Motor task difficulty and brain activity: Investigation of goal-directed reciprocal aiming using positron emission tomography
Motor task difficulty and brain activity: Investigation of goal-directed reciprocal aiming using positron emission tomography
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DOI：
10.1152/jn.1997.77.3.1581
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发表时间：
1997-03-01
影响因子：
2.5
通讯作者：
Pohl, PS
中科院分区：
文献类型：
--
作者：
Winstein, CJ;Grafton, ST;Pohl, PS
采用Fitts连续瞄准模式，采用基于视频的运动轨迹分析和正电子发射断层扫描技术，对6名健康右利手年轻受试者在目标导向手臂瞄准过程中的运动学和相对局部脑血流（rCBF）模式的差异进行了研究。运动时间和运动学特征与脑血流量的大小一起进行分析，以确定与任务和运动变量成比例的大脑活动区域。通过方差分析确定任务条件之间rCBF的显著差异，并使用组平均值加权线性对比进行计划的平均值比较。首先对该组的数据进行分析。然后通过磁共振成像将运动与不运动的个体受试者差异和任务难度比较与每个个体受试者的解剖结构相关。与无运动条件相比，在相互瞄准过程中，在与目标导向运动的规划和执行相关的众所周知的皮质和皮质下区域的马赛克中发现了rCBF的显着差异。这些包括左侧感觉运动区、背侧运动前区和腹侧运动前区皮质、尾侧辅助运动区（SMA）、顶叶皮质以及左侧壳核、苍白球、红核、丘脑和小脑前部的皮质下区域。随着瞄准任务难度（ID）的增加，与需要更大视觉处理的更复杂动作的规划相关的区域的rCBF增加。包括双侧枕叶、左侧顶下叶和左侧背侧扣带皮层-尾侧SMA固有区和右侧背侧运动前区。这些相同的领域表现出显着的增加或减少，分别当对比度平均值与使用的运动时间或相对加速时间，分别作为加权因子进行比较。个体受试者差异的分析显示，作为任务ID和个人的运动时间的函数的rCBF变化的空间范围之间的对应关系。随着任务ID的减少，右侧小脑前区、左侧枕中回和右侧腹侧运动前区的rCBF明显增加。在功能上，这些区域与其中电机执行需求高的瞄准条件相关联（即，快速反向的协调）和精确的轨迹规划是最小的。这些相同的领域表现出显着的增加或减少，分别当对比度平均值与使用的运动时间或相对加速时间，分别作为加权因子进行比较。功能分离是由较大（肢体运输）或较小（终点靶向）类型振幅/目标宽度瞄准条件之间的加权线性对比引起的。具有显著更大rCBF的靶向区域是左侧运动皮质、左侧顶内沟和左侧尾状核。相反，与肢体运输相关的rCBF较大的区域包括双侧枕舌回和右侧小脑前叶。各种理论解释的速度/准确性权衡的快速瞄准运动已经提出了，因为原来的信息理论假说的Fitts.This是第一份报告，涉及到可预测的变化，在不断变化的任务约束下，这些快速目标导向的瞄准运动的功能解剖的运动控制。单手瞄准任务难度的差异导致皮层-皮层下网络的可分离激活，这些数据进一步表明，当需要更精确的瞄准时，独立于任务难度，由对侧运动皮层、顶内沟和尾状核组成的皮层-皮层下回路被激活。这与运动皮层在群体编码的基础上控制运动方向的作用是一致的。
Differences in the kinematics and pattern of relative regional cerebral blood flow (rCBF) during goal-directed arm aiming were investigated with the use of a Fitts continuous aiming paradigm with three difficulty conditions (index of difficulty, ID) and two aiming types (transport vs. targeting) in six healthy right-handed young participants with the use of video-based movement trajectory analysis and positron emission tomography. Movement time and kinematic characteristics were analyzed together with the magnitude of cerebral blood flow to identify areas of brain activity proportionate to task and movement variables. Significant differences in rCBF between task conditions were determined by analysis of variance with planned comparisons of means with the use of group mean weighted linear contrasts. Data were first analyzed for the group. Then individual subject differences for the movement versus no movement and task difficulty comparisons were related to each individual subjects' anatomy by magnetic resonance imaging. Significant differences in rCBF during reciprocal aiming compared with no-movement conditions were found in a mosaic of well-known cortical and subcortical areas associated with the planning and execution of goal-directed movements. These included cortical areas in the left sensorimotor, dorsal premotor, and ventral premotor cortices, caudal supplementary motor area (SMA) proper, and parietal cortex, and subcortical areas in the left putamen, globus pallidus, red nucleus, thalamus, and anterior cerebellum. As aiming task difficulty (ID) increased, rCBF increased in areas associated with the planning of more complex movements requiring greater visuomotor processing. These included bilateral occipital, left inferior parietal, and left dorsal cingulate cortices-caudal SMA proper and right dorsal premotor area. These same areas showed significant increases or decreases, respectively, when contrast means were compared with the use of movement time or relative acceleration time, respectively, as the weighting factor. Analysis of individual subject differences revealed a correspondence between the spatial extent of rCBF changes as a function of task ID and the individuals' movement times. As task ID decreased, significant increases in rCBF were evident in the right anterior cerebellum, left middle occipital gyrus, and right ventral premotor area. Functionally, these areas are associated with aiming conditions in which the motor execution demands are high (i.e., coordination of rapid reversals) and precise trajectory planning is minimal. These same areas showed significant increases or decreases, respectively, when contrast means were compared with the use of movement time or relative acceleration time, respectively, as the weighting factor. A functional dissociation resulted from the weighted linear contrasts between larger (limb transport) or smaller (endpoint targeting) type amplitude/target width aiming conditions. Areas with significantly greater rCBF for targeting were the left motor cortex, left intraparietal sulcus, and left caudate. In contrast, those areas with greater rCBF associated with limb transport included bilateral occipital lingual gyri and the right anterior cerebellum. Various theoretical explanations for the speed/accuracy tradeoffs of rapid aiming movements have been proposed since the original information theory hypothesis of Fitts.This is the first report to relate the predictable variations in motor control under changing task constraints with the functional anatomy of these rapid goal-directed aiming movements. Differences in unimanual aiming task difficulty lead to dissociable activation of cortical-subcortical networks.Further, these data suggest that when more precise targeting is required, independent of task difficulty, a cortical-subcortical loop composed of the contralateral motor cortex, intraparietal sulcus, and caudate is activated. This is consistent with the role of motor cortex for controlling direction of movement on the basis of population encoding.