Working memory-related neural activity varies with task load, and these neural variations can be constrained by working memory capacity (WMC). For instance, some studies suggest that parietal and frontal P300 amplitudes, reflecting working memory functioning, vary differentially with task load and WMC. The present study explored whether the predominance of parietal over frontal P300 amplitude is related to WMC, and whether this relationship varies according to task load. Thirty-one adults aged 20–40 years performed a Sternberg task with two set sizes (2 vs. 6 items), during which event-related potentials were recorded. This allowed us to explore the P300 and estimate the magnitude of its parietal over frontal predominance, calculated as a parietal over frontal predominance index (PFPI). Participants also performed the Digit Span and alpha span tests, which were used to compute an independent index of WMC. Results revealed the classic parietal over frontal P300 predominance. They also indicated that the PFPI decreased as task load increased, owing mainly to an increase in frontal P300 amplitude. Interestingly, WMC was positively correlated with the PFPI, suggesting that individuals with greater WMC exhibited greater parietal over frontal predominance. These correlations did not vary across set sizes. Parietal over frontal predominance was reduced in individuals with lower WMC, who relied more on frontal neural resources. This frontal upregulation may have reflected the recruitment of supplementary attentional executive operations to compensate for less efficient working memory maintenance operations.

工作记忆相关的神经活动随着任务负载的不同而变化，并且这些神经变化可能受到工作记忆容量（WMC）的限制。例如，一些研究表明，反映工作记忆功能的顶叶和额叶 P300 振幅随任务负荷和 WMC 的变化而存在差异。本研究探讨了顶叶 P300 振幅相对于额叶 P300 振幅的优势是否与 WMC 相关，以及这种关系是否根据任务负荷而变化。31 名 20-40 岁的成年人执行了具有两种规模（2 项与 6 项）的 Sternberg 任务，在此期间记录了事件相关电位。这使我们能够探索 P300 并估计其顶叶相对额叶优势的大小，计算为顶叶相对额叶优势指数 (PFP​​I)。参与者还进行了数字跨度和阿尔法跨度测试，用于计算 WMC 的独立指数。结果显示，经典的顶叶 P300 优势优于额叶 P300。他们还指出，随着任务负荷的增加，PFPI 下降，这主要是由于额叶 P300 幅度的增加。有趣的是，WMC 与 PFPI 呈正相关，这表明 WMC 较大的个体表现出顶叶优势大于额叶优势。这些相关性在集合大小之间没有变化。在 WMC 较低的个体中，顶叶相对额叶的优势减弱，他们更依赖额叶神经资源。这种额叶上调可能反映了补充性注意力执行操作的招募，以补偿效率较低的工作记忆维护操作。