Deliagina T G, Beloozerova I N, Zelenin P V, Orlovsky G N
Department of Neuroscience, Karolinska Institute, SE-17177, Stockholm, Sweden.
Brain Res Rev. 2008 Jan;57(1):212-21. doi: 10.1016/j.brainresrev.2007.06.017. Epub 2007 Jul 27.
Different species maintain a particular body orientation in space (upright in humans, dorsal-side-up in quadrupeds, fish and lamprey) due to the activity of a closed-loop postural control system. We will discuss operation of spinal and supraspinal postural networks studied in a lower vertebrate (lamprey) and in two mammals (rabbit and cat). In the lamprey, the postural control system is driven by vestibular input. The key role in the postural network belongs to the reticulospinal (RS) neurons. Due to vestibular input, deviation from the stabilized body orientation in any (roll, pitch, yaw) plane leads to generation of RS commands, which are sent to the spinal cord and cause postural correction. For each of the planes, there are two groups of RS neurons responding to rotation in the opposite directions; they cause a turn opposite to the initial one. The command transmitted by an individual RS neuron causes the motor response, which contributes to the correction of posture. In each plane, the postural system stabilizes the orientation at which the antagonistic vestibular reflexes compensate for each other. Thus, in lamprey the supraspinal networks play a crucial role in stabilization of body orientation, and the function of the spinal networks is transformation of supraspinal commands into the motor pattern of postural corrections. In terrestrial quadrupeds, the postural system stabilizing the trunk orientation in the transversal plane was analyzed. It consists of two relatively independent sub-systems stabilizing orientation of the anterior and posterior parts of the trunk. They are driven by somatosensory input from limb mechanoreceptors. Each sub-system consists of two closed-loop mechanisms - spinal and spino-supraspinal. Operation of the supraspinal networks was studied by recording the posture-related activity of corticospinal neurons. The postural capacity of spinal networks was evaluated in animals with lesions to the spinal cord. Relative contribution of spinal and supraspinal mechanisms to the stabilization of trunk orientation is discussed.
由于闭环姿势控制系统的活动，不同物种在空间中保持特定的身体姿势（人类为直立，四足动物、鱼类和七鳃鳗为背侧朝上）。我们将讨论在一种低等脊椎动物（七鳃鳗）以及两种哺乳动物（兔子和猫）中研究的脊髓和脊髓上姿势网络的运作。在七鳃鳗中，姿势控制系统由前庭输入驱动。姿势网络中的关键作用属于网状脊髓（RS）神经元。由于前庭输入，在任何（滚动、俯仰、偏航）平面上偏离稳定的身体姿势都会导致RS指令的产生，这些指令被发送到脊髓并引起姿势校正。对于每个平面，有两组RS神经元对相反方向的旋转做出反应；它们会导致与初始旋转方向相反的转动。单个RS神经元传递的指令会引起运动反应，这有助于姿势的校正。在每个平面中，姿势系统将姿势稳定在拮抗前庭反射相互补偿的方向上。因此，在七鳃鳗中，脊髓上网络在身体姿势稳定中起关键作用，而脊髓网络的功能是将脊髓上指令转化为姿势校正的运动模式。在陆生四足动物中，分析了稳定躯干在横向平面姿势的姿势系统。它由两个相对独立的子系统组成，分别稳定躯干前部和后部的姿势。它们由来自肢体机械感受器的体感输入驱动。每个子系统由两个闭环机制组成——脊髓和脊髓 - 脊髓上机制。通过记录皮质脊髓神经元与姿势相关的活动来研究脊髓上网络的运作。在脊髓损伤的动物中评估脊髓网络的姿势能力。讨论了脊髓和脊髓上机制对躯干姿势稳定的相对贡献。
