Efferent projections of the visual Wulst upon the nucleus of the basal optic root in the pigeon.

Efferent projections of the visual Wulst upon the nucleus of the basal optic root (nBOR) were investigated using various neuroanatomical approaches: optical and EM orthograde degeneration methods (following visual Wulst ablation), radioautographic and HRP techniques (following injection of various tracers within the visual Wulst). The radioautographic and electron microscope degeneration experiments clearly demonstrated a visual Wulst projection upon the ipsilateral nBORl and the lateral portions of nBORd and nBORp. The pigeon's hyperstriato-nBOR projection is compared to a similar descending visual cortico-accessory optic pathway in mammals and its possible role in the control of oculomotor function is discussed.