Connectivity of the auditory forebrain nuclei in the Guinea Fowl (Numida meleagris)

Summary Injection of tritiated leucine and proline into the nucleus ovoidalis of the Guinea Fowl (Numida meleagris) produces terminal labeling in the palaeostriatum and in three adjacent zones (field L₁–L₃) of the auditory neostriatum (AN). L₂, situated between L₁ and L₃, receives the main input and corresponds to the former field L of Rose. These neuroanatomically defined zones of the auditory neostriatum are also characterized by differing properties of their neurons. Injection of radioactive material into the auditory neostriatum produces labeling of (i) a palaeostriatal, (ii) a ventral hyperstriatal, and (iii) an additional neostriatal area (Nd). Injection into the hyperstriatum ventrale reveals connections (i) to field L₂, (ii) to the palaeostriatum, (iii) to Nd, and (iv) to the archistriatum. After injection into the palaeostriatum, labeling can be observed (i) in the neostriatum dorsale, (ii) in the hyperstriatum ventrale, (iii) in the archistriatum, (iv) in the diencephalic nuclei, nucleus ansae lenticularis and nucleus spiriformis lateralis, and (v) in the mesencephalic nuclei, nucleus tegmenti pedunculo-pontinus and nucleus intercollicularis. These results show that a widespread connectivity exists among primary and presumably higher order auditory areas in the forebrain of birds. Connections also exist between these auditory areas and presumed vocal-motor areas (neostriatum dorsale, archistriatum, nucleus intercollicularis).Abbreviations A Archistriatum - AL Ansa lenticularis - AN Auditory neostriatum - Bas Nucleus basalis - CA Commissura anterior - Cb Cerebellum - CP Commissura posterior - DLP Nucleus dorsolateralis posterior thalami - DTh Dorsal thalamus - E Ectostriatum - EM Nucleus ectomamillaris - FA Tractus fronto-archistriatalis - FPL Fasciculus prosencephali lateralis - GLv Nucleus geniculatus lateralis, pars ventralis - HA Hyperstriatum accessorium - HD Hyperstriatum dorsale - HIS Hyperstriatum intercalatum superius - HV Hyperstriatum ventrale - HVc Hyperstriatum ventrale, pars caudale - I Injection site - ICo Nucleus intercollicularis - ICT Nucleus intercalatus thalami - Imc Nucleus isthmi, pars magnocellularis - Ipc Nucleus isthmi, pars parvocellularis - l₁, L₂, L₃ Auditory neostriatum: zones L₁, L₂, L₃ - LAD Lamina archistriatalis dorsalis - LH Lamina hyperstriatica - LMD Lamina medullaris dorsalis - LPO Lobus parolfactorius - M Mesencephalon - MLd Nucleus mesencephalicus lateralis, pars dorsalis - N Neostriatum - nAL Nucleus ansae lenticularis - Nc Neostriatum caudale - Nd Neostriatum dorsale - OM Tractus occipito-mesencephalicus - OMv Nucleus nervi oculomotorii, pars ventralis - Ov Nucleus ovoidalis - PA Palaeostriatum augmentatum - PP Palaeostriatum primitivum - PT Nucleus praetectalis - PVM Nucleus periventricularis magno-cellularis - RSd Nucleus reticularis superior, pars dorsalis - RSv Nucleus reticularis superior, pars ventralis - Rt Nucleus rotundus - SMe Stria medullaris - SpL Nucleus spiriformis lateralis - SpM Nucleus spiriformis medialis - SRt Nucleus subrotundus - TeO Tectum opticum - TOv Tractus ovoidalis - TPc Nucleus tegmenti pedunculo-pontinus - TrO Tractus opticus - TSM Tractus septo-mesencephalicus - Ve Ventricle The authors are indebted to Mrs. I. Röder and Mrs. M. Hansel for their aid in the preparation of the histological material and the illustrationsThis work was supported by the Deutsche Forschungsgemeinschaft, Sche 132/4