Our recent review of the

Our recent review of the literature revealed only two studies that evaluated coherence in ASD in the sleeping brain, and together, the studies included more adults than children. In 2010, Leveille et al. (Leveille et al., 2010) compared coherence during REM sleep between nine adults with ASD and 13 typically developing adults. The authors found no differences in interhemispheric coherence patterns, however, they did show increased intrahemispheric coherence in the left visual cortex involving both short- and long-range connections and reductions in coherence in the right frontal lobe. In contrast, a 2010 study by Lazar et al. (Lazar et al., 2010) recorded 18 children and young adults with Asperger\'s disorder and normal IQ and compared them to 13 children and young adults without ASD or intellectual disability in non-REM sleep. As Leveille\'s group did, this study also reported no difference in interhemispheric coherence patterns, but reported a comparative reduction in intrahemispheric coherence patterns in the right, fronto-central area in those with ASD. These are very small studies and direct comparison is made difficult by the differences in the presence or absence of intellectual disabilities and in sleep states examined. Functional connectivity may vary with age and therefore, any evaluation of Sunitinib Malate activity patterns as potential biomarkers must be mindful that the developmental timing of the evaluation is likely a critical factor in the interpretation of differences. Although there have been a few small, longitudinal EEG studies in typical children (Kurth et al., 2013; Tarokh et al., 2014) reporting region-specific increases in sleep coherence across development, there are no longitudinal ASD coherence studies for comparison. Such evaluations would inform on developmental trajectories and perhaps provide insight into the timing for optimal intervention. We do not comment on age-related changes in coherence or phase lag in this cross-sectional study, as our forthcoming report on the longitudinal data from this sample will better address this question. The evaluation of coherence during sleep as a valuable and informative exercise is undeniable. The sleep EEG not only reflects the maturation of the brain (Kurth et al., 2013) but also allows for examination of dynamic neural networks in the absence of external stimuli. In addition, new insight into the function of sleep states makes it imperative that we not overlook the brain\'s activity during sleep in neurodevelopmental disorders. While the exact function of sleep is unknown, the strongest evidence from human and animal experimental studies suggests that sleep\'s major role is to regulate brain plasticity (Wang et al., 2011). SWS is implicated in learning and memory throughout the lifespan and a prevailing hypothesis has been that SWS is essential for the consolidation of memories temporarily laid down during waking hours. However, recent work on REM dependent neuroplasticity in the cat visual cortex (Dumoulin et al., 2015) suggests a similar role for REM sleep in the proper maturation of the sensory cortices in the developing brain. Given that there are both age- and state-dependent differential effects of sleep on neuronal responses and processes, further evaluation of sleep coherence during critical windows of neuromaturation is clearly important to our understanding of neurodevelopmental disorders. Finally, we note that children with autism are frequently reported to have epileptiform activity, in the form of spikes, sharp waves, and spike-and-wave discharges on their EEG (Hashimoto et al., 2001; Hughes and Melyn, 2005; Parmeggiani et al., 2007; Spence and Schneider, 2009). In this study, the rate of epileptiform activity was low. The low incidence of epileptiform activity in the ASD group suggests that it was not a contributing factor in our findings.
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