[Localization of thalamic afferents in the regio cingularis of the rat]

After lesioning the nucleus mediodorsalis and the nucleus anteromedialis thalami, where from specific afferents project to the cingulate cortex, we confirm signs of transneuronal degeneratiopn at lamina-V-pyramidal neurons of the cingulate cortex. By the GOLGI-KOPSCH-method operated animals show statistically significant decrease of dendritic spines at the apical main dendrites of lamina-V-pyramidal cells compared with the controls. The average spine-decrease along 300 micrometer length of the apical main dendrite amounts to 16%. Maximal spine-decrease is present at the central part of the apical main dendrite: 23% within a 50-micrometer-segment of this dendrite. This central dendritic part passes through the lamina III of the cingulate cortex. By the FINK-HEIMER-method degeneration particles are preferentially dispersed in laminae I, III and lower layers. The results give evidence for a more precise neuronal localization of the specific afferent terminations in this region.