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.
Page 8
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Reproductive States
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Conclusion
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References
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NEURAL CIRCUITRY OF AGONISTIC BEHAVIOR
The neural circuitry of agonistic behaviors may be considered as the substrate on which circulating hormones influence these behaviors. From this it follows that the more we know of this circuitry, the better we will understand how hormones affect agonistic behavior.
The analysis of the neural circuitry of agonistic behavior is still hypothetical and rather general. The analysis of the circuitry at the level of recording from individual neurons has been attempted in only a few studies (Adams, 1968; Mink, Adams, & Sinnamon, in press; Pond, Sinnamon, & Adams, 1977; Sandner , Schmitt, & Karli, 1979). Our knowledge, instead, is still limited to data from lesion and electrical-stimulation techniques that tell us which gross brain areas are involved, such as the amygdala, septum, midbrain central gray, etc. At this level the picture is complicated, because it appears that the various motivational systems of agonistic behavior involve neural substrates with substantial overlap in these regions. Offense, defense, and submission all involve forebrain pathways that process motivating stimuli in the septum, basal forebrain, and amygdala; convey these influences to the hypothalamus; and then relay them caudally to motivational mechanisms in the midbrain (Adams, 1979a). Patrol/marking may also involve similar overlapping pathways.
MOTIVATING STIMULI AND MOTIVATIONAL MECHANISMS
The neural circuitry of agonistic behavior may be analyzed in terms of different components of their motivational system. I have distinguished four such components (Adams, 1979a; Adams, 1980). Central to a motivational system is a set of homogenous neurons (still only hypothetical since the neuronal basis of behavior is not well known) that I have called a motivational mechanism. Activity of these neurons determines the motivational state of the animal, for example, whether it is offensive, defensive or submissive at that particular moment. The actual motor patterns that the animal performs are primed by the firing of inputs from the motivational mechanism to the neural substrate of the motor pattern, which I have called the motor-patterning mechanism. Whether or not a motor pattern is produced, however depends on simultaneously active inputs from releasing and directing stimuli as well.
Sensory influences on motivational systems may be distinguished in terms of the level on which they act on their neural circuitry. If sensory influences act on the motivational mechanism, then they may be considered motivating stimuli. These stimuli affect all of the motor patterns of the motivational system equally. Thus, for example, the motivating stimulus of pain for the defense motivational system activates not only a lunge-and-bite attack but also the defensive sideways posture, defensive upright posture, flight locomotion, freezing, etc. If, on the other hand, sensory influences act on individual motor patterns and not on related motor patterns, then they may be considered releasing and directing stimuli. Such stimuli release and direct individual motor patterns. Thus, for example, vibrissal inputs function as releasing and directing stimuli of the defensive upright posture (Kanki & Adams, 1978), but they do not appear to be motivating stimuli that can activate other motor patterns of defense such as squealing, freezing, etc.
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