[Disturbances of the human instinct behaviour in hypothalamic lesions (author's transl)]

Since the findings of W.R. Hess, who systematically stimulated the hypothalamus of the cat, motivational systems for instinct behaviour have been postulated in the hypothalamus and the surrounding limbic brain. It has been asked, if hypothalamic lesions in man would cause alterations in instinct behaviour, which could be attributed to the instinct motivational systems. Therefore 19 patients with hypothalamic lesions have been examined in respect of their instinct behaviour. They showed no qualitative alteration in their instinct behaviour, but quantitative diminution and rarefication of their gain instincts (nutritional, sexual and social instinct). Mainly reduced was the sex instinct together with hormonal deficiency. Inversely the safety instinct (the only avoidance instinct with variable threshold) was more often activated. The other avoidance instincts (for excretion, thermo-regulation, bodycare and painavoidance) remained intact. It is concluded that the pacemaker for the threshold of the gain instincts and of the safety instinct is disturbed and not the motivation system in its qualitative functioning. As this pacemaker is so characteristically different in each instinct, the theory of different specific motivational systems is more probable than the theory of one unspecific system with different functions.