Specificity of auditory evoked potentials from rat hypothalamus: differential recording by lateral and ventromedial electrodes

Evoked potentials recorded from ventromedial nucleus (VMH) and lateral area (LHA) of the hypothalamus were studied in freely moving rats with respect to specificity of the components to recorded areas and to peripheral stimuli utilized. This study attempts to circumvent some methodological problems and contamination in data with respect to origin of recorded components by comparing monopolar and differential recordings made in VMH and LHA, areas accepted as being involved in food-intake behavior. Of the stable components, the complex with 15-20 ms latency was evaluated as of extra-hypothalamic origin. Meanwhile, those with 25-ms (positive) and 40-ms (negative) average peak latencies were considered as specific to recorded areas. Hypothalamic responses appeared not to be specific to stimulus modality, indicating convergence of different sensory modalities on studied areas. Hunger and satiety appeared to influence the amplitude of the specified components similarly, the study not providing evidence for the reciprocal relation stated in the dual center hypothesis between VMH and LHA.