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Second tectofugal pathway in a songbird (Taeniopygia guttata) revisited: Tectal and lateral pontine projections to the posterior thalamus, thence to the intermediate nidopallium

Wild, J M; Gaede, A H

Authors

J M Wild

A H Gaede



Abstract

Birds are almost always said to have two visual pathways from the retina to the telencephalon: thalamofugal terminating in the Wulst, and tectofugal terminating in the entopallium. Often ignored is a second tectofugal pathway that terminates in the nidopallium medial to and separate from the entopallium (e.g., Gamlin and Cohen [1986] J Comp Neurol 250:296–310). Using standard tract‐tracing and electroanatomical techniques, we extend earlier evidence of a second tectofugal pathway in songbirds (Wild [1994] J Comp Neurol 349:512–535), by showing that visual projections to nucleus uvaeformis (Uva) of the posterior thalamus in zebra finches extend farther rostrally than to Uva, as generally recognized in the context of the song control system. Projections to “rUva” resulted from injections of biotinylated dextran amine into the lateral pontine nucleus (PL), and led to extensive retrograde labeling of tectal neurons, predominantly in layer 13. Injections in rUva also resulted in extensive retrograde labeling of predominantly layer 13 tectal neurons, retrograde labeling of PL neurons, and anterograde labeling of PL. It thus appears that some tectal neurons could project to rUva and PL via branched axons. Ascending projections of rUva terminated throughout a visually responsive region of the intermediate nidopallium (NI) lying between the nucleus interface medially and the entopallium laterally. Lastly, as shown by Clarke in pigeons ([1977] J Comp Neurol 174:535–552), we found that PL projects to caudal cerebellar folia. J. Comp. Neurol. 524:963–985, 2016. © 2015 Wiley Periodicals, Inc.

Citation

Wild, J. M., & Gaede, A. H. (2015). Second tectofugal pathway in a songbird (Taeniopygia guttata) revisited: Tectal and lateral pontine projections to the posterior thalamus, thence to the intermediate nidopallium. Journal of Comparative Neurology, 524(5), 963-985

Journal Article Type Article
Acceptance Date Jul 25, 2015
Publication Date Aug 19, 2015
Deposit Date Jul 15, 2020
Publicly Available Date Jul 15, 2020
Journal Journal of Comparative Neurology
Print ISSN 0021-9967
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 524
Issue 5
Pages 963-985
Public URL https://rvc-repository.worktribe.com/output/1399930
Publisher URL https://doi.org/10.1002/cne.23886

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