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V3 spinal interneurons (INs) are a group of excitatory INs that play a crucial role in producing balanced and stable gaits in vertebrate animals. In the developing mouse spinal cord, V3 INs arise from the most ventral progenitor domain and form anatomically distinctive subpopulations in adult spinal cords. They are marked by the expression of transcription factor Sim1 postmitotically, but the function of Sim1 in V3 development remains unknown. Here, we used Sim1(Cre) ;tdTomato mice to trace the fate of V3 INs in a Sim1 mutant versus control genetic background during development. In Sim1 mutants, V3 INs are produced normally and maintain a similar position and organization as in wild types before E12.5. Further temporal analysis revealed that the V3 INs in the mutants failed to migrate properly to form V3 subgroups along the dorsoventral axis of the spinal cord. At birth, in the Sim1 mutant the number of V3 INs in the ventral subgroup was normal, but they were significantly reduced in the dorsal subgroup with a concomitant increase in the intermediate subgroup. Retrograde labeling at lumbar level revealed that loss of Sim1 led to a reduction in extension of contralateral axon projections both at E14.5 and P0 without affecting ipsilateral axon projections. These results demonstrate that Sim1 is essential for proper migration and the guidance of commissural axons of the spinal V3 INs.

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Over 100 years ago Sir William Osler made a list of ten readings that should be at the bedside of every medical student reflecting Osler’s broad and prolific reading habits. Time has continued to flow since Osler’s reading list was proposed and thus, its place in current day medical education warrants reflection. Fundamental questions in this respect include: do medical students still read in the same capacity as their century-old counterparts? If so, how widely does Osler’s original reading list apply to current medical students? Finally, what works would today’s medical students recommend having at the bedside? Students representing the classes of 2016 to 2020 were surveyed at Dalhousie Medical School, constituting one of the largest student efforts in the literature to date to provide per- spectives on Osler’s bedside reading list as well as consensus towards an updated library.This study highlights the considerable disconnect between Osler’s original bedside list and reading tendencies of current medical students. Dalhousie medical students predominantly read and are influenced largely by works pertaining to the medical field and physicians, as opposed to the broad selections set forth by Osler.Although this may reflect the changing medical field or the immersive nature of current training, it also urges reflection as to the value Osler saw in his original bedside library and whether these lessons may be lost on future generations of physicians.