Seasonal rewiring of the songbird brain: an in vivo MRI study.

Full Abstract

The song control system (SCS) of songbirds displays a remarkable plasticity in species where song output changes seasonally. The mechanisms underlying this plasticity are barely understood and research has primarily been focused on the song nuclei themselves, largely neglecting their interconnections and connections with other brain regions. We investigated seasonal changes in the entire brain, including the song nuclei and their connections, of nine male starlings (Sturnus vulgaris). At two times of the year, during the breeding (April) and nonbreeding (July) seasons, we measured in the same subjects cellular attributes of brain regions using in vivo high-resolution diffusion tensor imaging (DTI) at 7 T. An increased fractional anisotropy in the HVC-RA pathway that correlates with an increase in axonal density (and myelination) was found during the breeding season, confirming multiple previous histological reports. Other parts of the SCS, namely the occipitomesencephalic axonal pathway, which contains fiber tracts important for song production, showed increased fractional anisotropy due to myelination during the breeding season and the connection between HVC and Area X showed an increase in axonal connectivity. Beyond the SCS we discerned fractional anisotropy changes that correlate with myelination changes in the optic chiasm and axonal organization changes in an interhemispheric connection, the posterior commissure. These results demonstrate an unexpectedly broad plasticity in the connectivity of the avian brain that might be involved in preparing subjects for the competitive and demanding behavioral tasks that are associated with successful reproduction.

Author information

Author/s: De Groof, Geert (G); Verhoye, Marleen (M); Van Meir, Vincent (V); Balthazart, Jacques (J); Van der Linden, Annemie (A);

Affiliation: Bio-Imaging Lab, University of Antwerp, CGB, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. geert.degroof(-atsign-)ua.ac.be

Grants: R01 NS35467 (Agency:NINDS NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: The European journal of neuroscience (Eur J Neurosci), published in France. (Language: eng)

Reference: 2008-Dec; vol 28 (issue 12) : pp 2475-85; discussion 2474

Dates: Created 2008/12/17; Completed 2009/02/03;

PMID: 19032586, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

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