title: Night-time neuronal activation of Cluster N in a day- and night-migrating songbird.
abstract: Magnetic compass orientation in a night-migratory songbird requires that Cluster N, a cluster of forebrain regions, is functional. Cluster N, which receives input from the eyes via the thalamofugal pathway, shows high neuronal activity in night-migrants performing magnetic compass-guided behaviour at night, whereas no activation is observed during the day, and covering up the birds' eyes strongly reduces neuronal activation. These findings suggest that Cluster N processes light-dependent magnetic compass information in night-migrating songbirds. The aim of this study was to test if Cluster N is active during daytime migration. We used behavioural molecular mapping based on ZENK activation to investigate if Cluster N is active in the meadow pipit (Anthus pratensis), a day- and night-migratory species. We found that Cluster N of meadow pipits shows high neuronal activity under dim-light at night, but not under full room-light conditions during the day. These data suggest that, in day- and night-migratory meadow pipits, the light-dependent magnetic compass, which requires an active Cluster N, may only be used during night-time, whereas another magnetosensory mechanism and/or other reference system(s), like the sun or polarized light, may be used as primary orientation cues during the day.
authors.affiliation: AG Neurosensorik, Institut für Biologie und Umweltwissenschaften, University of Oldenburg, D-26111 Oldenburg, Germany.
authors.forename: Manuela
authors.initials: M
authors.lastname: Zapka
authors.forename: Dominik
authors.initials: D
authors.lastname: Heyers
authors.forename: Miriam
authors.initials: M
authors.lastname: Liedvogel
authors.forename: Erich D
authors.initials: ED
authors.lastname: Jarvis
authors.forename: Henrik
authors.initials: H
authors.lastname: Mouritsen
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003463:Cues; D003624:Darkness; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D008027:Light; D008280:Magnetics; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009949:Orientation / Q000502:physiology; D010775:Photic Stimulation; D020308:Songbirds / Q000033:anatomy & histology / Q000502:physiology
chemical_list: D051766:Early Growth Response Protein 1