In 1991, Felleman and Van Essen published their seminal study regarding hierarchical processing in the primate cerebral cortex. Their work encompassed a widescale analysis of connections reported through tracing between 35 regions in the macaque visual cortex, extending from cortical regions to the laminar level. Since then, great strides have been made in the field of MRI neuroimaging of white matter connectivity, also known as connectomics, as well as grey matter laminar composition. In this work, we revisit laminar-level connectivity in the macaque brain using a whole-brain MRI-based approach. We use multi-modal ex-vivo MRI imaging of both white and grey matter, which are then integrated via our simple model of laminar connectivity. This model uses a granularity-based approach to define a set of rules that expands cortical connections to the laminar level. The resulting whole-brain network of macaque cortical laminar connectivity is then validated in the visual cortex by comparison to results from the 1991 study by Felleman and Van Essen. By using an unbiased definition of the cortex that addresses its heterogenous laminar composition, we are able to explore a new avenue of connectomics on the laminar level.
bioRxiv Subject Collection: Neuroscience