PDF(Pubmed)
Abstract：
Juggling is a very complex activity requiring motor, visual and coordination skills. Expert jugglers experience a \"third eye\" monitoring leftward and rightward ball zenith positions alternately, in the upper visual fields, while maintaining their gaze straight-ahead. This \"third eye\" reduces their motor noise (improved body stability and decrease in hand movement variability) as it avoids the numerous head and eye movements that add noise into the system and make trajectories more uncertain. Neuroimaging studies have shown that learning to juggle induces white and grey matter hypertrophy at the posterior intraparietal sulcus. Damage to this brain region leads to optic ataxia, a clinical condition characterised by peripheral pointing bias toward gaze position. We predicted that expert jugglers would, conversely, present better accuracy in a peripheral pointing task. The mean pointing accuracy of expert jugglers was better for peripheral pointing within the upper visual field, compatible with their subjective experience of the \"third eye\". Further analyses showed that experts exhibited much less between-subject variability than beginners, reinforcing the interpretation of a vertically asymmetrical calibration of peripheral space, characteristic of juggling and homogenous in the expert group. On the contrary, individual pointing variability did not differ between groups neither globally nor in any sector of space, showing that the reduced motor noise of experts in juggling did not transfer to pointing. It is concluded that the plasticity of the posterior intraparietal sulcus related to juggling expertise does not consist of globally improved visual-to-motor ability. It rather consists of peripheral space calibration by practicing horizontal covert shifts of the attentional spotlight within the upper visual field, between left and right ball zenith positions.
摘要：
杂耍是一项非常复杂的活动，需要运动，视觉和协调能力。专家杂耍者体验“第三只眼”交替监视左右球的天顶位置，在上面的视野中，同时保持他们的目光直视前方。这种“第三只眼睛”减少了它们的运动噪音（改善了身体稳定性并减少了手部运动的可变性），因为它避免了大量的头部和眼睛运动，这些运动会增加系统中的噪音并使轨迹更加不确定。神经影像学研究表明，学习杂耍会在后顶内沟引起白质和灰质肥大。这个大脑区域的损伤会导致视神经共济失调，以周围指向注视位置为特征的临床状况。我们预测，杂耍专家会，相反,在外围指向任务中呈现更好的准确性。专家杂耍者的平均指向精度对于上视野内的外围指向更好，与他们的“第三只眼睛”的主观体验相兼容。进一步的分析表明，专家表现出的受试者之间的变异性比初学者少得多，加强对外围空间垂直不对称校准的解释，在专家组中具有杂耍和同质的特点。相反,个人指向变异性在全球或任何空间领域都没有不同的群体之间，表明杂耍专家减少的电机噪音并没有转移到指向。结论是，与杂耍专业知识相关的后顶内沟的可塑性并不包括全球改善的视觉运动能力。它由外围空间校准组成，通过在上视野内练习注意聚光灯的水平隐蔽移动，在左右球天顶位置之间。
