title: A stereotaxic, population-averaged T1w ovine brain atlas including cerebral morphology and tissue volumes.
abstract: Standard stereotaxic reference systems play a key role in human brain studies. Stereotaxic coordinate systems have also been developed for experimental animals including non-human primates, dogs, and rodents. However, they are lacking for other species being relevant in experimental neuroscience including sheep. Here, we present a spatial, unbiased ovine brain template with tissue probability maps (TPM) that offer a detailed stereotaxic reference frame for anatomical features and localization of brain areas, thereby enabling inter-individual and cross-study comparability. Three-dimensional data sets from healthy adult Merino sheep (Ovis orientalis aries, 12 ewes and 26 neutered rams) were acquired on a 1.5 T Philips MRI using a T1w sequence. Data were averaged by linear and non-linear registration algorithms. Moreover, animals were subjected to detailed brain volume analysis including examinations with respect to body weight (BW), age, and sex. The created T1w brain template provides an appropriate population-averaged ovine brain anatomy in a spatial standard coordinate system. Additionally, TPM for gray (GM) and white (WM) matter as well as cerebrospinal fluid (CSF) classification enabled automatic prior-based tissue segmentation using statistical parametric mapping (SPM). Overall, a positive correlation of GM volume and BW explained about 15% of the variance of GM while a positive correlation between WM and age was found. Absolute tissue volume differences were not detected, indeed ewes showed significantly more GM per bodyweight as compared to neutered rams. The created framework including spatial brain template and TPM represent a useful tool for unbiased automatic image preprocessing and morphological characterization in sheep. Therefore, the reported results may serve as a starting point for further experimental and/or translational research aiming at in vivo analysis in this species.
authors.affiliation: Department of Cell Therapy, Fraunhofer Institute for Cell Therapy and Immunology Leipzig, Germany ; Faculty of Veterinary Medicine, Institute of Anatomy, Histology and Embryology, University of Leipzig Leipzig, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Nitzsche
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Frey
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada.
authors.forename: Louis D
authors.initials: LD
authors.lastname: Collins
authors.affiliation: Faculty of Veterinary Medicine, Institute of Anatomy, Histology and Embryology, University of Leipzig Leipzig, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Seeger
authors.affiliation: Department of Neuroradiology, University Hospital of Leipzig Leipzig, Germany.
authors.forename: Donald
authors.initials: D
authors.lastname: Lobsien
authors.affiliation: Department of Cell Therapy, Fraunhofer Institute for Cell Therapy and Immunology Leipzig, Germany ; Translational Centre for Regenerative Medicine, University of Leipzig Leipzig, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Dreyer
authors.affiliation: Department of Cell Therapy, Fraunhofer Institute for Cell Therapy and Immunology Leipzig, Germany ; Faculty of Medicine, Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig Leipzig, Germany ; LIFE Center (Leipzig Interdisciplinary Research Cluster of Genetic Factors, Phenotypes and Environment), University of Leipzig Leipzig, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Kirsten
authors.affiliation: Division of Veterinary Anatomy, Vetsuisse Faculty, University of Bern Bern, Switzerland.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Stoffel
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada.
authors.forename: Vladimir S
authors.initials: VS
authors.lastname: Fonov
authors.affiliation: Department of Cell Therapy, Fraunhofer Institute for Cell Therapy and Immunology Leipzig, Germany ; Translational Centre for Regenerative Medicine, University of Leipzig Leipzig, Germany ; Neurovascular Regulation Laboratory at Neuroscience Center, Massachusetts General Hospital and Harvard Medical School Charlestown, MA, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Boltze
keywords: SPM; atlas; brain; sheep; stereotaxy; structural MRI; tissue segmentation