Hot off the press ....
http://www.plosone.org/article/
info%3Adoi%2F10.1371%2Fjournal.pone.0000937
A Visual Pathway Links Brain Structures Active during Magnetic Compass
Orientation in Migratory Birds
Dominik Heyers 1*, Martina Manns 2, Harald Luksch 3, Onur Güntürkün 2,
Henrik Mouritsen 1
PLoS ONE 2(9): e937. doi:10.1371/journal.pone.0000937
September 26, 2007
Abstract
The magnetic compass of migratory birds has been suggested to be
light-dependent. Retinal cryptochrome-expressing neurons and a
forebrain region, “Cluster N”, show high neuronal activity when
night-migratory songbirds perform magnetic compass orientation. By
combining neuronal tracing with behavioral experiments leading to
sensory-driven gene expression of the neuronal activity marker ZENK
during magnetic compass orientation, we demonstrate a functional
neuronal connection between the retinal neurons and Cluster N via the
visual thalamus. Thus, the two areas of the central nervous system
being most active during magnetic compass orientation are part of an
ascending visual processing stream, the thalamofugal pathway.
Furthermore, Cluster N seems to be a specialized part of the visual
wulst. These findings strongly support the hypothesis that migratory
birds use their visual system to perceive the reference compass
direction of the geomagnetic field and that migratory birds “see” the
reference compass direction provided by the geomagnetic field.
A journalist-grade discussion is available at
http://www.int.iol.co.za/
index.php?set_id=1&click_id=143&art_id=nw20070926012237439C598239
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