From cortical folding to injury susceptibility: How growth-induced residual stresses influence brain damage

Cortical fold development in the human brain progresses through various stages of wrinkling, primary folding and secondary folding, resulting in complex gyrus-sulcus formation. Differential growth in gray and white matter is a key driver of this morphological sequence. This process, modeled here in terms of a large scale mismatch in growth strain, gives rise to mechanical stress. An intrinsic residual stress is thus present in the fully developed brain structure. We describe a model for determining this growth induced residual stress and then examine its key features. This includes a focus on how tensile and compressive regions correlate with sulcus-gyrus formation, how sulcal wall self contact is affected by secondary folding, how wall self contact affects the stress, and which deep tissue surface orientations may be especially predisposed to microtear. This work considers a new paradigm for brain injury modeling by demonstrating how growth-induced residual stresses fundamentally influence trauma susceptibility, with tensile stress concentrations at gray-white matter interfaces creating preferential sites for injury initiation.