EEG-derived spectral processing and the development of working memory through adolescence

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ABSTRACT
Adolescence is characterized by neurodevelopmental specialization that impacts cognition and decision-making. Simultaneously, changes in the inhibitory (Gamma-Aminobutyric Acid, GABA) and excitatory (glutamate) signaling mechanisms in prefrontal cortex suggest changes in excitatory/inhibitory (E/I) balance which may contribute to developmental changes in cortical signal processing and, consequently, cognitive behaviors. The interplay of GABA and glutamate signaling plays a role in the generation of high frequency oscillations measured through electroencephalogram (EEG). Using EEG, we investigated age-related changes in the gamma (30-70 Hz), beta (15-30 Hz), theta (4-7 Hz) and alpha (8-12 Hz) frequency bands during the delay period of a memory-guided saccade (MGS) task in 148 10-30-year olds. A linear mixed-effects model and a support vector regression (SVR) were utilized to determine associations between EEG activity (power, event duration, number of events, and trial-by-trial variability), behavior, and age. We found significant age-related decreases for spectral events in the gamma and beta bands and increases in the alpha band. The SVR-machine learning approach found that the delay period measures were more highly predictive of age than the fixation measures. Trial-to-trial variability in EEG activity decreased with age, consistent with decreases in performance variability. Gamma and beta band activity showed significant associations with MGS performance, with increases in these measures corresponding to increases in performance. Together, these data suggest that spectral events in high frequency bands, such as gamma and beta, may be indicative of developmental maturation of cognitive control underlined by maturational changes in GABA/glutamate function. Next steps will investigate associations between EEG findings and MRS evidence of age related changes in GABA and glutamate.