Virginia TechPhillips, John B.Muheim, RachelJorge, Paulo E.2014-02-072014-02-072010-10Phillips, John B.; Muheim, Rachel; Jorge, Paulo E., "A behavioral perspective on the biophysics of the light-dependent magnetic compass: a link between directional and spatial perception?," J Exp Biol 213, 3247-3255 (2010); doi: 10.1242/_jeb.0207920022-0949http://hdl.handle.net/10919/25346In terrestrial organisms, sensitivity to the Earth's magnetic field is mediated by at least two different magnetoreception mechanisms, one involving biogenic ferromagnetic crystals (magnetite/maghemite) and the second involving a photo-induced biochemical reaction that forms long-lasting, spin-coordinated, radical pair intermediates. In some vertebrate groups (amphibians and birds), both mechanisms are present; a light-dependent mechanism provides a directional sense or 'compass', and a non-light-dependent mechanism underlies a geographical-position sense or 'map'. Evidence that both magnetite-and radical pair-based mechanisms are present in the same organisms raises a number of interesting questions. Why has natural selection produced magnetic sensors utilizing two distinct biophysical mechanisms? And, in particular, why has natural selection produced a compass mechanism based on a light-dependent radical pair mechanism (RPM) when a magnetite-based receptor is well suited to perform this function? Answers to these questions depend, to a large degree, on how the properties of the RPM, viewed from a neuroethological rather than a biophysical perspective, differ from those of a magnetite-based magnetic compass. The RPM is expected to produce a light-dependent, 3-D pattern of response that is axially symmetrical and, in some groups of animals, may be perceived as a pattern of light intensity and/or color superimposed on the visual surroundings. We suggest that the light-dependent magnetic compass may serve not only as a source of directional information but also provide a spherical coordinate system that helps to interface metrics of distance, direction and spatial position.en-USIn Copyrightmagnetic compassradical pair mechanismspatial cognitionsubicularplace cellsHIPPOCAMPAL PLACE CELLSRADICAL-PAIR MECHANISMPHOTORECEPTOR-BASEDMAGNETORECEPTIONNEWT NOTOPHTHALMUS-VIRIDESCENSBLUE-LIGHTPATH-INTEGRATIONCHEMICAL MAGNETORECEPTIONINCLINATION COMPASSVESTIBULAR INPUTMIGRATORY BIRDSArticle - Refereedhttp://jeb.biologists.org/content/213/19/3247.full.pdf+htmlhttps://doi.org/10.1242/jeb.020792