Functional Anatomy of Visuomotor Learning & Motor Memory

描述(由申请者提供)：众所周知，大多数动作都会随着练习而提高。然而，大脑完成这一任务的方式在很大程度上仍是未知的。功能磁共振成像(FMRI)为认知的大脑机制提供了重要的见解。相比之下，fMRI对运动学习和运动记忆的研究受到空间限制和不必要的头部运动问题的限制。因此，绝大多数运动学习的功能磁共振研究都是研究手指的动作序列。为了克服这些限制，我们开发了一种新颖的MR兼容手腕任务来研究两种类型的运动学习，这两种类型的运动学习会削弱我们准确指向视觉目标的能力：(1)运动技能学习--获得新的肌肉活动模式的能力，从而在不降低速度的情况下提高运动精度。(2)视觉运动适应--将已经学会的肌肉激活模式与新的空间目标联系起来的能力。我们将分别在基线和旋转条件下研究这两种类型的学习。在基线状态下，受试者手腕快速指向屏幕上排列的8个目标。技能是随着练习而减少的运动时间(MT)和终点变异性。在旋转条件下，在相同的目标设置下，被试最初会犯系统性的30°方向错误，并通过适应来减少这些错误。重要的是，我们开发了一种方法，使MT和峰值速度保持恒定，因此任何观察到的大脑激活变化都可归因于学习而不是表现变化。此外，我们还将研究第二天重新学习的神经相关因素，优势手和非优势手之间的差异，运动干扰的机制，以及运动学习在手臂之间的迁移程度。更好地了解大脑半球对运动学习和运动记忆的贡献，将有助于我们深入了解局灶性脑损伤后的康复机制。我们预计我们的方法将在未来的研究中适用于患者。

DESCRIPTION (provided by applicant): It is well known that most movements improve with practice. However, the way the brain accomplishes this remains largely unknown. Functional magnetic resonance imaging (fMRI) has provided significant insights into brain mechanisms of cognition. In comparison, fMRI studies of motor learning and motor memory have been limited by the constrained space and the problem of unwanted head movements. As a result the great majority of fMRI studies of motor learning have investigated sequences of finger movements. To overcome these limitations, we have developed a novel MR-compatible wrist task to study two types of motor learning that undrlie our ability to accurately point to visual targets: (1) Motor skill learning - the ability to acquire new patterns of muscle activity so that movement accuracy increases without a reduction in speed. (2) Visuomotor adaptation - the ability to associate an already learned pattern of muscle activation with a new spatial goal. We will study these two types of learning with a baseline and a rotation condition, respectively. In the baseline condition, subjects make fast uncorrected pointing movements of the wrist to a series of 8 targets arrayed on a screen. Skill is the decrease in movement time (MT) and endpoint variability with practice. In the rotation condition, with the same target set, subjects initially make systematic 30¿ directional errors, which they reduce through adaptation. Importantly, we have developed a method that keeps MT and peak velocity constant so that any observed brain activation changes are attributable to learning and not performance changes. In addition, we will also examine the neural correlates of re-learning on a second day, differences between the dominant and non-dominant hand, mechanisms of motor interference, and degree of transfer of motor learning between arms. A better understanding of hemispheric contributions to motor learning and motor memory will offer insight into mechanisms of recovery after focal brain injury. We anticipate our approach will be applicable to patients in future studies.