Sexual Dimorphism of Social-Emotional Development in Toddlers
Objectives: To identify associations between electrocortical spectral power during infant natural sleep and subsequent social-emotional development in toddlers.
Methods: Participants included in the present analysis consisted of infants initially enrolled in the Safe Passage Study with follow-up assessments currently underway. The sample consisted of 203 infants (116 males/87 females; gestational age at birth M: 39.4 weeks, SD: 1.1 weeks) from the Western Cape Province of South Africa who had both neonatal EEG and developmental assessments at ~3 years of age. Neonatal EEG was recorded during sleep in the supine position using EGI’s (GEM) 28-lead net for approximately thirty minutes. Average electrocortical power was computed in 10 frequency bands (Delta 1-3 Hz; Theta 4-6 & 7-9 Hz; Alpha: 10-12 Hz, Beta: 13-15, 16-18, & 19-21 Hz, Low-Gamma: 22-24 & 25-36 Hz, Gamma: 37-48 Hz) and 12 brain regions (left and right: frontal-polar, frontal, central, parietal, temporal, & occipital) separately within active (REM) and quiet (slow wave) sleep. The Brief Infant-Toddler Social and Emotional Assessment (BITSEA) was administered at 3 years of age (M: 37.0 months, SD: 2.6 months). Multiple regressions were run to predict social-emotional development from neonatal EEG power with prenatal exposures, gestational age at birth, and hours of life as covariates. Secondary sex specific analyses were also computed.
Results: In active sleep, increased Alpha, Beta, and Low-Gamma EEG power in the left temporal, right temporal, and left-frontal regions were associated with increased socioemotional problems on the BITSEA, (F(1, 196) = 2.33 - 2.92, p’s = .000 - .01. Sex specific analyses revealed increased Delta, Theta, and Alpha EEG power during quiet sleep in the left temporal, frontal, and frontal polar regions were associated with increased socioemotional problems in males only, (F(1, 111) = 4.49 – 6.37, p’s = .000 - .01. Conversely for females, increased Delta, Theta, and Alpha EEG power in the right frontal and central regions were associated with increased socioemotional competence scores, (F(1, 82) = 1.18, p’s = .000 - .01 (Figure 1).