The effect upon the threshold for nervous excitation of the length of nerve exposed, and the angle between current and nerve
The effect upon the threshold for nervous excitation of the length of nerve exposed, and the angle between current and nerve
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神经暴露长度、电流与神经夹角对神经兴奋阈值的影响
DOI：
10.1113/jphysiol.1927.sp002409
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发表时间：
1927
期刊：
影响因子：
--
通讯作者：
W. Rushton
中科院分区：
文献类型：
--
作者：
W. Rushton
导论.众所周知，当电极之间的距离增加时，刺激神经所需的最小电流减小。过去曾提出过各种各样的解释，但由于大多数工作是在大约50年前完成的，从目前的观点来看，这些解释有些不令人满意。当时流行的关于神经活动的一般观念，后来被两个特别的概念所修正，并变得更加精确。首先，卢卡斯和其他人的工作区分了两种形式的活动，“局部兴奋过程”和“传播干扰”。兴奋的阈值被证明纯粹取决于局部现象，神经的较远部分对刺激的成功或失败没有其他影响，而不是“有时阻止已经开始的传播干扰”。第二，离子假说阐明了电在介质（如构成组织的介质）中通过的性质，并表明所引起的任何变化都必须通过离子的作用而发生。能斯特（1）将这一概念应用于神经兴奋性问题，并假设离子运动本身不会产生影响，他立即提出了膜假说。根据这一点，刺激电流仅通过所引起的离子浓度的变化而起作用，并且这种变化仅能发生在与离子流动相反的东西（例如，半透膜）的附近。能斯特进一步假设，不仅局部兴奋过程取决于离子浓度，而且离子浓度总是激发的限制因素。因此他
Introduction. It is well known that the minimum current required to excite a nerve decreases when the distance between the electrodes is increased. Various explanations have been proposed in the past, but since most of the work was done some fifty years ago, they are somewhat unsatisfactory from the present standpoint. The general ideas of nervous activity then in vogue have since been modified and made more precise by two conceptions in particular. First the work of Lucas and others distinguished between the two forms of activity, "the local excitatory process," and "the propagated disturbance." The threshold for excitation was shown to depend upon purely local phenomena, and the remoter parts of the nerve had no other effect on the success or failure of a stimulus than' sometimes to block the propagated disturbance which had already been initiated. Second, the ionic hypothesis elucidated the nature of the passage of electricity in media such as those of which the tissues are composed, and showed that any change which was brought about must occur through the action of ions. Nernst(1) applied this concept to the problem of nervous excitability, and, assuming that movement of ions per se could have no effect, he was immediately brought to his membrane hypothesis. According to this a stimulating current acts only through the changes in ionic concentration which are brought about, and such changes can only occur in the neighbourhood of something which opposes the flow of ions, e.g. a semi-permeable membrane. Nernst made the further assumption that not only did the local excitatory process depend upon the ionic concentration, but that this concentration was always the limiting factor in excitation. He therefore