Home Research Research Highlights
Brain waves during sleep in human infants are differentially associated with measures of language development in boys and girls


Sleep brain wave activity in 6½ month-old girls is positively correlated with expressive language measures, while in boys, similar activity is negatively correlated with receptive language measures. These differences may be related to sleep spindle bursts that first appear during “mini-puberty”, at 8 weeks of age, when there is a burst of hormones in the brain. Temporal Dynamics of Learning Center researchers, Drs. Sue Peters and April Benasich, at the Center for Molecular and Behavioral Neuroscience, Rutgers University-Newark, have shown that brain rhythms in the sleep spindle range, differ between boys and girls, this difference is prominent on the left side of the brain, and is associated with language measures. At 6½ months, the strength of slower activity was positively correlated with expressive language in females, whereas the strength of faster activity was negatively correlated with receptive language in males. This data suggests that early language-based neural network development is associated with the frequency and layout of spindles in the brain, and that these differences in infant sleep spindles may contribute to sex differences in neural processing of language..


Leanne Chukoskie

 

Impact/Benefit:
Infant sleep spindles may comprise a sensitive measure of individual differences in brain network development, thus contributing to group-level sex differences in neural processing of language. During this time, infants are developing pre-linguistic auditory cortical maps that support emerging language. Mini-puberty, a burst of gonadal hormones that occurs at about 8 weeks-of-age, concurrent with spindle onset, may well impact later language development.

Background/Explanation:
The topography of spectral power in the spindle frequency range (10-16Hz) during daytime naps was mapped in typically developing infants, aged 3.5-4 and 6.5-7 months. Concurrent behavioral assessments allowed examination of sex-based differences between topographical spindle spectral power and its association to standardized measures of behavior and cognition. Sleep spindles are patterned bursts of oscillatory brain activity, visible in the scalp EEG, associated with NREM sleep, neuroplasticity and cortical development. In infants, spindles are a biomarker of maturation, first appearing about 4-9 weeks of age, reaching peak duration and density between 3 and 6 months-of-age. During this time, infants are developing pre-linguistic auditory cortical maps that support emerging language. Spindle-specific sex differences in infants have not been previously examined.

From: Peters, S.E. and Benasich, A.A. (submitted, 2017). Sleep spindle topography in 6.5 month-old human infants is sexually dimorphic, correlated with language measures, and functionally left-lateralized.