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首页> 外文期刊>Journal of Neurophysiology >Neuronal activity in somatosensory cortex of monkeys using a precision grip. III. Responses to altered friction perturbations.
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Neuronal activity in somatosensory cortex of monkeys using a precision grip. III. Responses to altered friction perturbations.

机译：使用精密握把在猴子的体感皮质中进行神经元活动。三，对变化的摩擦扰动的反应。

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摘要

The purpose of this investigation was to examine the activity changes in single units of the somatosensory cortex in response to lubricating and adhesive coatings applied to a hand-held object. Three monkeys were trained to grasp an object between the thumb and index fingers and to lift and hold it stationary within a narrow position window for 1 s before release. Grip forces normal to the skin surface, load forces tangential to the skin surface, and the displacement of the object were measured on each trial. Adhesive (rosin) and lubricant (petroleum jelly) coatings were applied to the smooth metal surface of the object to alter the friction against the skin. In addition, neuronal activity evoked by force pulse-perturbations generating shear forces and slip on the skin were compared with the patterns of activity elicited by grasping and lifting the coated surfaces. Following changes in surface coatings, both monkeys modulated the rate at which grip forces normal to the skin surface and load forces tangential to the skin surface were applied during the lifting phase of the task. As a result, the ratio of the rates of change of the two forces was proportionately scaled to the surface coating properties with the more slippery surfaces, having higher ratios. This precise control of normal and tangential forces enabled the monkeys to generate adequate grip forces and prevent slip of the object. From a total of 386 single neurons recorded in the hand area of the somatosensory cortex, 92 were tested with at least 1 coating. Cell discharge changed significantly with changes in surface coating in 62 (67%) of these cells. Of these coating-related cells, 51 were tested with both an adhesive and lubricating coating, and 45 showed significant differences in activity between the untreated metal surface and either the lubricant or the adhesive coating. These cells were divided into three main groups on the basis of their response patterns. In the first group (group A), the peak discharge increased significantly when the grasped surface was covered with lubricant. These cells appeared to be selectively sensitive to slip of the object on the skin. The second group (group B) was less activated by the adhesive surface compared with either the untreated metal or the lubricated surface, and they responded mainly to variations in the force normal to the skin surface. These cells provide useful feedback for the control of grip force. The third group (group C) responded to both slips and to changes in forces tangential to the skin. Most of these cells responded with a biphasic pattern reflecting the bidirectional changes in load force as the object was first accelerated and then decelerated. One hundred sixty-eight of the 386 isolated neurons were tested with brief perturbations during the task. Of these, 147 (88%) responded to the perturbation with a significant change in activity. In most of the cells, the response to the perturbation was shorter than 100 ms with a mean latency of 44.1 +/- 16.3 (SD) ms. For each of the cell groups, the activity patterns triggered by the perturbations were consistent with the activity patterns generated during the grasping and lifting of the coated object.
机译：这项研究的目的是检查响应于应用于手持对象的润滑和粘合涂层后，体感皮层单个单元的活性变化。对三只猴子进行了训练，以抓住拇指和食指之间的物体，并在狭窄的位置窗口内将其提起并保持静止1秒钟，然后释放。在每次试验中均测量垂直于皮肤表面的握力，与皮肤表面相切的负载力以及物体的位移。将粘性（松香）和润滑剂（凡士林）涂层涂在物体的光滑金属表面上，以改变对皮肤的摩擦。另外，将由在皮肤上产生剪切力和滑动的力脉冲扰动引起的神经元活动与通过抓握和提起涂层表面引起的活动模式进行了比较。随着表面涂层的变化，两只猴子调节了在任务的提升阶段施加垂直于皮肤表面的抓力和切向皮肤表面的载荷的速率。结果，两个力的变化率的比率与具有更高比率的更光滑表面的表面涂层性能成比例地缩放。对法向和切向力的精确控制使猴子能够产生足够的抓地力并防止物体滑落。从体感皮层的手部区域记录的总共386个单神经元中，用至少1种涂层测试了92个。这些电池中有62个（67％）的电池放电随表面涂层的变化而显着变化。在这些与涂层有关的电池中，有51个用粘合和润滑涂层进行了测试，有45个在未处理的金属表面与润滑剂或粘合涂层之间显示出明显的活性差异。根据它们的反应模式将这些细胞分为三个主要组。在第一组（A组）中，当抓握的表面被润滑剂覆盖时，峰值放电显着增加。这些细胞似乎对物体在皮肤上的滑动有选择地敏感。与未经处理的金属或经润滑的表面相比，第二组（B组）被粘着剂表面活化的较少，并且它们主要响应于垂直于皮肤表面的力的变化。这些单元为控制抓地力提供有用的反馈。第三组（C组）对滑动和与皮肤相切的力的变化都做出了响应。这些物体中的大多数以双相模式响应，反映了物体首先加速然后减速时负载力的双向变化。在执行任务期间，对386个孤立的神经元中的168个进行了短暂的扰动测试。其中，有147名（88％）的摄动对活动产生了明显的变化。在大多数细胞中，对摄动的反应短于100毫秒，平均潜伏期为44.1 +/- 16.3（SD）毫秒。对于每个细胞组，由扰动触发的活动模式与在抓握和提起被涂层物体时产生的活动模式一致。

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