Hierarchical gradient of timescales in the mammalian forebrain

Timescales of temporally correlated neural activity vary systematically along the anatomical hierarchy of the primate cortex. Here, we found a similar hierarchical gradient of timescales in intrinsic as well as task-related cortical activities across monkeys, rats, and mice as they performed decision-making tasks, whereas the timescales of thalamic activity did not follow the anatomical hierarchy of their cortical counterparts. These findings suggest that the hierarchical ordering of cortical timescales may arise from intra-cortical recurrent connectivity rather than transthalamic projections, which reflects an evolutionary principle of cortical specialization shared across mammalian species.