Logo of biophysjLink to Publisher's site
Biophys J. 2000 Feb; 78(2): 707–718.
PMCID: PMC1300674

A model for photoreceptor-based magnetoreception in birds.


A large variety of animals has the ability to sense the geomagnetic field and utilize it as a source of directional (compass) information. It is not known by which biophysical mechanism this magnetoreception is achieved. We investigate the possibility that magnetoreception involves radical-pair processes that are governed by anisotropic hyperfine coupling between (unpaired) electron and nuclear spins. We will show theoretically that fields of geomagnetic field strength and weaker can produce significantly different reaction yields for different alignments of the radical pairs with the magnetic field. As a model for a magnetic sensory organ we propose a system of radical pairs being 1) orientationally ordered in a molecular substrate and 2) exhibiting changes in the reaction yields that affect the visual transduction pathway. We evaluate three-dimensional visual modulation patterns that can arise from the influence of the geomagnetic field on radical-pair systems. The variations of these patterns with orientation and field strength can furnish the magnetic compass ability of birds with the same characteristics as observed in behavioral experiments. We propose that the recently discovered photoreceptor cryptochrome is part of the magnetoreception system and suggest further studies to prove or disprove this hypothesis.

Full Text

The Full Text of this article is available as a PDF (193K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Beason R, Dussourd N, Deutschlander M. Behavioural evidence for the use of magnetic material in magnetoreception by a migratory bird. J Exp Biol. 1995;198(Pt 1):141–146. [PubMed]
  • Beason R, Semm P. Does the avian ophthalmic nerve carry magnetic navigational information? J Exp Biol. 1996;199(Pt 5):1241–1244. [PubMed]
  • Bialek W. Physical limits to sensation and perception. Annu Rev Biophys Biophys Chem. 1987;16:455–478. [PubMed]
  • Brocklehurst B, McLauchlan KA. Free radical mechanism for the effects of environmental electromagnetic fields on biological systems. Int J Radiat Biol. 1996 Jan;69(1):3–24. [PubMed]
  • Cashmore AR, Jarillo JA, Wu YJ, Liu D. Cryptochromes: blue light receptors for plants and animals. Science. 1999 Apr 30;284(5415):760–765. [PubMed]
  • Deutschlander ME, Borland SC, Phillips JB. Extraocular magnetic compass in newts. Nature. 1999 Jul 22;400(6742):324–325. [PubMed]
  • Deutschlander ME, Phillips JB, Borland SC. The case for light-dependent magnetic orientation in animals . J Exp Biol. 1999 Apr;202(Pt 8):891–908. [PubMed]
  • Edmonds DT. A sensitive optically detected magnetic compass for animals. Proc Biol Sci. 1996 Mar 22;263(1368):295–298. [PubMed]
  • Fite KV, Brecha N, Karten HJ, Hunt SP. Displaced ganglion cells and the accessory optic system of pigeon. J Comp Neurol. 1981 Jan 10;195(2):279–288. [PubMed]
  • Gwinner E. Endogenous temporal control of migratory restlessness in warblers. Naturwissenschaften. 1974 Sep;61(9):405–405. [PubMed]
  • Haberkorn R, Michel-Beyerle ME. On the mechanism of magnetic field effects in bacterial photosynthesis. Biophys J. 1979 Jun;26(3):489–498. [PMC free article] [PubMed]
  • Harkins TT, Grissom CB. Magnetic field effects on B12 ethanolamine ammonia lyase: evidence for a radical mechanism. Science. 1994 Feb 18;263(5149):958–960. [PubMed]
  • Hoff AJ. Magnetic field effects on photosynthetic reactions. Q Rev Biophys. 1981 Nov;14(4):599–665. [PubMed]
  • Hong FT. Magnetic field effects on biomolecules, cells, and living organisms. Biosystems. 1995;36(3):187–229. [PubMed]
  • Kirschvink JL, Gould JL. Biogenic magnetite as a basis for magnetic field detection in animals. Biosystems. 1981;13(3):181–201. [PubMed]
  • Leask MJ. A physicochemical mechanism for magnetic field detection by migratory birds and homing pigeons. Nature. 1977 May 12;267(5607):144–145. [PubMed]
  • Miyamoto Y, Sancar A. Vitamin B2-based blue-light photoreceptors in the retinohypothalamic tract as the photoactive pigments for setting the circadian clock in mammals. Proc Natl Acad Sci U S A. 1998 May 26;95(11):6097–6102. [PMC free article] [PubMed]
  • Mohtat N, Cozens FL, Hancock-Chen T, Scaiano JC, McLean J, Kim J. Magnetic field effects on the behavior of radicals in protein and DNA environments. Photochem Photobiol. 1998 Jan;67(1):111–118. [PubMed]
  • Phillips JB. Two magnetoreception pathways in a migratory salamander. Science. 1986 Aug 15;233(4765):765–767. [PubMed]
  • Phillips JB, Sayeed O. Wavelength-dependent effects of light on magnetic compass orientation in Drosophila melanogaster. J Comp Physiol A. 1993 Apr;172(3):303–308. [PubMed]
  • Sancar A. Structure and function of DNA photolyase. Biochemistry. 1994 Jan 11;33(1):2–9. [PubMed]
  • Schulten K, Weller A. Exploring fast electron transfer processes by magnetic fields. Biophys J. 1978 Oct;24(1):295–305. [PMC free article] [PubMed]
  • Semm P, Demaine C. Neurophysiological properties of magnetic cells in the pigeon's visual system. J Comp Physiol A. 1986 Nov;159(5):619–625. [PubMed]
  • Werner HJ, Schulten K, Weller A. Electron transfer and spin exchange contributing to the magnetic field dependence of the primary photochemical reaction of bacterial photosynthesis. Biochim Biophys Acta. 1978 May 10;502(2):255–268. [PubMed]
  • Wiltschko W, Wiltschko R. Magnetic compass of European robins. Science. 1972 Apr 7;176(4030):62–64. [PubMed]
  • Wiltschko W, Wiltschko R. Magnetic orientation in birds. J Exp Biol. 1996;199(Pt 1):29–38. [PubMed]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society


Save items

Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


  • Compound
    PubChem Compound links
  • PubMed
    PubMed citations for these articles
  • Substance
    PubChem Substance links

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...