Functional MRI of the zebra finch brain during song stimulation suggests a lateralized response topography

*Citigroup Biomedical Imaging Center, Weill Medical College of Cornell University, 516 East 72nd Street, New York, NY 10021;
^‡Weierstrass Institute for Applied Analysis and Stochastics, Mohrenstrasse 39, 10117 Berlin, Germany;
^§Department of Biology, City College of New York, 138th Street and Convent Avenue, New York, NY 10031; and
^¶The Methodist Neurological Institute, 6560 Fannin Street, Suite 902, Houston, TX 77030

Edited by Dale Purves, Duke University Medical Center, Durham, NC, and approved May 8, 2007 (received for review December 22, 2006)

Abstract

Electrophysiological and activity-dependent gene expression studies of birdsong have contributed to the understanding of the neural representation of natural sounds. However, we have limited knowledge about the overall spatial topography of song representation in the avian brain. Here, we adapt the noninvasive functional MRI method in mildly sedated zebra finches (Taeniopygia guttata) to localize and characterize song driven brain activation. Based on the blood oxygenation level-dependent signal, we observed a differential topographic responsiveness to playback of bird's own song, tutor song, conspecific song, and a pure tone as a nonsong stimulus. The bird's own song caused a stronger response than the tutor song or tone in higher auditory areas. This effect was more pronounced in the medial parts of the forebrain. We found left–right hemispheric asymmetry in sensory responses to songs, with significant discrimination between stimuli observed only in the right hemisphere. This finding suggests that perceptual responses might be lateralized in zebra finches. In addition to establishing the feasibility of functional MRI in sedated songbirds, our results demonstrate spatial coding of song in the zebra finch forebrain, based on developmental familiarity and experience.

Footnotes

^†To whom correspondence should be addressed. E-mail: hev2006{at}med.cornell.edu
Author contributions: D.B. and S.A.H. contributed equally to this work; H.U.V., D.S.-C., D.B., and S.A.H. designed research; H.U.V., K.K.M., and S.A.H. performed research; H.U.V., K.T., and J.P. contributed new reagents/analytic tools; H.U.V., K.T., and J.P. analyzed data; and H.U.V., K.T., J.P., O.T., K.K.M., D.S.-C., D.B., and S.A.H. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0611515104/DC1.
Abbreviations:

LMAN,

lateral magnocellular nucleus of the anterior nidopallium;

NCM,

caudomedial nidopallium;

CM,

caudal mesopallium;

CON,

conspecific song;

BOS,

bird's own song;

TUT,

tutor song;

BOLD,

blood oxygenation level-dependent;

fMRI,

functional MRI;

TONE,

pure tone of 2-kHz frequency;

EPI,

echo-planar imaging;

PS,

propagation–separation.