Data_Sheet_2_Vagal Flexibility Mediates the Association Between Resting Vagal Activity and Cognitive Performance Stability Across Varying Socioemotional Demands.docx

Vagal flexibility describes the ability to modulate cardiac vagal responses to fit a dynamic range of challenges. Extant theory on vagal function implies that vagal flexibility is a mediating mechanism through which resting vagal activity, a putative individual difference related to self-regulation, affects adaptive behavior and cognition. Nevertheless, little research has directly tested this hypothesis, thereby leaving fundamental mechanisms of vagal function and adaptability unclear. To this end, 47 healthy subjects completed a 5 min baseline followed by Stroop tasks combined with concurrent auditory distractors. There were four different Stroop task conditions that varied the social and emotional content of the auditory distractors. Electrocardiogram was continuously recorded to assess vagal responses to each condition as heart rate variability [root mean square of successive differences (RMSSDs)] reactivity. Vagal flexibility significantly mediated the association between resting vagal activity and stability of inhibition performance (Stroop interference) scores. In particular, higher resting RMSSD was related to higher standard deviation of RMSSD reactivity scores, reflecting greater differences in RMSSD reactivity between distractor conditions (i.e., greater vagal flexibility). Greater vagal flexibility was in turn related to more stability in Stroop interference across the same conditions. The mean of RMSSD reactivity scores across conditions was not significantly related to resting RMSSD or stability in Stroop performance, and mean RMSSD reactivity did not mediate relations between resting RMSSD and stability in Stroop performance. Overall, findings suggest that vagal flexibility may promote the effects of resting vagal activity on stabilizing cognitive inhibition in the face of environmental perturbations.

迷走神经灵活性（vagal flexibility）指个体调节心脏迷走神经反应以适配动态挑战范围的能力。现有迷走神经功能理论指出，迷走神经灵活性是一类中介机制：静息迷走神经活动（resting vagal activity）作为一种与自我调节相关的推定个体差异指标，可通过该机制影响适应性行为与认知表现。然而，目前鲜有研究直接验证这一假说，致使迷走神经功能与适应性的核心机制仍有待阐明。为此，47名健康受试者完成了5分钟的静息基线记录，随后完成了同步搭载听觉干扰刺激的斯特鲁普任务（Stroop tasks）。实验设置了四种不同的任务条件，其差异在于听觉干扰刺激所携带的社会与情感内容。研究持续采集受试者的心电图（electrocardiogram, ECG），以心率变异性（heart rate variability）中的逐次差值均方根（root mean square of successive differences, RMSSD）反应性指标，评估各任务条件下的迷走神经反应。分析结果表明，迷走神经灵活性显著中介了静息迷走神经活动与抑制表现稳定性（即斯特鲁普干扰效应得分）之间的关联。具体而言，更高的静息RMSSD水平与RMSSD反应性得分的标准差呈正相关，这反映出不同干扰刺激条件下的RMSSD反应性差异更大，即迷走神经灵活性更强。反之，更强的迷走神经灵活性与同一任务序列中斯特鲁普干扰效应的稳定性更高显著相关。各任务条件下RMSSD反应性得分的平均值，与静息RMSSD水平、斯特鲁普表现稳定性均无显著关联；且平均RMSSD反应性也未中介静息RMSSD与斯特鲁普表现稳定性之间的关系。总体而言，本研究结果提示，迷走神经灵活性或可强化静息迷走神经活动在应对环境扰动时对认知抑制稳定性的增益作用。