Understanding sensorimotor feedback through optimal control.
Understanding sensorimotor feedback through optimal control.
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通过最优控制了解感觉运动反馈。
DOI：
10.1101/sqb.1990.055.01.074
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
He,J
中科院分区：
文献类型：
--
作者：
Loeb,GE;Levine,WS;He,J
一般的“控制”问题可分为两大类，通常指定为开环和闭环(见图1)。我们在这里采用的惯例是使用“控制器”来指定一种设备，该设备制定一组旨在改变系统状态的命令，这些命令是开环执行的，即在任务期间不进行修改。(我们强调这是一个速记术语，不要与控制理论中表示开环和闭环组件的标准用法混淆。)我们使用术语“调节器”来指代试图稳定系统状态的设备，该设备仅产生闭环系统命令，即对系统中传感器检测到的状态偏差的响应(Bryson和Ho 1975)。显然，大多数复杂系统需要这两种类型的控制的混合。在感觉运动神经生理学中，通常将这类对照描述为独立的，尽管它们所在结构的解剖学和生理学特征表明它们之间存在密切的联系。例如，四足动物的运动控制被认为分为脊髓中央模式发生器(CPG)和各种反射，前者产生肌肉激活的开环程序，后者也主要是脊髓反射，后者对内部错误和外部干扰做出反应来调整激活。Liddell和Sherrington(1925)首先提出运动神经元的概念，将各种控制信号源相加，形成对运动单元的网络命令。现在毫无疑问的是，像大多数中枢神经元一样，运动神经元将许多不同的输入来源整合成一个单一维度的输出。然而，后一种认为这些运动神经元的输入可以区分为开环和闭环类型的观点值得重新审视。从长远来看，Sherrington(1910)自己认为运动主要是通过反射路径产生的，即来自肢体肌肉骨骼机械产生的感觉信号的顺序组合。后来，在瘫痪、去瘫痪的人的虚构运动中报告的运动神经元输出的令人惊讶的自然时间模式，确定了对运动控制器的需求。
The general problem of" control" may be divided into two main categories, often designated open-loop and closed-loop (see Fig. 1). We adopt here the convention of using" controller" to designate a device that formulates a set of commands intended to change the state of a system, which commands are executed openloop, ie, without modification during the task.(We emphasize that this is a shorthand terminology, not to be confused with the standard usage in control theory denoting both open-and closed-loop components.) We use the term" regulator" to designate a device that attempts to stabilize the state of a system, generating only closed-loop commands, ie, responses to deviations from the state detected by sensors in the system (Bryson and Ho 1975). Obviously, most complex systems require a mixture of the two types of control. In sensorimotor neurophysiology, it is common to depict these kinds of controls schematically as if they were separate, even though the anatomical and physiological features of the structures in which they reside suggest a close interrelatedness. For example, the control of locomotion in quadrupeds has been seen as divided between a spinal central pattern generator (CPG), which generates an open-loop program of muscle activation, and various reflexes, also largely spinal, which adjust the activation in response to internal errors and external perturbations. Liddell and Sherrington (1925) first proposed the concept of the motoneuron as the" final common path" whereby the various sources of control signals would be summed to result in the net command to a motor unit. There is now little doubt that the motoneuron, like most central neurons, serves to integrate many disparate sources of input into a single-dimensional output. However, the later notion that these motoneuronal inputs are distinguishable into open-loop and closed-loop types deserves reexamination.Ironically, Sherrington (1910) himself felt that locomotion was produced primarily through reflex pathways, ie, from the sequential combination of sensory signals arising from the musculoskeletal mechanics of the limb. The need for an open-loop controller of locomotion was firmly established later by the surprisingly natural temporal patterns of motoneuronal output reported during fictive locomotion in paralyzed, de-