The n-back task is one of the most commonly used working memory (WM) paradigms in cognitive neuroscience. Converging evidence suggests activation in the lateral prefrontal cortex (PFC) and pupil dilation [a proxy for locus coeruleus (LC) activation] during this task. However, it remains unclear whether the lateral PFC and the LC are functionally associated during n-back task performance. This study's aim was to examine the relationship between changes in lateral PFC activity and the pupil diameter and to evaluate the effect of WM load on such relationship during the n-back task. Thirty-nine healthy young adults (10 males, 29 females) underwent a number n-back paradigm with 0- and 3-back conditions. Their prefrontal hemodynamics and changes in pupil size during task performance were simultaneously measured using a 16-channel functional near-infrared spectroscopy (fNIRS) device and a wearable eye tracker. Young adults exhibited significant activation in the bilateral lateral PFC and significant increases in pupil size when the WM load was high (i.e., 3-back) but not low (i.e., 0-back) compared with the resting period. Interestingly, significant positive correlations were found between changes in lateral PFC activity and pupil size during the 0-back task only. These correlations tended to be stronger during the 0-back than the 3-back condition. Thus, the functional relationship between the lateral PFC and the LC may vary at different load levels during the n-back task. Our findings have important implications for neuropsychiatric research and support concurrent fNIRS and pupillometric measurements for a better understanding of the mechanisms underlying WM processing.

该ñ -back任务是在认知神经科学中最常用的工作记忆（WM）范式之一。汇聚证据表明，在此任务期间，外侧前额叶皮层 (PFC) 和瞳孔扩张 [蓝斑 (LC) 激活的代理] 中的激活。然而，尚不清楚横向 PFC 和 LC 在n- back 任务执行期间是否在功能上相关。本研究的目的是检查横向 PFC 活动的变化与瞳孔直径之间的关系，并评估 WM 负荷在n- back 任务期间对这种关系的影响。39 名健康的年轻人（10 名男性，29 名女性）接受了n-back 范式与 0- 和 3-back 条件。使用 16 通道功能近红外光谱 (fNIRS) 设备和可穿戴眼动仪同时测量他们的前额叶血流动力学和任务执行期间瞳孔大小的变化。与静息期相比，当 WM 负荷高（即 3-back）但不低（即 0-back）时，年轻人的双侧 PFC 显着激活，瞳孔大小显着增加。有趣的是，仅在 0-back 任务期间，横向 PFC 活动的变化与瞳孔大小之间存在显着的正相关。这些相关性在 0-back 期间往往比 3-back 条件更强。因此，横向 PFC 和 LC 之间的函数关系可能会在n-回任务。我们的研究结果对神经精神病学研究具有重要意义，并支持同时进行 fNIRS 和瞳孔测量，以更好地理解 WM 处理的机制。