A genetically mediated relationship between the readiness to self stimulate lateral hypothalamus and the intensity of the septal and ventromedial hypothalamic rage syndromes.

Rats from two genetically high self stimulating lines (LC1-Hi, LC2-Hi) and from two genetically low self stimulating lines (LC1-Lo, LC2-Lo) were subjected to septal lesions at various ages. The genetically high self-stimulators exhibited the typical marked increase in emotionality following septal lesions, while the genetically low self stimulators showed an attentuated emotional response following septal lesions. In a subsequent experiment, animals from the same lines were subjected to VMH lesions. Once again, animals from the genetic high self stimulating lines showed a marked increase in emotionality following the lesions while the animals from the genetic low self-stimulating lines showed an attenuated emotional response. Hyperphagia was observed in all lines with no relation to the self stimulation genetic background. It is suggested that the septal and VMH systems modulating affective behavior are functionally related to the system modulating self stimulation, while these mechanisms seem to be basically independent of the VMH systems involved in maintenance of body weight.