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.
Highlights
Neuroimaging and accurate stereotaxic neuronavigation is increasingly important in clinical and translational neuroscience
Stereotaxic coordinates are given in mm. (D) Comparison of SNR and CNR: compared to Meanrig, Meanaffine, and the sample GM and white matter (WM) SNRs of Meannl were significantly increased
The major aim of the present approach was to provide a spatial, unbiased standard ovine T1w brain template including tissue probability maps (TPM) for GM, WM, and cerebrospinal fluid (CSF) classifications, and a coordinate system according to Talairach space conventions
Summary
Neuroimaging and accurate stereotaxic neuronavigation is increasingly important in clinical and translational neuroscience. A spatially standardized coordinate system for human subjects based on a single post-mortem brain was defined almost three decades ago (Fox et al, 1985; Talairach and Tournoux, 1988). The stereotaxic space was redefined (Evans et al, 1994) and data sets were linearly scaled to the original Talairach space (Collins et al, 1994, 1995). Non-linear transformation algorithms (Klein et al, 2009) and precise population-averaged high-resolution templates for adults and infants were developed (Fonov et al, 2011), enabling the template to serve as an objectified, morphological, and spatial reference for image analysis of the human brain
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
