Studies in the neurophysiology of learning: IX. Conditioning of evoked potentials due to cerebral stimulation

The hypothesis to be tested was that if characteristic undulatory evoked potentials could be produced by electrical stimulation of the lateral hypothalamus, sensory stimuli originally neutral should evoke such potentials, if only of smaller amplitude. The results of experiments on four albino rats are reported. Stimulation of the lateral hypothalamus by electrical current at 200 biphasic rectangular pulses per second results in 7-12 cycles-per-second undulations persisting for about .5 second and derivable from several regions of the cerbrum. By means of the Pavlovian paradigm, it was possible to condition these to an auditory and to a visual stimulus. The conditioned undulations had smaller amplitudes, did not persist as long to CS as to US, and were characterized by considerable lability. From 100 to 300 CS-US pairings were required.