Prete Z D, Grigg P
Department of Mechanical and Aeronautical Engineering, University of Rome la Sapienza, 00184 Rome, Italy.
J Neurophysiol. 1998 Aug;80(2):745-54. doi: 10.1152/jn.1998.80.2.745.
Twenty-four rapidly adapting (RA) cutaneous afferents were recorded from a preparation of isolated, innervated hairy skin from the rat hindlimb for the purpose of identifying the mechanical variables associated with the initiation of afferent discharge. Neurons were studied while the skin was stretched dynamically along a single direction with the use of a linear actuator and a feedback controller. Input signals were load- or displacement-controlled stretches that followed either periodic or pseudorandom Gaussian noise control signals. When the tissue was actuated, loads and displacements were measured along the direction of stretch and neuronal responses were recorded. All RA afferents were activated by dynamic stretching. None had a sustained response to static stretch. Cross-correlation products, calculated between neuronal responses and either stress- or strain-related variables observed at the time of the spike, revealed a strong relationship between neuronal responses and tensile stress. Neuronal responses were observed at rates of change of stress between +1,000 and -800 kPa/s. Neuronal responses were poorly related to skin strain. Two loading conditions were used along the direction transverse to the stretch. In one condition the sides were unconstrained, so that on axial loading there was zero stress and negative strain along the transverse axis. In the other condition the sides were constrained so that when the tissue was loaded axially there was zero strain and positive stress along the transverse axis. In these two conditions the same level of axial stress was associated with two levels of axial strain. The neuronal responses were determined by the stress and not the strain. Neuronal responses were observed at stresses >5 kPa. It appears that RA afferents make little contribution to signaling limb movements or position in rat hindlimb on the basis of the behavior of rat hindlimb skin, as observed when the limb is rotated.
从大鼠后肢分离的、有神经支配的多毛皮肤制备物中记录了24条快速适应性（RA）皮肤传入神经，目的是确定与传入放电起始相关的力学变量。在使用线性致动器和反馈控制器使皮肤沿单一方向动态拉伸时，对神经元进行了研究。输入信号是跟随周期性或伪随机高斯噪声控制信号的负载控制或位移控制拉伸。当组织被驱动时，沿拉伸方向测量负载和位移，并记录神经元反应。所有RA传入神经均由动态拉伸激活。没有一个对静态拉伸有持续反应。在神经元反应与尖峰时刻观察到的应力或应变相关变量之间计算的互相关积，揭示了神经元反应与拉应力之间的强关系。在应力变化率为+1000至-800 kPa/s时观察到神经元反应。神经元反应与皮肤应变的相关性很差。沿与拉伸方向垂直的方向使用了两种加载条件。在一种条件下，侧面不受约束，因此在轴向加载时，横向轴上的应力为零且应变呈负向。在另一种条件下，侧面受到约束，因此当组织轴向加载时，横向轴上的应变零且应力为正向。在这两种条件下，相同水平的轴向应力与两种水平的轴向应变相关。神经元反应由应力而非应变决定。在应力>5 kPa时观察到神经元反应。根据大鼠后肢旋转时观察到的大鼠后肢皮肤行为，RA传入神经似乎对大鼠后肢肢体运动或位置的信号传递贡献很小。
