[Effect of excitation summation during interaction of self-stimulation zones]

A study was made on rats with electrodes implanted in the lateral preoptic hypothalamic area, of the interaction between distant foci of "positive" excitation in a situation when one of the foci (conditioning one) was set up by the animal itself by self-stimulation with a rhythmic current, while the other (testing) was imposed through stimulation of a different positive point with rhythmic and direct currents. Imposed stimulation of the distant positive zones by rhythmic current within a sufficiently wide range of intensities intensifies the self-stimulation in the conditioning focus. Polarization of the testing positive zones by a DC cathode produces a two-phase reaction of the conditioning points of self-stimulation: initial inhibition at the action of relatively weak DC intensities attended with its subsequent intensification when intensity of the polarizing current increases. It is suggested that the motivation (low-threshold) and reinforcing (high-threshold) components may be involved in the mechanism of phasic interaction between excitation foci in the self-stimulation system.