Cognitive Science Research Group, HAS-Budapest Technical University, Hungarian Academy of Science, Budapest, Hungary
*Correspondence: Róbert Bódizs, Cognitive Science Research Group, HAS-Budapest Technical University, Hungarian Academy of Sciences, Budapest, Hungary.

Alterations in macro- and microstructural characteristics of sleep are emerging features of several developmental disabilities, but quantitative EEG data on the sleep phenotype of adolescents and young adults with Williams Syndrome (WS, a genetically determined developmental disorder linked to a microdeletion in chromosome 7q11.23 and associated with mild to moderate mental retardation and with a distinctive cognitive-linguistic profile) is still lacking. Here we report WS-specific features of patterns of antero-posterior 8–16 Hz EEG power distributions during NREM sleep, which were formerly shown to be stable in time, resistant to experimental perturbations and characterized by strong genetic determination in adult volunteers. Subjects were 9 WS and 9 controls (C) matched for age and sex, sleeping for two consecutive nights in the laboratory. Analyses included group comparisons of raw and z-transformed power spectra, as well as the analysis of sleep spindling by the individual adjustment method. WS subjects were characterized by a region-independent decrease in high alpha/low sigma (10.50–12.50 Hz) and a central increase in high sigma (14.75–15.75 Hz) raw EEG power. Z-scores were characterized by decreased 10.25–12.25 Hz values and increased 14–16 Hz values in a region-independent manner, but with maximal effects at the fronto-centro-parietal derivations surrounding the vertex. Fast sleep spindling and the antero-posterior differences in power distributions occurred at higher frequencies in WS than in C subjects, the differences averaging a 1 Hz shift. These data suggest a redistribution of the 8–16 Hz EEG power toward the higher frequencies and/or a higher frequency of NREM sleep thalamocortical oscillatory activity in WS. This affords the possibility of analyzing the genetic bases of thalamocortical dynamics in humans and other mammals.

Supported by the National Research Fund of Hungary (OTKA NF60806 to I.K.).