The similarity between two patches \(p_{i}\) and \(p_{j}\) can be assessed using simple metrics, such as the cosine similarity between their directions \(s_{ij}=\hat{u}_{i}\cdot\hat{u}_{j}\). Across subjects, homotopic and heterotopic patches were defined as patches in the same or different locations, respectively, on the standard surface mesh (Figure 1b).