Unique releasing stimulus analyzers project to each motor patterning mechanism. In preliminary work with Jaap Koolhaas in the Netherlands, I have found that these releasing stimuli can be defined by appropriate sensory deprivation experiments. Approach locomotion requires visual and auditory releasing stimuli and is abolished if the animal's ears are blocked and it is tested in total darkness. The offensive upright posture and the full aggressive posture are released primarily by the facial tactile hairs, particularly the vibrissae. The offensive sideways posture and the bite-and-kick attack survive total sensory deprivation of the visual, auditory, and facial tactile systems, suggesting that they are mediated by tactile sensations from the lateral and ventral surfaces of the body, respectively. It should be noted that under the abnormal conditions of total sensory deprivation, it is possible to obtain motor patterns without appropriate releasing stimulus inputs, as will be discussed below.

Two analyzers of motivating stimuli for offense are shown: one tuned to male odors and the other tuned to unfamiliar conspecific odors. The argument that these are the two principal sets of motivating stimuli which activate the motivational mechanism of offense has been made previously in detail (Adams, 1980). A recent experiment (Mink and Adams, 1981) suggests that the sensory analyzer for unfamiliar conspecific odors does not require a comparison to environ- mental odors, which obviates the need for a special "olfactory comparator mechanism" that was suggested in an earlier paper (Adams, 1979b). There are several inhibiting motivational stimuli, but they are not shown in this figure in order to conserve space.

Androgens and estrogens affect the offense motivational system at two points. Androgens organize and activate the motivating stimulus analyzer that is sensitive to male odors; as a result it is males that attack other males through this mechanism. Estrogens inhibit offense when they are at high levels (estrus), which explains why estrous females normally do not engage in offense. At the same time, however, estrogens facilitate the input from hunger to offense, which explains why females often have higher levels of competitive fighting than males, and why competitive fighting persists during estrus (Adams, in press).

"Reverse" connections from the motivational mechanism to the various sensory analyzers of the offense motivational system is illustrated in the figure. Such connections have been postulated earlier (Adams, 1979a) on the basis of reverse connections from the motivational centers of predatory behavior to the various releasing stimulus analyzers of that behavior in the cat (Flynn et al, 1971). They are shown here for the first time in detail, however.

Another type of "reverse connection," a negative feedback from the bite-and-kick motor patterning mechanism to the offense motivational mechanism is illustrated. This was postulated in a recent paper (Mink and Adams, 1981) to explain why offense motivation appears to decrease for several minutes immediately following a bite-and-kick attack, at least under some conditions.

In contrast to the other motor patterns of offense, the bite-and-kick attack appears to have a higher threshold, as has been illustrated in the figure, and as we have previously suggested (Mink and Adams, 1981).