fMRI lag structure during waking up from early sleep stages

Alcaide S, Sitt J, Horikawa T, Romano A, Maldonado AC, Ibañez, Sigman M, Kamitani Y, Barttfeld P. 2021. Cortex

Resumen

The brain mechanisms by which we transition from sleep to a conscious state remain largely unknown in humans, partly because of methodological challenges. Here we study a pre-existing dataset of waking up participants originally designed for a study of dreaming (Horikawa, Tamaki, Miyawaki, & Kamitani, 2013) and suggest that suddenly awakening from early sleep stages results from a two-stage process that involves a sequence of cortical and subcortical brain activity. First, subcortical and sensorimotor structures seem to be recruited before most cortical regions, followed by fast, ignition-like whole-brain activation—with frontal regions engaging a little after the rest of the brain. -Second, a comparably slower and possibly mirror-reversed stage might take place, with cortical regions activating before subcortical structures and the cerebellum. This pattern of activation points to a key role of subcortical structures for the initiation and maintainance of conscious states.