An event-related potential study of working memory in children

To examine the neural mechanisms o working memory in children, event-related potentials (ERPs) were recorded from the 12―13 year-old while they performed a delayed match-to-sample task. The ERP results revealed that new and studied objects both evoked a late positive ERP componen peaking around 350 ms during the working memory process. New objects evoke a more positive ERP waveform than the studied objects. The scalp distri bution showed that the frontal-central electrode sites were associated with object working memory proc esses. When tracking new or studied targets among visual distracters, ERPs of targets and distracters revealed differential responses as early as 150 ms The visual targets evoked larger and more positive ERP responses than the distracters. The typica old-new effect was observed between ERPs of stud ied and new distracters. However, ERPs of new and studied targets differed at about 250 ms, in which new targets evoked more positive-going and slightly earlier ERP responses. In addition, a P3a componen was found for new targets only, and was absent in ERPs of studied targets at frontal and central sites The present study results reveal the spatial and temporal characteristics of neural mechanisms un derlying working memory in children, some of which are distinct from those in adults.