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1. Defense and the Conditional Reflex
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2. Flight, Locomotion and Image Memory
Page 2

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3. Olfactory Familiarity and Imprinting
Page 3

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Neophobia and Object Memory
Page 4

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Learning of "Wildness"
Page 5

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Habituation to Handling
Page 6

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Learning of Visually-Released Boxing
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Conclusion
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Figure 1
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Bibliography
Page 10

It is well known that fear and fear-motivated behaviors may be conditioned to previously neutral stimuli. In terms of the schema presented here, the defense motivational mechanism may be activated by conditional stimuli. Although Pavlov was always concerned with this problem, he did not usually investigate the defense behaviors of one animal in direct response to a predator or second attacking animal, and in a recent review, Simonov [57] points out that the method of conditional reflexes has been used to a small degree in the analysis of social behavior. Following defeat by an opponent, rats and mice show defensive behaviors to stimuli associated with the opponent [27, 55, 53, 37] although the phenomenon has not usually been investigated in detail.

There is one detailed study of the role of the conditional reflex in the upright posture and boxing response of paired rats given footshock in a small enclosure. Vernon and Ulrich [63] found that the responses could be conditioned to auditory stimuli associated with the footshock. Controls for pseudoconditioning were successful; there was no conditioning when the tone was presented after instead of preceding shock. Such conditional reflexes are probably responsible for the fact that shock elicited upright posture and boxing tends to increase in frequency over repeated test sessions [20].

Where is the site of action of the conditioning in this case? The following evidence suggests that it is in the midbrain central gray. I have suggested in previous studies that the midbrain central gray contains the neurons which constitute the defense motivational mechanism [22, 45]. Since the conditional stimuli may be elaborated in association with a variety of unconditional motivating stimuli of defense, including noise, movement, pain, dorsal tactile sensation, and restraint, it may be hypothesized that the effect takes place at that site in the brain where all of these motivating inputs converge upon the defense motivational mechanism, i. e., the midbrain central gray. In support of this hypothesis is the finding that cells in the midbrain central gray which respond maximally during defense, also respond at lower rates to stimuli associated with the presentation of the attacking opponent, e. g., the opening of the partition which separates the two animals [1, 45].