S75 Sleep spindles in humans: From invasive recordings to sexual dimorphism

Abstract

Sleep spindles are episodic bursts of mid-frequency (alpha Bodizs et al., 2009 ). Evidences for prevailing slow spindles and frontofugal modulation of the human anterior thalamic local field potentials, as well as for predominant fast sleep spindling in the parahippocampal gyrus are derived from invasive recordings of epilepsy patients. These new evidences are completed with findings on sleep spindles of healthy subjects indicating sex differences in spindle density (female male), frequency (female > male), hemispheric lateralization (region-specific sex differences), local-global nature (females more global), as well as inter- and intra-hemispheric synchronization (females > males). Some of the sex differences revealed in our studies are depending on age (density, amplitude, and frequency), menstrual cycle phase (oestrogen and progesterone levels → frequency) and contraceptive use (hemispheric laterality). We conclude that slow and fast sleep spindles travel different routes. Moreover, the sexual dimorphism of sleep spindles might reflect the sex differences in neurocognitive architectures. Future studies distinguishing slow-frontal from fast-parietal sleep spindles and considering the sex differences in spindle activity could increase the reproducibility of the findings in the field of sleep-state dependent neural oscillations.