[Structures of telencephalic projection in the pigeon. Identification by marking with horseradish peroxidase]

The sites of origin of afferents to the telencephalon in the pigeon were investigated using the HRP technique (TMB). Following large multiple injections of the enzyme into the cerebral hemisphere, peroxidase-positive neurons were identified at diencephalic levels: ipsilaterally in DLM, DMA, DLP, DIP, DMP, Rt, Ov, SRt and SCE/SCI; bilaterally in DLA and SPC. At mesencephalic and posterior brainstem levels, HRP-labeled neurons were found: ipsilaterally in AVT, ZpNIII, ICo, FRM, FRL, TP and SCv; bilaterally in GCt, ZpFLM, neurons were found: ipsilaterally in AVT, ZpNIII, ICo, FRM, FRL, TP and SCv; bilaterally in GCt, ZpFLM, Annul, LoC, LC and PrV. Smaller injections of HRP into different regions of the telencephalon demonstrated, for some of the latter structures, either single or multiple projections upon topographically distinct subdivisions.