Electrostimulation of the hypothalamus as a signal of food or electrocutaneous stimulation.

Instrumental conditioned reflexes (CRs) were elaborated in dogs. In the first and second series of experiments-alimentary reflexes, in the third-defensive ones. Conditioned stimuli were light flashes in the first series and electrostimulations (ESs) of the lateral hypothalamus (LH) in the second and third series. During the formation and stabilization of CRs. ESs of other structures of the limbic system (LS) induced instrumental reactions. In the first series they were less perfect, arising in response to stimulation of a small number of LS structures and more seldomly, than in the second and third series. Statistically significant differences were found between data of the first and second series in per cent of instrumental movements, for a major part of LS structures. But no difference were found between the second and the third series. These facts confirm the suggestion that the phenomenon, revealed in the second and third series, is based mainly on the mechanism of afferent generalization. A change of the motivational level by electrostimulation of limbic structures probably activated environmental reflexes and intensified the generation of CR. However, weakly manifested instrumental reactions to ES of LS structures in the first series and insignificant differences between data of the second and third series serve as evidence about the minor participation of the second mechanism in this phenomenon.