Department of Cognitive and Neural Systems, Boston University, Boston, MA, USA.
Physiol Meas. 2010 Jun;31(6):857-73. doi: 10.1088/0967-3334/31/6/009. Epub 2010 May 21.
The state-dependent portion of cardio-vagal baroreflex control is called baroreflex hyteresis: we observe hysteresis when RR interval and carotid diameter depend on both the direction and value of arterial pressure. The elasticity of arterial walls, as well as the responsiveness of central command reset controls the real-time pattern of neural outflow, which is indirectly measured by RR interval in humans. We model the state-dependent relationship among pressure, vessel diameter and heart rate as a three-dimensional planar ellipse. Two-dimensional projections of this ellipse provide motion direction and quantify hysteresis between mechanical (pressure-diameter), neural (diameter-heart rate), and integrated baroreflex (pressure-heart rate) components. A convenient measure for the magnitude of hysteresis is the ratio of the semi-minor and semi-major axes of the best fitting ellipse. This ratio is given a sign according to the direction of its motion. The signed sum of the hysteresis ratio for vessel mechanics and central neural control reliably predicts cardio-vagal hysteresis. Using this relationship, we can quantify the relative importance of neural versus mechanical contributions to integrated baroreflex responses.
心-迷走神经血压反射的状态依赖部分称为血压反射滞后：当 RR 间期和颈动脉直径既依赖于动脉血压的方向又依赖于动脉血压的值时，我们观察到滞后现象。动脉壁的弹性以及中枢命令重置控制的反应性控制着神经输出的实时模式，这在人类中通过 RR 间期间接测量。我们将压力、血管直径和心率之间的状态依赖关系建模为一个三维平面椭圆。该椭圆的二维投影提供运动方向，并量化机械（压力-直径）、神经（直径-心率）和综合血压反射（压力-心率）成分之间的滞后。滞后幅度的一个方便度量是最佳拟合椭圆的半轴的半长轴比。根据其运动方向，该比率被赋予一个符号。血管力学和中枢神经控制的滞后比的符号和可靠地预测心迷走神经滞后。使用这种关系，我们可以量化神经对综合血压反射反应的贡献与机械贡献的相对重要性。
