The Prefrontal cortex (PFC) has been highly related to executive functions such as working memory (WM). This study assesses the activity of the PFC in performing the Sternberg WM task (ST) with three levels of difficulty (easy, medium and hard) using the near-infrared spectroscopy (fNIRS) technique. Participants were 43 young and healthy right-handed women. Nine WM task blocks were pseudo randomly presented, three for each difficulty task. The results showed that the participant's performance was better in the easy trials than in the medium and hard trials. Performance in the medium trials was also better than in the hard ones. Bonferroni-corrected paired post-hoc t-tests indicated higher oxygenation in medium and hard tasks than in the easy ones for times between 13 and 42 s in the left lateral PFC and in both, medial and lateral, right PFC. Significant differences in Oxygenated hemoglobin (HbO), Total hemoglobin (HbT) and oxygenation (Oxy) changes depending on the Sternberg WM task were found. Unlike previous studies with fNIRS and WM, the current study uses a highly controlled WM task that differentiates between encoding, retention and retrieval phases, comparing different levels of task load.

前额叶皮层 (PFC) 与工作记忆 (WM) 等执行功能高度相关。本研究使用近红外光谱 (fNIRS) 技术评估 PFC 在执行 Sternberg WM 任务 (ST) 的三个难度级别（简单、中等和困难）时的活动。参与者是 43 名年轻健康的右手女性。九个 WM 任务块是伪随机呈现的，每个难度任务三个。结果表明，参与者在简单试验中的表现优于在中等和困难试验中的表现。在中等试验中的表现也优于在困难试验中。Bonferroni 校正的成对事后 t 检验表明，在左侧 PFC 以及内侧和外侧、右侧 PFC 的 13 至 42 秒内，中等和困难任务中的氧合高于简单任务。发现氧合血红蛋白 (HbO)、总血红蛋白 (HbT) 和氧合 (Oxy) 变化取决于 Sternberg WM 任务的显着差异。与之前使用 fNIRS 和 WM 的研究不同，当前的研究使用高度受控的 WM 任务，区分编码、保留和检索阶段，比较不同级别的任务负载。