Castiello U, Bennett K, Chambers H
Department of Psychology, The University of Melbourne, Parkville, Victoria, Australia.
Exp Brain Res. 1998 May;120(1):31-40. doi: 10.1007/s002210050375.
This study assessed the reach to grasp movement and its adaptive response to a simultaneous perturbation of object location and size. The aim was to clarify the means by which integration between the neural pathways modulating transport and manipulation is achieved. Participants (n = 11) were required to reach 30 cm to grasp a central illuminated cylinder of either small (0.7 cm) or large (8 cm) diameter. For a small percentage of trials (20/100) a visual perturbation was introduced unexpectedly at the onset of the reaching action. This consisted of a shift of illumination from the central cylinder to a cylinder of differing diameter (large in session A; small in session B) that was positioned 20 degrees to the left (n = 10 trials) or to the right (n = 10) of the central cylinder. The subject was required to grasp the newly illuminated cylinder. Movement duration for these "double" (position and size) perturbed trials was much longer than those of control trials to the central cylinder (session A: by an average of 250 ms; session B: 180 ms), and the increased values were much greater than those reported previously in "single" perturbation studies where either size or location of the object was perturbed. Initial signs of a response to the "double" perturbation were seen almost simultaneously in the transport parameter of peak arm deceleration and in the manipulation parameter of maximum grip aperture, but these changes were not evident until more than 400 ms after movement onset, a response onset much later than that found in "single" perturbation studies. It is proposed that the visual change resultant from the double perturbation activates integration centres that at first gate the flow of information to the parallel channels of transport and manipulation. Following processing of this information, these centres act to instigate a synchronised and coordinated response in both components. These results add support to the existence of neural centres dedicated to the integration of parallel neural pathways, and which exercise flexibility in the degree to which these components are "coupled" functionally.
本研究评估了伸手抓握动作及其对物体位置和大小同时受到扰动时的适应性反应。目的是阐明调节运输和操作的神经通路之间实现整合的方式。参与者（n = 11）被要求伸手30厘米去抓握一个位于中央的发光圆柱体，其直径要么小（0.7厘米）要么大（8厘米）。在一小部分试验（20/100）中，在伸手动作开始时意外引入了视觉扰动。这包括照明从中央圆柱体转移到一个直径不同的圆柱体（A组为大直径；B组为小直径），该圆柱体位于中央圆柱体左侧20度（n = 10次试验）或右侧（n = 10次）。受试者被要求抓握新照亮的圆柱体。这些“双重”（位置和大小）受扰动试验的运动持续时间比抓握中央圆柱体的对照试验长得多（A组：平均长250毫秒；B组：180毫秒），且增加的值比之前在“单一”扰动研究中报告的值大得多，在“单一”扰动研究中物体的大小或位置受到扰动。对“双重”扰动的反应的初始迹象几乎同时出现在手臂峰值减速的运输参数和最大抓握孔径的操作参数中，但这些变化直到运动开始后400多毫秒才明显，反应开始时间比“单一”扰动研究中发现的要晚得多。有人提出，双重扰动产生的视觉变化激活了整合中心，这些中心首先控制流向运输和操作平行通道的信息流。在处理这些信息之后，这些中心促使两个组件做出同步和协调的反应。这些结果支持了存在专门用于整合平行神经通路的神经中心，并且这些中心在功能上对这些组件“耦合”的程度具有灵活性。
