• childhood
• EEG
• fMRI
• NREM sleep
• sleep
• slow waves

EEG slow waves are the main hallmark of NREM sleep. Unraveling the interactions among cortical and subcortical structures associated with their occurrence is crucial for understanding the functional and regulatory mechanisms of NREM sleep. Across the developmental period, slow waves undergo prominent changes in topography and power, but their hemodynamic correlates are largely unknown. A methodological barrier stems from the poor EEG spatial resolution and its incapacity to measure deep subcortical modifications. Also, the potential of emerging multimodal EEG-fMRI recordings, combining the increased temporal resolution of EEG with the high spatial resolution of fMRI, has not been fully exploited in children. To circumvent these issues, we took advantage of previously collected EEG-fMRI recordings from 14 epileptic pediatric patients (age 6-11 y) affected by childhood epilepsy with centrotemporal spikes (CECTS) to investigate cortical and subcortical hemodynamic (BOLD) modifications associated with slow waves during NREM sleep. We found that slow waves are uncorrelated to the occurrence of centrotemporal spikes and linked to BOLD-signal decrease peaking few seconds after the wave onset in the bilateral somatomotor cortex and the insula. We did not measure any significant hemodynamic fluctuations in deep subcortical structures. A qualitative comparison with previously collected data from healthy adults revealed that BOLD-signal changes in children seem to affect slightly more posterior cortical areas, consistent with the established occipitofrontal gradient of slow wave activity (SWA) across development. These findings expand the literature on sleep slow waves in childhood and provide ground for further investigation of their hemodynamic correlates.