CONNECTIONS OF THE DORSOMEDIAL PART OF THE NUCLEUS INTERCOLLICULARIS IN A MALE NON-SONGBIRD, THE GREY PARTRIDGE - A TRACT-TRACING STUDY

Vocal control systems have been poorly investigated in non-songbirds. In this study we describe descending neural pathways to the dorsomedia l portion of the nucleus intercollicularis (ICo) in a galliform (male Grey partridges) by means of the DiI in vitro tracing technique. The s imple and sex-dimorphic vocalizations of partridges, which have a crit ical role in sexual selection, favour this species as a model system f or the study of vocal control mechanisms. Our data demonstrate that th e ICo, an important site mediating the activation of vocal behavior in all birds, receives afferents from several important higher centers: the nucleus pretectalis, the tuberoinfundibular hypothalamic region, t he dorsal thalamus, the preoptic region and the paleostriatal region. Efferent connections of the ICo were directed mainly to the hypothalam ic area. This complex neural pathway is consistent with a major role o f ICo in male courtship and vocal performance control. (C) 1996 Elsevi er Science Ireland Ltd.