An experimental study of the relation between the medial mamillary nucleus and the cingulate cortex

Abstract

The cellular changes in the mamillary nuclei following lesions of the cingulate cortex, the anterior thalamic radiation and the anterior thalamic nuclei have been studied in rabbits varying in age from 10 days to young adults. Distinct cellular degeneration ranging in severity from slight cell shrinkage to complete cell loss occurs in the medial and supra-mamillary nuclei subsequent to the retrograde changes in the anterior thalamic nuclei. The severity of this 'retrograde transneuronal degeneration' is a function of the age of the animal at the time of operation and of the post-operative survival period. With the aid of this technique, it has been shown that the caudal part of the pars anterior and the ventro-lateral two-thirds of the pars medialis of the medial mamillary nucleus project to the antero-medial nucleus of the thalamus, the pars basalis to the antero-dorsal nucleus and the pars posterior to the antero-ventral nucleus. No changes were observed in the lateral mamillary nucleus in any of the experiments.