Tactile discrimination of shape: responses of rapidly adapting mechanoreceptive afferents to a step stroked across the monkey fingerpad
Tactile discrimination of shape: responses of rapidly adapting mechanoreceptive afferents to a step stroked across the monkey fingerpad
复制标题
形状的触觉辨别：快速适应机械感受传入对猴子指垫上的步骤的反应
DOI：
10.1523/jneurosci.07-06-01672.1987
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发表时间：
1987
影响因子：
2.5
通讯作者：
M. Srinivasan
中科院分区：
文献类型：
--
作者：
R. LaMotte;M. Srinivasan
在麻醉猕猴上记录了触觉小体机械感受性传入纤维(RAS)对指垫远端不同形状台阶的快速适应反应。使用了一系列平板，每个平板在中间增加了厚度(一个台阶)，使得平板的一半比另一半厚。台阶的横截面形状类似于半周期正弦形，高0.5 mm。正弦阶梯的宽度(半周期波长)从0到3.13 mm变化，产生了一系列陡度和曲率不同的阶梯形状。这些步骤可以大致分为两类，“陡峭的”和“渐进的”。使用伺服控制的机械刺激器，在恒定的压缩力下来回敲击每一步。RA对一个台阶的反应提供了一个动作电位的空间模式，其中每个脉冲的出现都与该台阶在皮肤上的位置相对应。这一反应包括对台阶正弦部分的一次脉冲“爆发”。卒中方向、台阶形状或卒中速度的改变主要影响爆发期间的RA放电率，而不太一致地影响爆发的空间宽度。对于给定的步型和笔划速度，从低到高的笔划的放电速率大于从高到低的笔划。陡峭台阶的放电速率大于渐进台阶的放电速率，并且对于给定的台阶，放电速率随着击打速度的增加而增加。所有反应的主要特征被解释为主要是由于RA对其感受场上最敏感的部位的垂直速度的敏感性，以及对该部位皮肤曲率变化率的敏感性。RA放电率不仅区分陡峭和渐变台阶之间的总体差异，而且区分陡峭台阶之间在锐度上的一些细微差异。通过与人类对台阶的触觉辨别能力的比较，得出结论，RAS通过它们的放电率，主要提供关于形状锐度的“密集”信息。
Responses of rapidly adapting Meissner corpuscle mechanoreceptive afferent fibers (RAs) to steps of varying shape stroked across the distal fingerpad were recorded from anesthetized monkeys. A series of flat plates were used, each having an increase in thickness (a step) in the middle so that one-half of the plate was thicker than the other. The cross-sectional shape of the step approximated that of a half-cycle sinusoid, 0.5 mm high. The width (half-cycle wavelength) of the sinusoidal step was varied from 0 to 3.13 mm, producing a series of step shapes that differed in steepness and curvature. These steps could be broadly categorized into 2 groups, “steep” and “gradual.” Each step was stroked back and forth under constant compressional force, using a servocontrolled mechanical stimulator. The RA's response to a step provided a spatial pattern of action potentials in which the occurrence of each impulse corresponded to a position of the step on the skin. This response consisted of a single “burst” of impulses to the sinusoidal portion of the step. Changes in stroke direction, step shape, or velocity of stroking primarily affected the RA discharge rate during the burst, and, less consistently, the spatial width of the burst. For a given step shape and stroke velocity, the discharge rate was greater for strokes from the low to the high side of the step than for strokes from the high to the low side. Discharge rate was greater for steep than for gradual steps and, for a given step, it increased with stroke velocity. All the major features of the responses were interpreted as being due predominantly to the sensitivity of the RA to vertical velocity at the most sensitive spot on its receptive field, together with a sensitivity to the rate of change in skin curvature at that spot. RA discharge rate distinguished not only the gross differences between steep and gradual steps, but also some of the finer differences in sharpness among steep steps. From a comparison with the human capacity for tactile discrimination of the steps, it was concluded that RAs, through their discharge rates, provide primarily “intensive” information about the sharpness of shapes.