Authors: Madeleine I. R. Brodbeck, Verner P. Bingman, Lauren J. Cole, David F. Sherry, Scott A. MacDougall-Shackleton
Year: 2023
Publication: European Journal of Neuroscience
Publication Link: https://onlinelibrary.wiley.com/doi/10.1111/ejn.15995
Keywords: cluster N, geomagnetic compass, migratory restlessness, white-throated sparrow, Zonotrichia albicollis, Zugunruhe
Abstract: Cluster N is a region of the visual forebrain of nocturnally migrating songbirds
that supports the geomagnetic compass of nocturnal migrants. Cluster N
expresses immediate-early genes (ZENK), indicating neuronal activation. This
neuronal activity has only been recorded at night during the migratory season.
Night-to-night variation in Cluster N activity in relation to migratory behaviour
has not been previously examined. We tested whether Cluster N is activated
only when birds are motivated to migrate and presumably engage their
magnetic compass. We measured immediate-early gene activation in Cluster N
of white-throated sparrows (Zonotrichia albicollis) in three conditions:
daytime, nighttime migratory restless and nighttime resting. Birds in the nighttime
migratory restlessness group had significantly greater numbers of ZENKlabelled
cells in Cluster N compared to both the daytime and the nighttime
resting groups. Additionally, the degree of migratory restlessness was
positively correlated with the number of ZENK-labelled cells in the nighttime
migratory restless group. Our study adds to the number of species observed to
have neural activation in Cluster N and demonstrates for the first time that
immediate early gene activation in Cluster N is correlated with the amount of
active migratory behaviour displayed across sampled individuals. We conclude
that Cluster N is facultatively regulated by the motivation to migrate, together
with nocturnal activity, rather than obligatorily active during the migration
season.