Self-stimulation of the lateral hypothalamus and ventrolateral tegmentum: excitability characteristics of the directly stimulated substrates.
Recovery from refractoriness in the neural substrate for self-stimulation of the ventrolateral tegmentum (VLT) was estimated using psychophysical techniques, and compared to recovery in the substrate for self-stimulation of the lateral hypothalamus (LH). A computer-controlled testing setup was developed to minimize experimenter error and testing time. In order to assess the performance of this setup, refractory period estimates obtained in the newly designed, computer-controlled equipment were compared to those obtained in the hand-operated equipment used in previous experiments of this type. No meaningful differences were found. Thus, the more convenient computer-controlled setup was used to collect refractory period estimates from the VLT and LH. A comparison of these values revealed differences in the slopes of the recovery curves, and in the C-T intervals bracketing their rising portions. The VLT curves rose more gradually, and both began to rise and levelled off at longer C-T intervals than the LH curves. One explanation of these results is that the distribution of excitability in the LH substrate is shifted towards higher values than the VLT distribution. The overlapping portions of the recovery curves could reflect the contribution of a common bundle of reward-related fibers.
D000818:Animals; D001931:Brain Mapping; D004298:Dopamine / Q000502:physiology; D007026:Hypothalamic Area, Lateral / Q000502:physiology*; D008297:Male; D008474:Medial Forebrain Bundle / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology*; D051381:Rats; D012032:Refractory Period, Electrophysiological; D012653:Self Stimulation / Q000502:physiology*; D009435:Synaptic Transmission; D013681:Tegmentum Mesencephali / Q000502:physiology*
D004298:Dopamine