The brain exhibits both spatial and temporal hierarchy with their relationship remaining an open question. We address this issue by investigating the brain’s spatial hierarchy with complexity, i.e., Lempel-Zev Complexity (LZC) and temporal dynamics, i.e., median frequency (MF) in rest/task fMRI (including replication data). Our results are: (I) topographical differences in rest between higher-order networks (lower LZC and MF) and lower-order networks (higher LZC and MF); (II) task-specific increases and task-unspecific decreases in LZC and MF; (III) non-linear topographical relationship with low MF mediating higher LZC rest-task changes as confirmed in various simulations. Together, we demonstrate convergence of spatial (LZC) and temporal (MF) hierarchies in a non-linear topographical way along the lines of higher-order/slow frequency and lower-order/fast frequency networks.
bioRxiv Subject Collection: Neuroscience