Hoshikawa Y, Yamamoto Y
Laboratory for Exercise Physiology and Biomechanics, Graduate School of Education, The University of Tokyo, Japan.
Am J Physiol. 1997 Mar;272(3 Pt 2):H1113-21. doi: 10.1152/ajpheart.1997.272.3.H1113.
The Stroop color-word test (CWT) is a mental stress test involving sensory rejection and has been used as a model of the defense reaction in humans. The present study was designed to investigate effects of CWT on resting cardiac autonomic nervous system activity evaluated by analyses of heart rate (HR) variability (HRV). Eight healthy subjects performed 21 min of CWT after 14 min of resting control followed by 14 min of recovery (RCV). Beat-to-beat R-R intervals (RRI, i.e., HRV), systolic blood pressure (SBP), and instantaneous lung volume were continuously monitored throughout these periods. Steady-state HRV data (10-12 min) for resting control and recovery (12 min) and for 1-11 min (CWT1) and 11-21 min (CWT2) of CWT were analyzed by coarse-graining spectral analysis to break down their total power into harmonic and nonharmonic (fractal) components. The harmonic component was further divided into low (0.0-0.15 Hz, LF)- and high (>0.15 Hz, HF)-frequency components. Cardiac sympathetic (SNS) and parasympathetic (PNS) nervous system activity indicators were evaluated as LF/HF and HF/TP, respectively [LF, HF, and total spectral power (TP) of HRV]. The fractal component had the spectrum of 1/f(beta), and the spectral exponent beta was calculated. RRI decreased and SBP, plasma norepinephrine, and epinephrine concentrations increased significantly (P < 0.05) in response to CWT (CWT1 and CWT2). PNS and SNS indicators did not show any significant (P > 0.05) difference between resting controls and CWT. Whereas the percentage of fractal components in total HRV remained unchanged, beta decreased significantly (P < 0.05) in response to CWT. Transfer magnitudes from SBP to RRI, calculated by cross-spectral analysis, decreased at CWT2. The transfer magnitudes from instantaneous lung volume to RRI were also decreased significantly (P < 0.05) by CWT. It was concluded that although CWT did not affect the SNS indicator of HRV, despite altered HR and vasomotor responses, tonic sympathetic nervous system influence was observed for norepinephrine and epinephrine. In addition, reflex blood pressure (CWT2) and respiratory modulation of HR (CWT1 and CWT2) decreased during CWT. Mental stress altered the fractal nature of HRV (as judged by decreased beta), but mechanism(s) responsible for this change remained unknown.
斯特鲁普颜色-文字测试（CWT）是一种涉及感觉抑制的心理应激测试，已被用作人类防御反应的模型。本研究旨在通过分析心率（HR）变异性（HRV）来研究CWT对静息心脏自主神经系统活动的影响。八名健康受试者在静息对照14分钟后进行21分钟的CWT，随后是14分钟的恢复（RCV）。在整个这些时间段内持续监测逐搏R-R间期（RRI，即HRV）、收缩压（SBP）和瞬时肺容积。通过粗粒化频谱分析对静息对照和恢复（12分钟）以及CWT的1-11分钟（CWT1）和11-21分钟（CWT2）的稳态HRV数据（10-12分钟）进行分析，将其总功率分解为谐波和非谐波（分形）成分。谐波成分进一步分为低频（0.0-0.15 Hz，LF）和高频（>0.15 Hz，HF）成分。心脏交感神经（SNS）和副交感神经（PNS）系统活动指标分别评估为LF/HF和HF/TP [HRV的LF、HF和总频谱功率（TP）]。分形成分具有1/f（β）的频谱，并计算频谱指数β。响应CWT（CWT1和CWT2）时，RRI降低，SBP、血浆去甲肾上腺素和肾上腺素浓度显著升高（P < 0.05）。静息对照和CWT之间，PNS和SNS指标未显示任何显著差异（P > 0.05）。虽然总HRV中分形成分的百分比保持不变，但响应CWT时β显著降低（P < 0.05）。通过互谱分析计算的从SBP到RRI的传递幅度在CWT2时降低。CWT也使从瞬时肺容积到RRI的传递幅度显著降低（P < 0.05）。得出的结论是，尽管CWT不影响HRV的SNS指标，尽管HR和血管运动反应发生了改变，但观察到去甲肾上腺素和肾上腺素存在紧张性交感神经系统影响。此外，在CWT期间，反射性血压（CWT2）和HR的呼吸调节（CWT1和CWT2）降低。心理应激改变了HRV的分形性质（通过降低的β判断），但导致这种变化的机制仍然未知。
