Alterations in feeding and drinking behavior of rats with lesions in globi pallidi

Abstract

Stereotaxic lesions were placed in several parasagittal planes of the lateral hypothalamus of rats at the level of the ventromedial nuclei. Both far- and mid-laterally lesioned animals developed adipsia and aphagia, with the far-lateral syndrome being more drastic in nature. The qualitatively different nature of the "failures" seen between the two groups correlated well with the additional damage to the pallidofugal fiber systems in the far-lateral lesioned group. Bilateral lesions directed to the origins of the pallidofugal fibers reproduced faithfully the far-lateral hypothalamic syndrome, histological studies in these animals revealing degeneration along the pallidofugal trajectories. It appears that the feeding and/or drinking "centers" are only convergence sites for critical fiber systems which are disjoined by far-lateral hypothalamic lesions. Thus, the medial part of the "feeding center" seems to be primarily a "motivational" system, whereas the lateral "feeding" system is more basic and depends essentially on pallidofugal circuitry. When this latter is disjoined, the failure is more than "motivational," since it is not compensated for by merely delivering food and water to the gastrointestinal tract.