Trajectory control in targeted force impulses. VII. Independent setting of amplitude and direction in response preparation.
Trajectory control in targeted force impulses. VII. Independent setting of amplitude and direction in response preparation.
复制标题
目标力脉冲的轨迹控制。
DOI：
10.1007/bf00229322
复制
发表时间：
1990
影响因子：
2
通讯作者：
Ghez,C
中科院分区：
文献类型：
--
作者：
Favilla,M;Gordon,J;Hening,W;Ghez,C
我们以前已经表明，当针对不可预测的屈曲和伸展目标的力脉冲时，受试者通过预先选择默认的幅度和方向来准备响应。在我们之前的研究中，屈曲和伸展目标范围是对称的，受试者在两个范围的中心附近准备一个默认振幅，并任意选择一个默认方向（Favilla，Hening等，1989）。在目标呈现之后，逐渐且平行地指定幅度和方向。通过使用一个实验范例，其中目标振幅在两个方向中的一个方向上具有不相等的概率，我们不试图确定受试者准备的默认振幅在多大程度上取决于为给定试验选择的默认方向。五名正常人产生等长肘关节屈曲和伸展力脉冲，以匹配四个目标，需要在每个方向上的两个振幅的响应。靶板和延伸靶板大小相同。在所有有偏概率条件下，目标以不可预测的顺序呈现，并且在一个方向上，目标的发生概率是有偏的（80%对20%）。在另一个方向上，两个目标的概率相等。为了最大限度地提高响应参数的默认设置的效果，我们要求受试者启动他们的响应同步与可预测的音调发生不到一个反应时间后的视觉目标的介绍。选择如此短的间隔是为了通过限制刚刚呈现的目标对受试者响应的幅度和方向的影响来揭示所选择的默认参数。如果默认振幅是独立于所选的反应方向准备的，则受试者应在两个方向上显示默认振幅的偏倚。相反，如果默认振幅与方向相关联，则偏差将仅发生在目标振幅具有不等概率的方向上。对于控制，我们提出了相同的四个目标，在可预测的系列（简单条件）和不可预测的系列没有任何偏见（选择条件）。当呈现的目标，其幅度是不平等的概率，只有一个方向，所有的科目表现出强烈的偏见，他们的反应幅度在两个方向。该结果适用于所有受试者，并且独立于响应方向（屈曲或伸展）或响应是否与当前目标方向相同或相反（即错误方向）。当反应方向与目标方向相同且概率不相等时，这种偏差最大。我们的结论是，受试者准备默认的幅度，在很大程度上，独立的方向作出的反应不可预测的目标。本研究结果扩展了我们的证明，受试者可以执行不同的组件过程的感觉运动处理，如规格的响应幅度和方向，通过并行处理通道。
We have previously shown that when aiming impulses of force to unpredictable flexion and extension targets, subjects prepare themselves to respond by preselecting a default amplitude and direction. In our preceding study, where flexion and extension target ranges were symmetrical, subjects prepared a single default amplitude near the center of each of the two ranges and selected a default direction arbitrarily (Favilla, Hening et al. 1989). Following target presentation, amplitude and direction were specified gradually and in parallel. By using an experimental paradigm in which target amplitudes had unequal probabilities in only one of the two directions, we no sought to determine to what extent the default amplitude prepared by subjects is dependent on the default direction that is selected for a given trial. Five normal subjects produced isometric elbow flexion and extension force impulses to match four targets requiring responses of two amplitudes in each direction. Flexion and extension targets were of the same size. In all biased probability conditions, targets were presented in unpredictable order and, in one direction, the probability of occurrence of the targets was biased (80% versus 20%). In the other direction, the two targets were equiprobable. To maximize the effect of the default settings on response parameters, we required subjects to initiate their response in synchrony with a predictable tone occuring less than a reaction time subsequent to the presentation of the visual target. Such a short interval was chosen to disclose the default parameters selected by limiting the influence of the target just presented on the amplitude and direction of the subjects' responses. If the default amplitude were prepared independently of the response direction selected, subjects should show a bias in the default amplitude in both directions. In contrast, if default amplitudes were associated with direction, the bias would occur only in the direction whose target amplitudes had unequal probability. For controls, we presented the same four targets both in predictable series (simple condition) and in unpredictable series without any bias (choice condition). When presented with targets whose amplitudes were of unequal probability in only a single direction, all subjects showed a strong bias in the amplitudes of their responses in both directions. This result was true of all subjects and occurred independently of the response direction (flexion or extension) or whether the response was in the same direction as the current target or the opposite direction (i.e. wrong direction). This bias was strongest when responses were made in the same direction as the targets with unequal probability. We conclude that subjects prepare default amplitudes that are, in large measure, independent of the direction of responses made to unpredictable targets. The present results expand our demonstration that subjects may perform different component processes of sensorimotor processing, such as specification of response amplitude and direction, by parallel processing channels.