Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium.
Institute of Information and Communication Technologies, Electronics and Applied Mathematics, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
J Neurophysiol. 2021 Oct 1;126(4):1455-1464. doi: 10.1152/jn.00358.2021. Epub 2021 Sep 8.
During active object manipulation, the finger-object interactions give rise to complex fingertip skin deformations. These deformations are in turn encoded by the local tactile afferents and provide rich and behaviorally relevant information to the central nervous system. Most of the work studying the mechanical response of the finger to dynamic loading has been performed under a passive setup, thereby precisely controlling the kinematics or the dynamics of the loading. However, to identify aspects of the deformations that are relevant to online control during object manipulation, it is desirable to measure the skin response in an active setup. To that end, we developed a device that allows us to monitor finger forces, skin deformations, and kinematics during fine manipulation. We describe the device in detail and test it to precisely describe how the fingertip skin in contact with the object deforms during a simple vertical oscillation task. We show that the level of grip force directly influences the fingerpad skin strains and that the strain rates are substantial during active manipulation (norm up to 100%/s). The developed setup will enable us to causally relate sensory information, i.e. skin deformation, to online control, i.e. grip force adjustment, in future studies. We present a novel device, a manipulandum, that enables to image the contact between the finger and the contact surface during active manipulation of the device. The device is tested in a simple vertical oscillation task involving 18 participants. We demonstrate that substantial surface skin strains take place at the finger-object interface and argue that those deformations provide essential information for grasp stability during object manipulation.
在主动物体操作过程中，手指与物体的相互作用会导致指尖皮肤产生复杂的变形。这些变形被局部触觉传入纤维编码，并为中枢神经系统提供丰富且与行为相关的信息。大多数研究手指对动态加载的机械响应的工作都是在被动设置下进行的，从而精确地控制加载的运动学或动力学。然而，为了识别在物体操作过程中与在线控制相关的变形方面，有必要在主动设置下测量皮肤的响应。为此，我们开发了一种设备，可以在精细操作过程中监测手指力、皮肤变形和运动学。我们详细描述了该设备并对其进行了测试，以精确描述在简单垂直振荡任务中与物体接触的指尖皮肤是如何变形的。我们表明，握力水平直接影响指垫皮肤应变，并且在主动操作期间应变率很大（正常情况下高达 100%/s）。所开发的设置将使我们能够在未来的研究中使感觉信息（即皮肤变形）与在线控制（即握力调整）相关联。我们提出了一种新颖的设备，即操纵器，它可以在主动操纵设备的过程中对手指与接触表面之间的接触进行成像。该设备在涉及 18 名参与者的简单垂直振荡任务中进行了测试。我们证明在手指与物体的界面处会发生相当大的表面皮肤应变，并认为这些变形为物体操作过程中的抓握稳定性提供了重要信息。
