Projections of a telencephalic auditory nucleus– field L–in the canary

Abstract

Anterograde projections of a telencephalic auditory area – field L of the neostriatum – were traced in canaries, Serinus canarius. Field L was defined as the neostriatal projection of nucleus ovoidalis of the thalamus. Using amino acid autoradiography, two efferent projections of field L and adjacent neostriatum were observed: (1) a projection to the medial and ventral borders of nucleus hyperstriatum ventrale, pars caudale (HVc) and (2) a smaller projection to medial paleostriatum augmentatu (PA). When autoradiographic injection sites included neostriatum postero-ventral to field L, a projection to archistriatum outlining the anterior and ventral borders of the nucleus robustus archistriatalis (RA) resulted. Injection sites that included neostriatum antero-lateral to “L” gave rise to projections to the interior of HVc proper. Above background numbers of silver grains were consistently observed over caudal dorso-lateral portions of nucleus ovoidalis. Following lesion of field L and adjacent neostriatum, argyrophilic degeneration was traced to medial PA and to a shelf of neostriatum underlying HVc. All observed anterograde projections were ipsilateral. Two of the nuclei outlined by neostriatal projections in this study, HVc and RA, have important roles in the motor control of canary song (Nottebohm et al., '76). The development of song is dependent on auditory information. Auditory-vocal neural connections described here may be involved in song learning.