Show Reference: "Topographic Projection from the Optic Tectum to the Auditory Space Map in the Inferior Colliculus of the Barn Owl"

Topographic Projection from the Optic Tectum to the Auditory Space Map in the Inferior Colliculus of the Barn Owl The Journal of Comparative Neurology, Vol. 421, No. 2. (29 May 2000), pp. 146-160 by Peter S. Hyde, Eric I. Knudsen
@article{hyde-and-knudsen-2000,
    abstract = {In the barn owl (Tyto alba), the external nucleus of the inferior colliculus ({ICX}) contains a map of auditory space that is calibrated by visual experience. The source of the visually based instructive signal to the {ICX} is unknown. Injections of biotinylated dextran amine and {Fluoro-Gold} in the {ICX} retrogradely labelled neurons in layers 8-15 of the ipsilateral optic tectum ({OT}) that could carry this instructive signal. This projection was point-to-point and in register with the feed-forward, auditory projection from the {ICX} to the {OT}. Most labelled neurons were in layers 10-11, and most were bipolar. Tripolar, multipolar, and unipolar neurons were also observed. Multipolar neurons had dendrites that were oriented parallel to the tectal laminae. In contrast, most labelled bipolar and tripolar neurons had dendrites oriented perpendicular to the tectal laminae, extending superficially into the retino-recipient laminae and deep into the auditory recipient laminae. Therefore, these neurons were positioned to receive both visual and auditory information from particular locations in space. Biocytin injected into the superficial layers of the {OT} labelled bouton-laden axons in the {ICX}. These axons were generally finer than, but had similar bouton densities as, feed-forward auditory fibers in the {ICX}, labelled by injections of biocytin into the central nucleus of the inferior colliculus ({ICC}). These data demonstrate a point-to-point projection from the {OT} to the {ICX} that could provide a spatial template for calibrating the auditory space map in the {ICX}.
                Copyright 2000 {Wiley-Liss}, Inc.},
    author = {Hyde, Peter S. and Knudsen, Eric I.},
    day = {29},
    issn = {0021-9967},
    journal = {The Journal of Comparative Neurology},
    keywords = {alignment, auditory, biology, development, ic, sc},
    month = may,
    number = {2},
    pages = {146--160},
    pmid = {10813778},
    posted-at = {2012-07-16 16:21:00},
    priority = {2},
    title = {Topographic Projection from the Optic Tectum to the Auditory Space Map in the Inferior Colliculus of the Barn Owl},
    url = {http://view.ncbi.nlm.nih.gov/pubmed/10813778},
    volume = {421},
    year = {2000}
}

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Rucci et al.'s model of learning to combine ICx and SC maps does not take into account the point-to-point projections from SC to ICx reported later by Knudsen et al.

The external nucleus of the inferior colliculus (ICx) of the barn owl represents a map of auditory space.

The map of auditory space in the nucleus of the inferior colliculus (ICx) is calibrated by visual experience.

The optic tectum (OT) receives information on sound source localization from ICx.

Hyde and Knudsen found that there is a point-to-point projection from OT to IC.

Mammals seem to have SC-IC connectivity analogous to that of the barn owl.

Hyde and Knudsen elaborate on which neurons in the owl optic tectum (OT) project where.

Hyde and Knudsen propose that the OT-IC projection conveys what they call a "template-based instructive signal" which aligns the auditory space map in ICx with the retinotopic space map in SC.