MEMORY REPRESENTATIONS UNDERLYING MOTOR COMMANDS USED DURING MANIPULATION OF COMMON AND NOVEL OBJECTS
MEMORY REPRESENTATIONS UNDERLYING MOTOR COMMANDS USED DURING MANIPULATION OF COMMON AND NOVEL OBJECTS
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DOI：
10.1152/jn.1993.69.6.1789
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发表时间：
1993-06-01
影响因子：
2.5
通讯作者：
JOHANSSON, RS
中科院分区：
文献类型：
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作者：
GORDON, AM;WESTLING, G;JOHANSSON, RS
1. 当被试举起各种不同形状、重量和密度的常用物体时，从模拟重量秤上记录相对于物体重量的等距垂直举升力，该重量秤配有高刚度应变传感器。在获得与物体重量相关的感官信息之前，从第一次提升开始，不同物体的力输出是不同的。根据内存中与普通物体重量相关的信息，成功地指定了力输出，因为在连续10次提升中，力率曲线只发生了很小的变化。该信息是在与目标对象的视觉识别相关的过程中检索的。当遇到不同密度的新物体（在抓握面装有力传感器）时，适当调整垂直提升和抓握（捏）力所需的练习量也进行了研究。在不改变物体外观的情况下，通过在物体底部插入适当的质量，将受试者之前未见过的测试物体的质量调整为300或1,000 g。这导致密度要么在最常见物体的范围内（1.2 kg/ 1），要么密度异常高（4.0 kg/ 1）。低垂直提升和握力率最初用于高密度物体，就好像一个更轻的物体已经被预期。然而，在最初的几次试验中，加载阶段的持续时间（起飞前等距力增加的时间）减少了近50%，所使用的力率曲线是针对物体的重量的。当24小时后举起同一物体时，力的比例仍然适应物体的重量。相比之下，提升具有更常见密度的新物体，从第一次提升开始，在连续的试验中，加载阶段持续时间和峰值力率都很稳定。因此，对于不熟悉的物体，受试者会假设一个默认密度来推断物体的重量，该密度在通常遇到的密度范围内，并与尺寸线索结合使用。结论是，人类使用预期控制将运动指令与熟悉物体的重量相匹配。记忆信息具有鲁棒性，可以通过对目标物体的视觉识别进行检索，并且与新物体的权重相关的准确记忆表征发展迅速。这种预期控制具有高度的目的性，因为它允许在日常任务中进行快速而准确的操作，而不受严格依赖“即时”感官反馈控制所施加的限制。
1. While subjects lifted a variety of commonly handled objects of different shapes, weights, and densities, the isometric vertical lifting force opposing the object's weight was recorded from an analog weight scale, which was instrumented with high-stiffness strain gauge transducers.2. The force output was scaled differently for the various objects from the first lift, before sensory information related to the object's weight was available. The force output was successfully specified from information in memory related to the weight of common objects, because only small changes in the force-rate profiles occurred across 10 consecutive lifts. This information was retrieved during a process related to visual identification of the target object.3. The amount of practice necessary to appropriately scale the vertical lifting and grip (pinch) force was also studied when novel objects (equipped with force transducers at the grip surfaces) of different densities were encountered. The mass of a test object that subjects had not seen previously was adjusted to either 300 or 1,000 g by inserting an appropriate mass in the object's base without altering its appearance. This resulted in either a density that was in the range of most common objects ( 1.2 kg/ 1) or a density that was unusually high (4.0 kg/ 1).4. Low vertical-lifting and grip-force rates were used initially with the high-density object, as if a lighter object had been expected. However, within the first few trials, the duration of the loading phase (period of isometric force increase before lift-off) was reduced by nearly 50% and the employed force-rate profiles were targeted for the weight of the object. The force scaling was still adapted to the object's weight when lifting the same object 24 h later.5. In contrast, lifting a novel object with a more common density yielded stable loading phase durations and peak-force rates across consecutive trials, beginning with the first lift. Thus, for unfamiliar objects, subjects infer the object's weight assuming a default density that is within a range of commonly encountered densities and used in combination with size cues.6. It is concluded that humans use anticipatory control to scale motor commands to the weight of familiar objects. The memory information is robust and can be retrieved through visual identification of the target object, and accurate memory representations related to the weight of novel objects develop quickly. Such anticipatory control is highly purposeful because it allows quick and accurate manipulation during everyday tasks that is not subject to limitations imposed by a strict dependence on ''moment-to-moment'' sensory feedback control.