Avian magnetic compass: fast adjustment to intensities outside the normal functional window

Wiltschko, Wolfgang; Stapput, Katrin; Thalau, Peter; Wiltschko, Roswitha

doi:10.1007/s00114-006-0102-5

Cited by 66 publications

(80 citation statements)

References 22 publications

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“…As an example, simulations are shown in the SI Appendix that reveal a strong dependence of the form and amplitude of the reaction yield anisotropy on the magnetic field intensity in the range 10-100 T (66). Rob-ins are able to adapt relatively quickly to magnetic fields outside their normal functional window (79). This ability would have a natural interpretation in the radical pair model: The bird must learn to recognize a new anisotropy pattern.…”

Section: Evidence For Radical Pair Magnetoreceptionmentioning

confidence: 99%

Chemical magnetoreception in birds: The radical pair mechanism

Rodgers

Hore²

2009

Proc. Natl. Acad. Sci. U.S.A.

476

449

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Migratory birds travel vast distances each year, finding their way by various means, including a remarkable ability to perceive the Earth's magnetic field. Although it has been known for 40 years that birds possess a magnetic compass, avian magnetoreception is poorly understood at all levels from the primary biophysical detection events, signal transduction pathways and neurophysiology, to the processing of information in the brain. It has been proposed that the primary detector is a specialized ocular photoreceptor that plays host to magnetically sensitive photochemical reactions having radical pairs as fleeting intermediates. Here, we present a physical chemist's perspective on the ''radical pair mechanism'' of compass magnetoreception in birds. We outline the essential chemical requirements for detecting the direction of an Earth-strength Ϸ50 T magnetic field and comment on the likelihood that these might be satisfied in a biologically plausible receptor. Our survey concludes with a discussion of cryptochrome, the photoactive protein that has been put forward as the magnetoreceptor molecule.

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Section: Evidence For Radical Pair Magnetoreceptionmentioning

confidence: 99%

Chemical magnetoreception in birds: The radical pair mechanism

Rodgers

Hore²

2009

Proc. Natl. Acad. Sci. U.S.A.

476

449

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“…Longwavelength light might no longer be absorbed by the magnetosensitive molecule, thus preventing the formation of the crucial radical pairs. Magnetic intensities outside the functional window, on the other hand, change the activity pattern on the retina, but this disorientation is only temporary, as birds very soon adapt to the new magnetic intensities (Wiltschko, W. et al 2006a). Fixed-direction responses, in contrast, are mostly observed under extreme light conditions where one would expect radical-pair processes to work properly, but where the imbalance between input from the colour cones appears to interfere with the magnetic compass at a higher level.…”

Section: When and How Do Iron-based Receptors Control Behaviour?mentioning

confidence: 99%

Directional orientation of birds by the magnetic field under different light conditions

Wiltschko

Stapput

Thalau

et al. 2009

J. R. Soc. Interface.

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159

205

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This paper reviews the directional orientation of birds with the help of the geomagnetic field under various light conditions. Two fundamentally different types of response can be distinguished. (i) Compass orientation controlled by the inclination compass that allows birds to locate courses of different origin. This is restricted to a narrow functional window around the total intensity of the local geomagnetic field and requires light from the short-wavelength part of the spectrum. The compass is based on radical-pair processes in the right eye; magnetite-based receptors in the beak are not involved. Compass orientation is observed under 'white' and low-level monochromatic light from ultraviolet (UV) to about 565 nm green light. (ii) 'Fixed direction' responses occur under artificial light conditions such as more intense monochromatic light, when 590 nm yellow light is added to short-wavelength light, and in total darkness. The manifestation of these responses depends on the ambient light regime and is 'fixed' in the sense of not showing the normal change between spring and autumn; their biological significance is unclear. In contrast to compass orientation, fixed-direction responses are polar magnetic responses and occur within a wide range of magnetic intensities. They are disrupted by local anaesthesia of the upper beak, which indicates that the respective magnetic information is mediated by iron-based receptors located there. The influence of light conditions on the two types of response suggests complex interactions between magnetoreceptors in the right eye, those in the upper beak and the visual system.

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“…We exposed the robins prior to the tests for 3 h to a higher magnetic field of 92 µT. As shown previously [31], robins need about 1 h to orient in this field strength. Robins allowed to use their right eye were oriented right away, but this was not so for the left-eyed birds; they took considerably longer.…”

Section: Conditions Required For the Re-activation Of The Left Eye/rimentioning

confidence: 87%

“…Robins cannot spontaneously cope with such field strengths, but become able to orient in it if they had a chance to adjust to this intensity before the tests. In a previous study, 1 h pre-exposure to such a strong field had proven sufficient to allow orientation [31]. We tested two different groups of birds: Group I was pre-exposed with the right eye open and subsequently tested monocularly right-eyed (3pe92R-92R).…”

Section: Pre-exposure In Altered Magnetic Conditionsmentioning

confidence: 99%

“…This appears to be in accordance with the results of discrimination studies mentioned above. The adjustment to higher magnetic intensities means that the birds become able to interpret a slightly different activation pattern on the retina (see [16,31]); it can start only after the ability to process magnetic information has been restored to left eye/right hemispheres. However, this alone can probably not account for the longer delay of the left eye system, as our experiments show that it requires only 1 1 /2 h, possibly less.…”

Section: Conditions Required For the Re-activation Of The Left Eye/rimentioning

confidence: 99%

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Lateralization of the Avian Magnetic Compass: Analysis of Its Early Plasticity

et al. 2017

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Abstract:In European Robins, Erithacus rubecula, the magnetic compass is lateralized in favor of the right eye/left hemisphere of the brain. This lateralization develops during the first winter and initially shows a great plasticity. During the first spring migration, it can be temporarily removed by covering the right eye. In the present paper, we used the migratory orientation of robins to analyze the circumstances under which the lateralization can be undone. Already a period of 1 1 /2 h being monocularly left-eyed before tests began proved sufficient to restore the ability to use the left eye for orientation, but this effect was rather short-lived, as lateralization recurred again within the next 1 1 /2 h. Interpretable magnetic information mediated by the left eye was necessary for removing the lateralization. In addition, monocularly, the left eye seeing robins could adjust to magnetic intensities outside the normal functional window, but this ability was not transferred to the "right-eye system". Our results make it clear that asymmetry of magnetic compass perception is amenable to short-term changes, depending on lateralized stimulation. This could mean that the left hemispheric dominance for the analysis of magnetic compass information depends on lateralized interhemispheric interactions that in young birds can swiftly be altered by environmental effects.

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Avian magnetic compass: fast adjustment to intensities outside the normal functional window

Cited by 66 publications

References 22 publications

Chemical magnetoreception in birds: The radical pair mechanism

Chemical magnetoreception in birds: The radical pair mechanism

Directional orientation of birds by the magnetic field under different light conditions

Lateralization of the Avian Magnetic Compass: Analysis of Its Early Plasticity

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