The inside-out technique: tailoring fiber dissection for the study of the superficial white matter

COEX 

Despite major methodological advances in the exploration of the cerebral white matter (Axer et al., 2011; Beaujoin et al., 2019) and growing interest in short association fibers (SAF) (Guevara et al., 2020), the latter remain underexplored. The examination of these connections through the classical fiber dissection (Ludwig and Klingler, 1956) is significantly impeded by the fact that the procedure involves the removal of the cerebral cortex, leading to a smooth surface where the bundles are scarcely visible, and causing the loss of a substantial portion of the sulco-gyral anatomy. To address the methodological renewal necessary for the accurate analysis of these delicate and superficial structures, we present the novel technique for inside-out fiber dissection of the post-mortem human brain that approaches subcortical fibers from their deep aspect with the preservation of the cortex.