Event Abstract

Multimodal stereotactic template of the gray short-tailed opossum's brain

  • 1 Nencki Institute of Experimental Biology PAS, Poland
  • 2 H. Niewodniczański Institute of Nuclear Physics PAS, Poland

The gray short-tailed opossum (Monodelphis domestica) in an increasingly popular laboratory animal due to the early stage of development of its newborns born at 14 PCD, which makes this species particularly useful in developmental and comparative neurobiology. However, while a number of studies were performed on the opossum brain, still, a consistent and comprehensive neuroanatomical reference is not available. Moreover, there is no stereotactic coordinate system defined which makes procedures like brain lesions or tracer injections more difficult to perform and less accurate. The aim of this study is to provide a multimodal stereotactic template of the Monodelphis opossum brain to enhance usefulness of this species as a convenient model in neurobiological research.

Data of four modalities were acquired from a single one-year old male specimen preserved in formalin: (1) T1/T2* magnetic resonance image collected using Bruker BioSpec 9.4T imaging system with the isotropic resolution of 50um. (2) Photographs of the tissue block taken during cryosectioning ('blockface' images) acquired with the camera placed in front of the cryostat. (3 and 4) Series of 40um thick coronal Nissl- and myelin stained slices across the whole brain, 264 slices each.

During the data integration process, the blockface images were rigidly coregistered to one another to remove cryostat shaft's jitter and were stacked into a single volume. Then, reconstruction of the brain from both series of stained slices was performed. First, images of the stained slices were rigidly registered to corresponding blockface images, then the slices' images were sequentially aligned to a reference slice from the middle of the stack. However, the rigid alignment did not correct distortions of individual sections like tearing, folding or loosing some of its parts. Therefore, deformable reconstruction routine was used to assure a smooth shape of the histological volumes. By iteratively deforming consecutive slices towards the average of their neighbors, the procedure corrected the most distorted slices, forced smooth reconstruction of the brain outline, and significantly improved the shapes of the internal brain structures. Computed deformation fields were then visualized and quantitatively analyzed to highlight the areas with the highest amount of deformation. Finally, blockface volume, and those based on series of stained slices were affinely aligned to the MRI volume which resulted in the complete multimodal template.

The stereotactic coordinate system was established by examining microtomography (micro-CT) image of the opossum's skull acquired with the X-Tek (Nikon) Benchtop CT160Xi microtomograph with the 41um isotropic resolution. Coronal, Lambdoid and Sagittal sutures were identified as well as ear canals and dental chiasma, which allowed to locate bregma and lambda anatomical points, define interaural line and thus, to express locations within the brain with respect to the defined landmarks.

The obtained template allows for slicing the brain at arbitrary planes and for performing any other type of volumetric analyzes. Four data modalities constituting the template facilitate the ongoing process of delineating individual brain structures. Moreover, other experimental results like data acquired from various immunohistochemical stains will be mapped into the template in the future.

Figure 1

Acknowledgements

The project is partly supported by an infrastructural grant from the Polish Ministry of Regional Development POIG.02.03.00-00-003/09.

Keywords: atlasing, MRI, Magnetic Resonance Imaging, opossum, Histological Techniques, multimodal integration, Multimodal Imaging, Stereotaxic Techniques

Conference: Neuroinformatics 2013, Stockholm, Sweden, 27 Aug - 29 Aug, 2013.

Presentation Type: Poster

Topic: Digital atlasing

Citation: Majka P, Chlodzinska N, Banasik T, Djavadian R, Węglarz W, Turlejski K and Wójcik DK (2013). Multimodal stereotactic template of the gray short-tailed opossum's brain. Front. Neuroinform. Conference Abstract: Neuroinformatics 2013. doi: 10.3389/conf.fninf.2013.09.00021

Received: 04 Apr 2013; Published Online: 11 Jul 2013.

* Correspondence: Mr. Piotr Majka, Nencki Institute of Experimental Biology PAS, Warsaw, Poland, pmajka@nencki.gov.pl

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