title: Magnetic field-driven induction of ZENK in the trigeminal system of pigeons (Columba livia).
abstract: Magnetoreception remains one of the few unsolved mysteries in sensory biology. The upper beak, which is innervated by the ophthalmic branch of the trigeminal nerve (V1), has been suggested to contain magnetic sensors based on ferromagnetic structures. Recently, its existence in pigeons has been seriously challenged by studies suggesting that the previously described iron-accumulations are macrophages, not magnetosensitive nerve endings. This raised the fundamental question of whether V1 is involved in magnetoreception in pigeons at all. We exposed pigeons to either a constantly changing magnetic field (CMF), to a zero magnetic field providing no magnetic information, or to CMF conditions after V1 was cut bilaterally. Using immediate early genes as a marker of neuronal responsiveness, we report that the trigeminal brainstem nuclei of pigeons, which receive V1 input, are activated under CMF conditions and that this neuronal activation disappears if the magnetic stimuli are removed or if V1 is cut. Our data suggest that the trigeminal system in pigeons is involved in processing magnetic field information and that V1 transmits this information from currently unknown, V1-associated magnetosensors to the brain.
authors.affiliation: AG Neurosensorik/Animal Navigation, Institute of Biological and Environmental Sciences, University Oldenburg, 26111 Oldenburg, Germany.
authors.forename: Nele
authors.initials: N
authors.lastname: Lefeldt
authors.affiliation: AG Neurosensorik/Animal Navigation, Institute of Biological and Environmental Sciences, University Oldenburg, 26111 Oldenburg, Germany dominik.heyers@uni-oldenburg.de.
authors.forename: Dominik
authors.initials: D
authors.lastname: Heyers
authors.affiliation: AG Neurosensorik/Animal Navigation, Institute of Biological and Environmental Sciences, University Oldenburg, 26111 Oldenburg, Germany.
authors.forename: Nils-Lasse
authors.initials: NL
authors.lastname: Schneider
authors.affiliation: AG Neurosensorik/Animal Navigation, Institute of Biological and Environmental Sciences, University Oldenburg, 26111 Oldenburg, Germany.
authors.forename: Svenja
authors.initials: S
authors.lastname: Engels
authors.affiliation: AG Neurosensorik/Animal Navigation, Institute of Biological and Environmental Sciences, University Oldenburg, 26111 Oldenburg, Germany.
authors.forename: Dana
authors.initials: D
authors.lastname: Elbers
authors.affiliation: AG Neurosensorik/Animal Navigation, Institute of Biological and Environmental Sciences, University Oldenburg, 26111 Oldenburg, Germany.
authors.forename: Henrik
authors.initials: H
authors.lastname: Mouritsen
mesh_terms: D000818:Animals; D010856:Columbidae / Q000502:physiology*; D007501:Iron / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D060526:Magnetic Fields; D010465:Perception / Q000502:physiology*; D012668:Trigeminal Ganglion / Q000378:metabolism*
chemical_list: D007501:Iron
keywords: bird migration; homing; immediate early gene; magnetic sense; trigeminal system