White matter connections within the central sulcus subserving the somato-cognitive action network.

The somato-cognitive action network (SCAN) consists of three nodes interspersed within Penfield's motor effector regions. The configuration of the somato-cognitive action network nodes resembles the one of the 'plis de passage' of the central sulcus: small gyri bridging the precentral and postcentral gyri. Thus, we hypothesize that these may provide a structural substrate of the somato-cognitive action network. Here, using microdissections of sixteen human hemispheres, we consistently identified a chain of three distinct plis de passage with increased underlying white matter, in locations analogous to the somato-cognitive action network nodes. We mapped localizations of plis de passage into standard stereotactic space to seed fMRI connectivity across 9,000 resting-state fMRI scans, which demonstrated the connectivity of these sites with the somato-cognitive action network. Intraoperative recordings during direct electrical central sulcus stimulation further identified inter-effector regions corresponding to plis de passage locations. This work provides a critical step towards improved understanding of the somato-cognitive action network in both structural and functional terms. Further, our work has the potential to guide the development of refined motor cortex stimulation techniques for treating brain disorders, and operative resective techniques for complex surgery of the motor cortex.