Data from: The avalanche-like behaviour of large-scale haemodynamic activity from wakefulness to deep sleep
Bocaccio, Hernán et al. (2019), Data from: The avalanche-like behaviour of large-scale haemodynamic activity from wakefulness to deep sleep, Dryad, Dataset, https://doi.org/10.5061/dryad.78v68ss
Increasing evidence suggests that conscious awareness is supported by critical or near-critical cortical dynamics, which exhibit scale-free cascades of spatiotemporal activity. These avalanches of neural origin have been detected at multiple scales, from in vitro and in vivo microcircuits to voltage imaging and brain-wide functional magnetic resonance imaging (fMRI) recordings. Criticality endows the cortex with information processing capacities postulated as necessary for consciousness, yet it remains unknown how reduced awareness impacts on the avalanche-like behaviour of large-scale human hemodynamic activity. We observed a scale-free hierarchy of co-activated connected clusters by applying a point-process transformation to fMRI data recorded during wakefulness and non-rapid eye movement (NREM) sleep. Maximum likelihood estimates revealed a significant effect of sleep stage on the scaling parameters of the cluster size power-law distributions. Post-hoc statistical tests showed that differences were maximal between wakefulness and N2 sleep. These results were robust against spatial coarse-graining and different point-process thresholds, and disappeared upon phase-shuffling the fMRI time series. The onset of evoked neural bistabilities that prevent arousals during N2 sleep do not suffice to explain these differences, which point towards changes in the intrinsic dynamics of the brain that are necessary to consolidate a state of deep sleep.