Heritability of Sleep EEG Topography in Adolescence: Results from a Longitudinal Twin Study

Abstract

The topographic distribution of sleep EEG power is a reflection of brain structure and function. The goal of this study was to examine the degree to which genes contribute to sleep EEG topography during adolescence, a period of brain restructuring and maturation. We recorded high-density sleep EEG in monozygotic (MZ; n = 28) and dizygotic (DZ; n = 22) adolescent twins (mean age = 13.2 ± 1.1 years) at two time points 6 months apart. The topographic distribution of normalized sleep EEG power was examined for the frequency bands delta (1–4.6 Hz) to gamma 2 (34.2–44 Hz) during NREM and REM sleep. We found highest heritability values in the beta band for NREM and REM sleep (0.44 ≤ h2 ≤ 0.57), while environmental factors shared amongst twin siblings accounted for the variance in the delta to sigma bands (0.59 ≤ c2 ≤ 0.83). Given that both genetic and environmental factors are reflected in sleep EEG topography, our results suggest that topography may provide a rich metric by which to understand brain function. Furthermore, the frequency specific parsing of the influence of genetic from environmental factors on topography suggests functionally distinct networks and reveals the mechanisms that shape these networks.

Nature and Nurture: Brain Region-Specific Inheritance of Sleep Neurophysiology in Adolescence

“…Studying the sleeping brain has recently been recognized as a powerful method to understand neural function. Compared with waking measures, which are susceptible to both internal (e.g., attention) and external influences (Kitsune et al, 2015), the sleep EEG offers a stable state that is unaffected by such factors. Over the last decade a functional role of sleep-specific oscillations in sleep-dependent learning, synaptic plasticity, and the recuperative function of sleep have been found (Abel et al, 2013).…”

“…One such oscillation is the sleep spindle: waxing and waning bursts in the sleep EEG between 11 and 16 Hz. Sleep spindles are generated through thalamocortical loops and thus are a valuable and unique marker of the integrity of this system in humans (Huguenard and McCormick, 2007;Andrillon et al, 2011). Deficits in sleep spindles have been reported in many patient populations.…”

“…Slow waves originate in the cortex and propagate by corticocortical and corticothalamocortical connections (Steriade, 2006). Slow waves are locally intensified in a use-dependent manner; if a cortical region is extensively used during the waking day, that region will exhibit greater slow-wave activity (SWA) in the subsequent sleep episode (Huber et al, 2004). Slow waves are hypothesized to be responsible for the recuperative function of sleep, downscaling synapses that are potentiated during the waking day as a result of learning (Tononi and Cirelli, 2006).…”

“…Furthermore, the search for endophenotypes to measure vulnerability to an illness is arguably most fruitful during development given the higher degree of plasticity in adolescence and the higher efficacy of interventions in this developmental phase. Finally, during adolescence the brain undergoes rapid restructuring (Giedd et al, 2015) manifest in the sleep EEG as a steep decline in power (Buchmann et al, 2011). Therefore, findings regarding the heritability of the sleep EEG in adults cannot be generalized to adolescents.…”

Sleep architecture and homeostasis in children with epilepsy: a neurodevelopmental perspective

“…4 There is great variability in the detail of SWA topology between individuals, but findings from night to night in the same individual are remarkably consistent and highly heritable. 33…”