Connections of vocal control nuclei in the canary telencephalon

TLDR

In adult canaries, the hyperstriatum ventrale, pars caudale (HVc) receives ipsilateral projections from the medial nucleus magnocellularis of the anterior neostriatum (MAN), nucleus interfacialis (NIf), and nucleus uvaeformis (Uva), while HVc projects to area X, the robust nucleus of the archistriatum (RA), and field Avalanche, and RA receives inputs from HVc and lateral MAN. The study investigated the connections of the HVc and RA nuclei in adult canaries. Transport of horseradish peroxidase and 3 H‑adenosine, together with silver staining of degenerating axons, was used to map these connections. The findings revealed that NIf and Uva nuclei were previously unreported, showed no sex differences in HVc connectivity, and that HRP uptake indicates HVc consists of rostrocaudally organized clusters with limited lateral communication.

Abstract

Abstract Connections of two telencephalic vocal control nuclei, the hyperstriatum ventrale, pars caudale (HVc), and robust nucleus of the archistriatum (RA), were investigated in adult canaries. Methods used were transport of horseradish peroxidase and 3 H‐adenosine and silver staining of degenerating axons. Three nuclei project to HVc: medial nucleus magnocellularis ofthe anterior neostriatum (MAN), nucleus interfacialis (NIf) of midneostriatum, and nucleus uvaeformis (Uva) of the diecephalon. Uva also projects to NIf. NIf and Uva have not been described previously. HVc projects to area X of lobus parolfactorius, to RA, and to field Avalanche of hyperstriatum ventrale. Nucleus RA receives projections from HVc and from lateral MAN. All these projections are ipsilateral. No gross male/female differences were apparent in the projections to and from HVc. Uptake of HRP by cell somata in HVc following localized injections of this substance into RA or HVc suggests that HVc is composed of rostrocaudally organized clusters of cells, with little lateral communication between them.