Interlimb Differences in Motor Control and Learning

描述（由申请人提供）：偏手性是神经组织不对称的一种突出表现，以前被认为是非运动系统侧化的产物，或者是手部使用习惯的简单影响。该奖项最初阶段的研究提出了一个新的假设，即手性反映了一个功能优化过程，通过这个过程，肢体位置和轨迹的控制已经变得专业化。这一理论与其他关于运动侧化的生物学描述不同，它定义了构成利手性的控制机制，并提出了非优势系统的优势。然而，由于非主导体系专业化的证据有限，它仍然是推测性的。我们的第一个目的是测试非主导系统是否在控制肢体位置和姿势方面表现出优势，并探索这种优势可能背后的机制。偏侧化反映了一个优化过程，这一命题导致了对不同手性受试者的两种预测：第一，左撇子应该表现出与右撇子镜像的专门化，第二，混合手者应该表现出运动表现的相对缺陷，因为他们没有发展出横向专门化。这些预测在我们的第二个和第三个目标中进行了检验，它们是对我们模型的关键检验。我们的第四个目的是研究可能随着衰老而发生的侧化变化的含义。已经确定的是，某些认知功能的偏侧性随着年龄的增长而下降。我们假设，运动侧化的年龄依赖性减少可能会导致老年人的协调缺陷，这一现象仍未完全了解。为了验证这一观点，我们将研究三个年龄组的运动侧化，这些年龄组是成年人寿命的特征。该研究对神经侧化理论以及人类健康具有重要意义。侧化反映了每个半球对不同功能的专门化，这一观点可能解释了同侧半球在控制单侧手臂运动中的作用，这一效应已被充分记录，但尚未得到很好的理解。更重要的是，中风引起的单侧半球损伤会产生同侧缺陷，限制功能表现，并反映运动侧化。拟议的工作应有助于阐明这些缺陷背后的机制。

DESCRIPTION (provided by applicant): Handedness is a prominent manifestation of asymmetry in neural organization that has previously been relegated as either an artifact of lateralization in non-motor systems, or as the simple effect of practiced patterns of hand use. The studies in the initial phase of this award gave rise to a new hypothesis, that handedness reflects a functional optimization process through which control of limb position and trajectory have become specialized. This theory diverges from other biological descriptions of motor lateralization in defining the control mechanisms that underlie handedness, and in proposing advantages for the non- dominant system. However, it remains speculative due to limited evidence for specialization of the non- dominant system. Our first aim tests whether the non-dominant system displays advantages in controlling limb position and posture, and explores the mechanisms that might underlie such advantages. The proposition that lateralization reflects an optimization process leads to two predictions about subjects with varied handedness: First, left handers should show specializations that mirror image those of right handers, and second, mixed handers should exhibit relative deficiencies in motor performance because they have not developed lateral specializations. These predictions are examined in our second and third aims, which serve as critical tests of our model. Our fourth aim examines the implications of changes in lateralization that might occur with aging. It has been well established that lateralization in certain cognitive functions decreases with age. We hypothesize that age-dependent reductions in motor lateralization might give rise to coordination deficits in elderly individuals, a phenomenon that remains incompletely understood. To test this idea, we will examine motor lateralization in three age groups that characterize the adult lifespan. The proposed research has strong implications for neural lateralization theory, as well as for human health. The idea that lateralization reflects specialization of each hemisphere for different functions might explain the role of ipsilateral hemisphere in controlling unilateral arm movements, an effect that is well documented but is not well understood. More importantly, unilateral hemisphere damage due to stroke produces ipsilesional deficits that limit functional performance and that have been shown to reflect motor lateralization. The proposed work should help elucidate the mechanisms that underlie such deficits.