Combining fiber dissection, plastination, and tractography for neuroanatomical education: Revealing the cerebellar nuclei and their white matter connections

Abstract

In recent years, there has been a growing interest in white matter anatomy of the human brain. With advances in brain imaging techniques, the significance of white matter integrity for brain function has been demonstrated in various neurological and psychiatric disorders. As the demand for interpretation of clinical and imaging data on white matter increases, the needs for white matter anatomy education are changing. Because cross-sectional images and formalin-fixed brain specimens are often insufficient in visualizing the complexity of three-dimensional (3D) white matter anatomy, obtaining a comprehensible conception of fiber tract morphology can be difficult. Fiber dissection is a technique that allows isolation of whole fiber pathways, revealing 3D structural and functional relationships of white matter in the human brain. In this study, we describe the use of fiber dissection in combination with plastination to obtain durable and easy to use 3D white matter specimens that do not require special care or conditions. The specimens can be used as a tool in teaching white matter anatomy and structural connectivity. We included four human brains and show a series of white matter specimens of both cerebrum and cerebellum focusing on the cerebellar nuclei and associated white matter tracts, as these are especially difficult to visualize in two-dimensional specimens and demonstrate preservation of detailed human anatomy. Finally, we describe how the integration of white matter specimens with radiological information of new brain imaging techniques such as diffusion tensor imaging tractography can be used in teaching modern neuroanatomy with emphasis on structural connectivity.

Neuroanatomy: The added value of the Klingler method

“…For example, the extensive removal of the surrounding brain tissue could impede the correlation of white matter tracts with cortical terminations as the destruction of the adjacent brain structures eliminates important cortical landmarks for the establishment of precise three-dimensional relationships of a specific fiber tract (Agrawal et al, 2011;Arnts et al, 2014). In addition, a dissection could be easily ruined by damaging or cutting through the tract one is trying to reveal (Kier et al, 2004).…”

“…This was related to the fragility of the fibers that break easily and if there is a split along the surface it is difficult to correct. Fiber crossings represent another problem as it is necessary to cut the crossing fibers, in order to continue to dissect and isolate the tract of interest (Arnts et al, 2014;Zemmoura et al, 2015). As a consequence, it is not possible to achieve the dissection of numerous tracts in the same specimen using this methodology (Zemmoura et al, 2015).…”

“…However, as noted by some neuroanatomy medical teachers (Ojeda and Icardo, 2011;Arnts et al, 2014), dissections of the brain white matter are rarely presented to medical students in the neuroanatomy curriculum. Therefore, it is our purpose to demonstrate the potential of the application of the Klingler method and the use of the dissected brains as a teaching tool for undergraduate neuroanatomy medical students.…”

“…This knowledge is relevant for future medical practice due to the development of imagiological techniques, particularly the diffusion-based tractography that provides the reconstruction of virtual three-dimensional representations of the brain white matter tracts in vivo (Ojeda and Icardo, 2011;Le Bihan and Johansen-Berg, 2012;Arnts et al, 2014). Also, the understanding of fiber tracts is important for undergraduate students as there are many diseases that affect the organized fiber systems linking them to several brain regions (Ojeda and Icardo, 2011;Arnts et al, 2014). As an example of this relevance, the two last editions of Gray's Anatomy (Standring, 2008(Standring, , 2015 present two different tractographic reconstructions on their front covers.…”

“…In the formalin-fixed brain specimens, the white matter appears mostly white and homogeneous and it is not possible to visualize the origin, course and termination of the tracts. Hence, medical students struggle to obtain a comprehensible conception of the white matter morphology (Arnts et al, 2014).…”