PhD Scientific Days 2023

Mental Health Sciences I.

Maturation of sleep spindles in typically developing adolescents as revealed by HD-EEG

Text of the abstract

Introduction:
Adolescence is a sensitive period when the human brain is prone to hormonal changes and environmental stressors. Sleep also changes substantially reflecting prominent cortical developmental trajectories that can be captured by electroencephalography. Sleep spindles may be hallmarks of adolescent development signaling distinct stages of brain maturation.

Aims:
In this study, we aimed to investigate if there are differences between the developmental trajectories of the frontally dominant slow and the centro-parietally dominant fast sleep spindles between the three adolescent age-groups. Further, we looked at potential sex differences in the maturational process reflected in sleep spindle characteristics.

Methods:
Our research group recorded full-night HD-EEG data from sixty healthy individuals in their adolescence. We analysed sleep spindle parameters of the frequency range 11–16 Hz being developmentally relevant cortical oscillatory patterns. We broke down the period of adolescence into age-groups 12, 16 and 20, and differentiated between slow and fast sleep spindles. Considering individual differences and variations in sleep spindle parameters we applied the Individual Adjustment Method based on the average amplitude spectrum of NREM sleep in determining peak frequencies derived from the Center of Gravity (CoG).

Results:
Our analyses reveal that both slow and fast spindle maximum amplitude decline significantly with age. We also confirm such a decline for duration in the case of slow spindles but not fast spindles. Spindle density requires further investigation to reach a meaningful conclusion regarding its development. Both slow and fast spindle frequency CoG increases throughout the entire age-range. We observed sex difference in the age-group of 20 for both slow and fast sleep spindle frequencies to be higher in females.

Conclusions:
We found a difference between the development of slow and fast spindles with respect to duration, amplitude, and frequency. The narrow age-ranges enable us to conclude that in terms of spindle amplitude and duration most of the developmental changes take place by the age of 16.

Funding:
This research was supported by the Hungarian National Research, Development and Innovation Office
grants NK-104481 and K-134370 to I.K.

Gabor Bocskai
gbocskai@gmail.com
Semmelweis University, Doctoral School of Mental Health Sciences.
Supervisor: Dr. Ilona Kovács