Night-time neuronal activation of Cluster N in a day- and night-migrating songbird

AG Neurosensorik, Institut für Biologie und Umweltwissenschaften, University of Oldenburg, D-26111 Oldenburg, Germany.
European Journal of Neuroscience (Impact Factor: 3.18). 08/2010; 32(4):619-24. DOI: 10.1111/j.1460-9568.2010.07311.x
Source: PubMed


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.

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    • "It seems that the common pattern of avian navigational processes, regardless of the spe­ cific mechanism used, is to establish the direction to distant goals by using an external reference as a com­ pass course (Wiltschko and Wiltschko, 1998). To do this, birds perceive visual (Lipp et al., 2004; Biro et al., 2007), auditory (Hagstrum, 2001; Moore, 2004), olfactory (Wallraff, 2004; Jouventin et al., 2007), and magnetic cues (Stapput et al., 2008; Henshaw et al., 2010; Zapka et al., 2010) and use them for orientation (reviewed by Wiltschko and Wiltschko, 2003). However, the neurobiological basis underlying migratory behavior is still largely unknown (Wiltschko and Wiltschko, 2003; Alerstam, 2006) and only a few studies support the hypothesis that migratory habits may affect memory and the brain. "
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    ABSTRACT: Evidence suggests a possible correlation between learning abilities of adults and new neuronal recruitment into their brains. The hypothesis is that this brain plasticity enables animals to adapt to environmental changes. We examined whether there are differences in neuronal recruitment between resident and migrant birds. We predicted that migrants, which are more exposed to spatial changes than residents, will recruit more new neurons. To test this, we compared neuronal recruitment in two closely related bird species - the migrant reed warbler (Acrocephalus scirpaceus), and the resident Clamorous warbler (A. Stentoreus) - during spring, summer and autumn. Wild birds were caught, treated with BrdU and sacrificed five weeks later. New neurons were recorded in the Hippocampus and Nidopallium caudolateral. The results support our hypothesis, as more new neurons were found in the migrant species, in both brain regions and all seasons. We suggest that this phenomenon enables enhanced navigational abilities which are required for the migratory lifestyle. However, in contrast to our hypothesis, in spring we found less new neurons in adults of both species, compared to other seasons. We suggest that in spring, when birds settle in breeding territories, they require less spatial skills, and this might enable to reduce the cost of neuronal recruitment, as reflected by less new neurons in their brains. We also found age differences, with overall higher neuronal recruitment in juveniles. Finally, we advocate the importance of studying wild populations, for a better understanding of the adaptive significance of neuronal replacement in the vertebrate brain.
    Full-text · Article · Dec 2014 · Developmental Neurobiology
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    • "Each year, migratory birds travel long distances between their breeding grounds and their wintering quarters, and it is well established that they use a light-dependent magnetic compass for orientation [1]–[11]. The direction of the Earth's magnetic field is supposedly sensed by radical pair-forming, light-dependent photopigments in the birdś eyes [4], [11]–[20] and then processed in Cluster N, a specialized, night-time active, light-processing forebrain region [9], [21]–[24] which is required for magnetic compass orientation [10]. "
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    ABSTRACT: Previous studies on European robins, Erithacus rubecula, and Australian silvereyes, Zosterops lateralis, had suggested that magnetic compass information is being processed only in the right eye and left brain hemisphere of migratory birds. However, recently it was demonstrated that both garden warblers, Sylvia borin, and European robins have a magnetic compass in both eyes. These results raise the question if the strong lateralization effect observed in earlier experiments might have arisen from artifacts or from differences in experimental conditions rather than reflecting a true all-or-none lateralization of the magnetic compass in European robins. Here we show that (1) European robins having only their left eye open can orient in their seasonally appropriate direction both during autumn and spring, i.e. there are no strong lateralization differences between the outward journey and the way home, that (2) their directional choices are based on the standard inclination compass as they are turned 180° when the inclination is reversed, and that (3) the capability to use the magnetic compass does not depend on monocular learning or intraocular transfer as it is already present in the first tests of the birds with only one eye open.
    Full-text · Article · Sep 2012 · PLoS ONE
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    • "“Cluster N” receives input from the retina via the visual thalamofugal pathway [35], and lesions of this area in robins eliminate magnetic field orientation [36]. However, “Cluster N” is not activated during the day [34], not even during daytime migration of a day- and night-migrating bird [37] and can also not be identified in other birds, which have been shown to orient after the magnetic field (e.g. zebra finches; [34]). "
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    ABSTRACT: Many animals are able to perceive the earth magnetic field and to use it for orientation and navigation within the environment. The mechanisms underlying the perception and processing of magnetic field information within the brain have been thoroughly studied, especially in birds, but are still obscure. Three hypotheses are currently discussed, dealing with ferromagnetic particles in the beak of birds, with the same sort of particles within the lagena organs, or describing magnetically influenced radical-pair processes within retinal photopigments. Each hypothesis is related to a well-known sensory organ and claims parallel processing of magnetic field information with somatosensory, vestibular and visual input, respectively. Changes in activation within nuclei of the respective sensory systems have been shown previously. Most of these previous experiments employed intensity enhanced magnetic stimuli or lesions. We here exposed unrestrained zebra finches to either a stationary or a rotating magnetic field of the local intensity and inclination. C-Fos was used as an activity marker to examine whether the two treatments led to differences in fourteen brain areas including nuclei of the somatosensory, vestibular and visual system. An ANOVA revealed an overall effect of treatment, indicating that the magnetic field change was perceived by the birds. While the differences were too small to be significant in most areas, a significant enhancement of activation by the rotating stimulus was found in a hippocampal subdivision. Part of the hyperpallium showed a strong, nearly significant, increase. Our results are compatible with previous studies demonstrating an involvement of at least three different sensory systems in earth magnetic field perception and suggest that these systems, probably less elaborated, may also be found in nonmigrating birds.
    Full-text · Article · Jun 2012 · PLoS ONE
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