Abstract
Diffusion MRI paired with tractography has facilitated a non-invasive exploration of many association, projection, and commissural fiber tracts. However, there is still a scarcity of research studies related to intralobar association fibers. The Dejerines’ (two of the most notable neurologists of 19th century France) gave an in-depth description of the intralobar fibers of the occipital lobe. Unfortunately, their exquisite work has since been sparsely cited in the modern literature. This work gives a modern description of many of the occipital intralobar lobe fibers described by the Dejerines. We perform a virtual dissection and reconstruct the tracts using diffusion MRI tractography. The dissection is guided by the Dejerines’ treatise, Anatomie des Centres Nerveux. As an accompaniment to this article, we provided a French-to-English translation of the treatise portion concerning five intra-occipital tracts, namely: the stratum calcarinum, the stratum proprium cunei, the vertical occipital fasciculus of Wernicke, the transverse fasciculus of the cuneus and the transverse fasciculus of the lingual lobule of Vialet. It was possible to reconstruct all but one of these tracts. For completeness, the recently described sledge runner fasciculus, although not one of the Dejerines’ tracts, was identified and successfully reconstructed.
Highlights
Diffusion magnetic resonance imaging (MRI) paired with tractography has facilitated a non-invasive exploration of many association, projection, and commissural fiber tracts
Using constrained spherical deconvolution (CSD) tractography, this study successfully identified and mapped four of the five occipital intralobar white matter tracts observed by the Dejerines (Fig. 1)
The following descriptions of the tracts are based on a virtual dissection derived from averaged orientation distribution functions (CSD ODFs) from 24 healthy subjects (Figs. 2–6)
Summary
Diffusion MRI paired with tractography has facilitated a non-invasive exploration of many association, projection, and commissural fiber tracts. A more generalised issue with MRIbased tractography studies is that the findings tend to remain speculative, devoid of tangible experimental evidence and ground truth, unlike those of axonal tracer studies[22] To partially overcome these inherent limitations, contemporary researchers can guide their findings through postmortem dissection studies, by consulting the tract tracing literature or historical neuroanatomy texts. We had previously studied dissections by 19th-century neurologists Joseph and Augusta Dejerine with a view to enriching the field’s knowledge and perspectives on long-range association fiber anatomy[29]. It showcased the pertinence of these historical studies and prompted further examination into the Dejerines’ other work on association short-range occipital fibers
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