Co-activated yet disconnected-Neural correlates of eye closures when trying to stay awake.
Neuroimage September 1, 2015 Ju Lynn Ong, Danyang Kong, Tiffany T Y Chia et al.
When people are sleep-deprived, spontaneous eye closures that signal the onset of sleep become more frequent. Using task-free fMRI in sleep-deprived participants, the study found that these eye closures are accompanied by widespread co-activation of sensory cortices (visual, auditory, somatosensory) and the default mode network, consistent with internal sensory activity without external input. Co-activation of fronto-parietal attentional areas may reflect resistance to sleep or engagement of mental imagery. These brain activity patterns differed from those during cued eye closures in rested participants and from mind-wandering or light sleep. Eye closures also reduced functional connectivity within the default mode and dorsal attention networks, adding to reductions already caused by sleep deprivation. Thalamic deactivation occurred during eye closures in the sleep-deprived state but similar changes appeared when well-rested.