Brain Research, 63 (1973) 111-121 111 © ElsevierScientific PublishingCompany,Amsterdam - Printed in The Netherlands SIMULTANEOUS STIMULATION OF THE SUBCORTICAL SYSTEMS GOVERNING AGONISTIC BEHAVIOUR G. SIERRA, C. ACUlqA*, J. OTERO* AND A. GUILLAMON* Laboratory of Neurophysiology, Department of Physiology, School of Medicine, Santiago de Compos- tela (Spain) (Accepted April 22nd, 1973) SUMMARY Development of rat-killer behaviour by environmental factors was observed in two cats. Food deprivation, however, never converted a non-killer into a killer cat. Stimulation of certain points in the basolateral region of the amygdala arrests the spontaneous rat-killer behaviour, but does not prevent the attack which is induced by electrical stimulation of hypothalamus or central gray matter. On the other hand, the stimulation of hypothalamus and/or central gray matter may overcome the in- hibitory effects of the electrical stimulation of the amygdala. INTRODUCTION Agonistic behaviour can be evoked by direct electrical stimulation of the brain, as demonstrated in the hypothalamus by Hess 10 and in the central gray matter by Hunsperger la. The experimentally initiated attack showed a display much like that of a normal animal 11-1a. These experimental findings have been confirmed subsequently by numerous investigators (for reviews see refs. 2, 8, 14, 16). The meaning of this experimentally induced attack has been questioned by Masserman la on the grounds that rage reactions induced by hypothalamic stimulation differ significantly from the true emotional states. Milled 9 was unable to condition the centrally aroused rage. On the other hand some experimental data suggest that the attack induced by stimulation of the central gray matter of the brain stem may be secondary to feeling pain ~5. However, there is evidence of conditioning using hypo- thalamically induced flight or defence responses as the unconditioned stimuli20. * Fellows of the Programme 'Formaci6n de Personal Investigadordel Ministerio de Educaci6n y Ciencia', Spain.