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Magnetic Resonance Imaging (MRI) tools to study the sheep brain

A digital modeling (template) and a high-resolution MRI (Magnetic Resonance Imaging) atlas of the sheep's brain were created. These tools now allow the use of different approaches based on brain imaging techniques in neuroscience and behavior studies in sheep.

Stereotaxic atlas of sheep brain. © INRA, Matthieu Keller
By Sylvie André
Updated on 08/03/2017
Published on 04/27/2017

Context and challenge:

The use of many neuro-imaging approaches by magnetic resonance imaging (MRI) is based on the availability and the use of key tools, which are specific to each model animal. Achieving a digital modeling and a high-resolution MRI atlas of a brain, were tools previously not available in sheep. In the field of neuroscience, it allows investigation of neuroanatomical and functional bases of behavioral, neuroendocrine and cognitive processes in domestic animals.

Results:

We computed a template resulting from the registration and averaging of 18 brains of Ile-de-France ewe, a breed commonly used in neuroscience and animal physiology studies. This template is multimodal as it was obtained using the two major types of MRI sequences, i.e. T1 and T2 sequences which provide different contrast images and are therefore complementary. Moreover, this template is probabilistic and was achieved in parallel with the segmentation of three major types of brain tissue that are white matter, gray matter, and cerebrospinal fluid. This realization corresponds to the first scientific publication of the imaging platform CIRE (http://www6.val-de-loire.inra.fr/cire) inaugurated in 2013.

llustration: Multimodal Template. Axial slices of aligned ((upper row) T1 and (bottom row) T2 sequences) template images from (left) down to the (right) top of the brain. © Matthieu Keller
llustration: Multimodal Template. Axial slices of aligned ((upper row) T1 and (bottom row) T2 sequences) template images from (left) down to the (right) top of the brain. © Matthieu Keller

In addition, thanks to the resources available within the CIRE platform of the PRC unit, including the availability of a 3 Tesla MRI, we have developed a digital atlas of the brain of a sheep resulting of the segmentation and of the annotation of various brain structures. This atlas references more than fifty brain structures within a stereotaxic space is accompanied by tissue probability maps. This tool is a prerequisite to any neuroanatomical study on this animal model.

  Atlas stéréotaxique du cerveau ovin. © INRA, Matthieu Keller
Atlas stéréotaxique du cerveau ovin © INRA, Matthieu Keller

Perspectives:

These achievements will allow the development of different types of brain imaging (functional MRI, morphometry, diffusion imaging…) and enable the development of the sheep as a model for both preclinical and fundamental neuro-imaging. This tool will be made ​​available to the scientific community for download via a dedicated website in the future.

Contact(s)
Scientific contact(s):

Associated Division(s):
Animal Physiology and Livestock Systems
Associated Centre(s):
Val de Loire

References

Ella A., Delgadillo J.A., Chemineau P. & Keller M. (2017). Computation of a MRI high resolution 3D stereotaxic atlas of the sheep Brain. The Journal of Comparative Neurology, , 525, 3, 676-692.

Ella A. & Keller M. (2015). Construction of a MRI 3D high resolution sheep brain template. Magnetic Resonance Imaging, 33(10):1329-37. doi: 10.1016/j.mri.2015.09.001