THE PORCINE CORTICOSPINAL DECUSSATION: A COMBINED NEURONAL TRACING AND TRACTOGRAPHY STUDY

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  • Johannes Bech
  • Andreas N Glud
  • Ryan Sangill
  • Mikkel Petersen, Center of Functionally Integrative Neuroscience (CFIN) Department of Clinical Medicine Aarhus University Nørrebrogade 44 8000 Aarhus C Denmark.
  • ,
  • Jesper Frandsen, Center of Functionally Integrative Neuroscience (CFIN) Department of Clinical Medicine Aarhus University Nørrebrogade 44 8000 Aarhus C Denmark.
  • ,
  • Dariusz Orlowski
  • Mark J West
  • Michael Pedersen
  • Jens Christian H Sørensen
  • Tim B Dyrby, Danish Research Centre for Magnetic Resonance, Center for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, DK-2650 Hvidovre, Denmark; Dept. of Applied Mathematics and Computer Science, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
  • ,
  • Carsten R Bjarkam, Dept. of Neurosurgery, Department of Clinical Medicine, Aalborg University Hospital, DK-9100 Aalborg, Denmark.

BACKGROUND: Pigs and minipigs are increasingly used as non-primate large animal models for preclinical research on nervous system disorders resulting in motor dysfunction. Knowledge of the minipig pyramidal tract is therefore essential to support such models.

AIM AND METHODS: This study used 5 female Göttingen minipigs aging 11-15 months. The Göttingen minipig corticospinal tract was investigated, in the same animals, with in vivo neuronal tracing and with postmortem diffusion weighted MRI tractography to provide a thorough insight in the encephalic distribution of this primary motor pathway and its decussation at the craniocervical junction.

RESULTS: The two methods similarly outlined the course of the pyramidal tract from its origin in the motor cortex down through the internal capsule to the craniocervical junction, where both methods displayed an axonal crossover at the pyramid decussation. The degree of crossover was quantified with unbiased stereology, where 81-93% of the traced corticospinal fibers crossed to the contralateral spinal cord. Accordingly, in the upper cervical spinal cord the corticospinal tract is primarily distributed in the contralateral lateral funiculus and in close relation to the gray matter, wherein some direct terminations on large ventral column gray matter neurons could be identified.

DISCUSSION: The combination of neuronal tracing and tractography exploited the strengths of the respective methods to gain a better understanding of the encephalic distribution and craniocervical decussation of the Göttingen minipig corticospinal tract. Moreover, a quantification of the crossing fibers was obtained from the tracing data, which was not possible with tractography. Our data indicate that the porcine corticospinal system is quite lateralized down to the investigated upper cervical levels. However, further elucidation of this point will require a full examination of the corticospinal tracing pattern into the caudal spinal cord combined with an analysis of the direct versus indirect termination pattern on the lower motor neurons.

Original languageEnglish
JournalBrain Research Bulletin
ISSN0361-9230
DOIs
Publication statusPublished - Sep 2018

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