[Anatomical study of the afferent pathways of the rostral telencephalon in the Gallus domesticus chick].

The neuroanatomical method involving retrograde axonal transport of horseradish peroxidase (HRP) was employed in the chick Gallus domesticus to investigate ascending projection systems to the rostral telencephalon. Following either extensive or restricted injections of the enzyme into different regions of the latter, differential bilateral or unilateral projections onto the Wulst (hyperstriatum accessorium, hyperstriatum intercalatus superior, hyperstriatum dorsale) were demonstrated from the dorsal thalami complex (nucleus dorsolateralis anterior thalami, pars lateralis). Other nuclei of the dorsal thalamus shown to project to the rostral telencephalon were nuclei, dorsolateralis medialis, dorsolateralis posterior, dorsomedialis anterior, parvocellularis and rotundus. At the level of the mesencephalon, rostral telencephalic projections were found to originate in the substantia grisea centralis, the strata cellulare externum and internum, the lateral reticular formation and the area ventralis. More caudally peroxidase label was localized in the nuclei locus, ceruleus, subceruleus dorsale, subceruleus ventrale and within the principal Vth nucleus. The results obtained using restricted injections of HRP made it possible to more precisely identify the telencephalic projections sites of several of the above areas and nuclei. The data is compared to previous findings regarding ascending projection system in different avian species and some methodological problems in the use of HRP technique are discussed.