with the forepaws extended to push the attacker back from the target as soon as the bite is delivered. The offensive bite-and-kick attack is used by a resident animal, while the defensive lunge-and-bite attack is used by an intruder (Adams, 1976; Blanchard, Fukunaga, Blanchard, & Kelley, 1975; Lehman & Adams, 1977). As a result, intruders are bitten on the back and flank, while residents are bitten on the face (as has been observed in Microtus agrestis: Clarke, 1956; Dicrostonyx groentandicus:Bowen & Brooks, 1978; Microtus ochrogaster: Rose & Gaines, 1976; and Rattus norvegicus: Blanchard et at., 1975; Calhoun, 1962, p. 181; Crabtree & Moyer, 1973; Thor, 1976). There are many other differences between offense and defense, such as different displays associated with the two (Grant & Mackintosh, 1963; Johst, 1967).
Maternal aggression appears to be the simultaneous activation of both offense and defense. No studies have yet been done to determine the neural substrate of maternal aggression, but the presence of both bite-and-kick attack and lunge-and-bite attack in the enhanced aggressiveness of the lactating female suggests that both offense and defense are involved (Adams, 1980).
DEFENSE VERSUS SUBMISSION
Whereas the distinction between offense and defense is now agreed on by many researchers of the brain mechanisms of aggression, the distinction between submission and defense is more controversial (cf. commentaries in Adams, 1979a, especially those of Blanchard and Blanchard). As evidence for the distinction, I have pointed to the fact that muroid rodents are much more likely to engage in a lunge-and-bite attack after lesions of the septum and ventromedial hypothalamus. Usually, the lunge-and-bite attack is used during intraspecific fighting by wild animals and not by laboratory animals; in fact, the behavior of animals with septal and ventromedial hypothalamic lesions is similar to the normal defense behavior of wild animals. Not only the lunge-and-bite attack but also various other motor patterns of defense are more vigorous in laboratory animals after these particular lesions and are more similar to the defense of wild animals.
To explain the effects of lesions and the differences between wild and laboratory animals, I have postulated that there are two related but alternative motivational mechanisms, submission and defense, that are under the control of a consociate modulator {Adams, 1979a,b). The motor patterns activated by the two motivational mechanisms are similar in most respects, although defense includes the lunge-and-bite attack, while submission includes ultrasound and specific submissive postures. Since both defense and submission can be abolished by lesions of the midbrain central gray and adjoining tegmentum (Edwards & Adams, 1974), I have suggested that this is the location of the two motivational mechanisms. The consociate modulator is responsible for shifting the animal's "fear-induced" behavior from defense to submission when the opponent is a familiar animal-a consociate. The consociate modulator may be located in the ventromedial hypothalamus, from which it inhibits defense and facilitates submission.
PATROL/MARKING
There are a number of behaviors involving locomotion and scent-marking that are functionally related to physical conflict between adult members of the same species and that should be included within the definition of agonistic behavior in muroid rodents. These behaviors have been variously described as "patrol" (Crowcroft, 1955; Mackintosh, 1970), "passage-guarding" (Anderson & Hill, 1965; Calhoun, 1962), and "sentry" (Crowcroft, 1955). From these behavioral descriptions it would appear that dominant, territorial animals appear to seek out confrontations with intruders into their territory. Along with scent-marking behaviors, that are also functionally related, I have included these behaviors in a motivational system called patrol/marking (Adams, 1980).
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