Flindall Jason W, Gonzalez Claudia L R
The Brain in Action Lab, Department of Kinesiology, University of Lethbridge, 4401 University Ave, 44 Mt Rundle Blvd W, Lethbridge, AB, T1K 3M4, Canada.
Exp Brain Res. 2017 Jun;235(6):1945-1952. doi: 10.1007/s00221-017-4943-2. Epub 2017 Mar 21.
Previous studies in our lab have described kinematic difference between grasp-to-eat and grasp-to-place movements, whereby participants produce smaller maximum grip apertures (MGAs) when grasping to bring the item to the mouth than when grasping to bring the item to a container near the mouth. This task difference is limited to right-handed movements, regardless of handedness; it has, therefore, been interpreted as evidence of left-hemisphere lateralization of the grasp-to-eat and other hand-to-mouth grasping movements. However, the difference in end-goal aperture may have accounted for both the kinematic signature (smaller MGAs) and their lateralized expression. Specifically, if the right hand is more sensitive to the precision requirements of secondary movements, it may have produced more precise MGAs for actions whose ultimate goal is the small-aperture mouth rather than a comparatively large aperture container. The current study addresses this question by replacing the previously-used bib with a small drinking glass whose aperture more closely resembles that of the mouth. 25 adult participants reached-to-grasp small cereal items to either (a) eat them, or (b) place them into a small-aperture glass hanging beneath their chin. Results once more showed a lateralised kinematic signature in the form of smaller MGAs for the eat action, demonstrating that the signature is not a result of lateralized sensitivity to a movement's secondary precision requirements. We discuss these results in terms of their impact on predominant theories regarding visual guidance of grasping movements.
我们实验室之前的研究描述了抓握取食和抓握放置动作之间的运动学差异，即参与者在抓握物品并将其送至嘴边时产生的最大抓握孔径（MGA），比抓握物品并将其送至嘴边附近的容器时要小。这种任务差异仅限于右手动作，与利手无关；因此，它被解释为抓握取食和其他手到嘴的抓握动作左半球侧化的证据。然而，最终目标孔径的差异可能既解释了运动学特征（较小的MGA）及其侧化表现。具体而言，如果右手对后续动作的精度要求更敏感，那么对于最终目标是小嘴而非相对大孔径容器的动作，它可能会产生更精确的MGA。当前的研究通过用一个孔径更接近嘴部的小水杯替换之前使用的围嘴来解决这个问题。25名成年参与者伸手去抓小谷物食品，要么（a）吃掉它们，要么（b）将它们放入挂在下巴下方的小口径玻璃杯中。结果再次显示，进食动作以较小的MGA形式呈现出侧化运动学特征，表明该特征不是对动作后续精度要求的侧化敏感性的结果。我们将根据这些结果对抓握动作视觉引导的主流理论的影响来进行讨论。
