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Brain development is characterized by maturational processes that span the period from childhood through adolescence to adulthood, but little is known whether and how developmental processes differ during these phases. We analyzed the development of functional networks by measuring neural synchrony in EEG recordings during a Gestalt perception task in 68 participants ranging in age from 6 to 21 years. Until early adolescence, developmental improvements in cognitive performance were accompanied by increases in neural synchrony. This developmental phase was followed by an unexpected decrease in neural synchrony that occurred during late adolescence and was associated with reduced performance. After this period of destabilization, we observed a reorganization of synchronization patterns that was accompanied by pronounced increases in gammaband power and in theta and beta phase synchrony. These findings provide evidence for the relationship between neural synchrony and late brain development that has important implications for the understanding of adolescence as a critical period of brain maturation.oscillations ͉ synchrony ͉ adolescence ͉ electroencephalography ͉ Gestalt perception D evelopmental psychology and brain research has focused mainly on the early pre-and postnatal periods as critical windows for the organization and functional adjustment of neural circuitry. These studies revealed the important role of early experience in shaping cortical networks and emphasized the decline of neuronal plasticity with age. However, more recent evidence suggests that brain development and its susceptibility to epigenetic influences extends far beyond the early postnatal stages and in humans comes to an end only around age 20.Emerging evidence from anatomy and physiology suggests that later developmental periods, such as adolescence, may have a crucial impact on the organization of cortical circuitry. Anatomically, the volume and organization of white matter increases continuously (1-3), whereas the volume of cortical gray matter increases only until the onset of adolescence and then decreases again (4-6). Physiologically, there is evidence that dopamine-NMDA receptor interactions in prefrontal cortex (7) mature only after adolescence, and there are data suggesting late maturation of GABAergic neurotransmission (8).These findings indicate important changes in anatomical and physiological parameters during late developmental periods, but the functional implications of these changes are poorly understood. The putative relevance of these changes is highlighted by the fact that the onset of brain disorders, such as schizophrenia, that cause lasting emotional and cognitive dysfunctions often occurs during the transition from adolescence to adulthood (9). Thus, not only the early but also the late maturational processes are likely to be critical, especially for the development of higher cognitive functions.We investigated the development of functional networks by examining age-dependent changes in task-related neural oscillation...

Previous studies in electrophysiology have provided consistent evidence for a relationship between neural oscillations in different frequency bands and the maintenance of information in working memory (WM). While the amplitude and cross-frequency coupling of neural oscillations have been shown to be modulated by the number of items retained during WM, interareal phase synchronization has been associated with the integration of distributed activity during WM maintenance. Together, these findings provided important insights into the oscillatory dynamics of cortical networks during WM. However, little is known about the cortical regions and frequencies that underlie the specific maintenance of behaviorally relevant information in WM. In the current study, we addressed this question with magnetoencephalography and a delayed match-to-sample task involving distractors in 25 human participants. Using spectral analysis and beamforming, we found a WM load-related increase in the gamma band (60 -80 Hz) that was localized to the right intraparietal lobule and left Brodmann area 9 (BA9). WM-load related changes were also detected at alpha frequencies (10 -14 Hz) in Brodmann area 6, but did not covary with the number of relevant WM-items. Finally, we decoded gamma-band source activity with a linear discriminant analysis and found that gamma-band activity in left BA9 predicted the number of target items maintained in WM. While the present data show that WM maintenance involves activity in the alpha and gamma band, our results highlight the specific contribution of gamma band delay activity in prefrontal cortex for the maintenance of behaviorally relevant items.