基于fNIRS的情绪对工作记忆负荷影响规律研究

Study on Influence of Emotional State on Work Memory Response Mechanism Using Functional Near-infrared Spectroscopy

目的研究情绪刺激和任务负荷共同影响下的大脑皮层血氧特性响应规律。方法 20名年轻男性分别进行了负性、中性与积极3种情绪图片刺激下1~3-back认知记忆负荷任务实验,采用功能近红外谱(functional near-infrared spectroscopy,fNIRS)监测参试者脑前额叶皮层(prefrontal cortex,PFC)功能区和左右运动区的含氧血红蛋白(Hb O_2)与脱氧血红蛋白(Hbr)信号均值、斜率及近似熵(approximate entropy,ApEn)3种生理特征指标来描述其脑功能活动。结果随着任务负荷增加,均值表征的脑功能活动强度增强,PFC区域血氧供应和脑功能活动强度变化率降低且趋于稳定。近似熵用于表征的脑功能活动复杂度指标,随着任务负荷增加,中性情绪状态下复杂度降低,而在负性和积极情绪状态下复杂度上升。结论背外侧PFC区域为任务负荷敏感区域脑区;运动区域脑功能活动会受情绪状态影响。近似熵能有效地表征脑区fNIRS信号的复杂度变化,并适合描述情绪状态下大脑皮层功能活动多样性。

Objective To explore the mechanism of hemodynamic response in brain cortex during the real com- plex tasks with different emotional stimuli and task loads. Methods Twenty participants were asked to com- plete the work memory tasks under negative picture, positive picture and neutral picture. Three indexes com- puted from fNIRS signal including the mean, the slope and the approximate entropy were used to describe the brain functional activity level in the frontal and motion cortical regions. Results With the increase of the task load, the brain functional activity represented by the mean index increased, while the variation of hemodynam- ic activity, energy supply and functional activities in the prefrontal cortex reduced and then stayed stable. The functional activity describe by ApEn became stronger in positive or negative emotional state when task load en- hanced, while the ApEn changed oppositely in the neutral state when the task load increased. Conclusion The dorsolateral prefrontal cortex is sensitive to task load variation and the motor cortex is affected by the emotional state. ApEn is an effective index for describing the complexity of fNIRS signal and representing the functional activities in the brain cortex influenced by emotional states.