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Introduction
Page 1
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Results
Pages 5 - 6 - 7 - 8 - 9
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Discussion
Pages 10 - 11
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References
Page 12
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Added figures
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Figures
Figures 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10
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The purpose of this study was to search for cells in the brain of the cat which might mediate affective defense behavior. It was assumed that such cells would discharge only during affective defense behavior or, at least, at a greater rate during affective defense than during any other behavior. Therefore, the experiment was designed to explore areas of the brain and record extracellularly from single cells while the cat was displaying affective defense, while it was subjected to control manipulations, and while it was resting quietly.
Affective defense, as described by Hess and Brugger (6), may be obtained by electrical stimulation of certain areas of the midbrain, hypothalamus, and amygdala of the unanesthetized cat, and is similar to the reaction one sees from a cat defending itself against an attacking animal. It may include growling, hissing, piloerection, pupil dilatation, ear retraction, arching of the back, and striking with unsheathed claws. In previous studies, affective defense has often been elicited by relatively unphysiological means, including brain stimulation, lesions of the ventromedial hypothalamus, touch or restraint of decorticate or thalamic preparations, and stimulation of peripheral nerves. In the present study the behavior was elicited as naturally as possible by confronting the cat with a second attacking cat.
In order to maintain recording from single cells while the cat was fighting, it was necessary to develop a special electrode and drive system, which was particularly stable with respect to the brain case and which could serve to anchor the tissue around a cell and keep it from shifting when the cat moved suddenly.
Two areas of the brain where affective defense may be obtained by electrical stimulation were explored: the hypothalamus in and around the ventromedial nucleus and fornix; and the midbrain in and around the central gray. Following the recording from a cell, the area around that cell was electrically stimulated through the same electrode. It was hoped that a correlation could be found between the results of these two procedures: that in areas where it was possible to record electrical activity evoked specifically during naturally elicited affective defense, it might also be possible to produce affective defense behavior by electrical stimulation. It was also hoped that the area implicated in affective defense by the recording technique might be more anatomically distinct than that implicated by stimulation. Stimulation can produce affective defense over rather extensive regions of the midbrain and hypothalamus but the extent may be due to current spread.
A preliminary report on some of this work has already been published (1).
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