Abstract
Working memory (WM) is the ability to temporarily store and manipulate information. This cognitive function is critical for other complex behaviors such as reasoning, comprehension, and problem-solving. While behavioral improvements are well-documented, the underlying neural mechanisms of WM development, particularly that which is related to neural oscillations, is understudied and warrants further investigation. This study aimed to characterize the developmental trajectory of neural oscillatory activity, specifically within the alpha-beta frequency range (~8-18 Hz), that supports WM encoding and maintenance processes in children and adolescents. This study also aimed to understand how the development of WM-related oscillatory dynamics is related to cognition in a broader context. Magnetoencephalography (MEG) was utilized to record neural activity from 74 participants aged 7-15 years (61 participants included in final analysis) during a letter-based Sternberg WM paradigm; participants also completed a neuropsychological assessment battery. The primary hypothesis was that older participants would exhibit stronger decreases in alpha-beta power (i.e., stronger event-related desynchronizations [ERDs]) than their younger counterparts and that these developmental alterations would be predictive of cognitive abilities, both verbal and nonverbal. Our results revealed significant age-related changes following this pattern during both the encoding and maintenance phase. Encoding-specific power differences were revealed to be robust and widespread, and were broken down into two factors, which were hypothesized to represent domain-general and domain-specific WM systems. These encoding factors were ultimately predictive of the age-related improvement expected in verbal and nonverbal cognitive abilities. The current findings suggest that the maturation of verbal WM relies heavily on the development of encoding processes.