Interlimb Differences in Motor Control and Learning

描述(申请人提供)：利手是神经组织中不对称的一种突出表现，以前被归类为非运动系统中的偏侧化现象，或作为练习的手使用模式的简单影响。该奖项最初阶段的研究提出了一个新的假设，即惯用手反映了一种功能优化过程，通过这种过程，肢体位置和轨迹的控制已经变得专业化。这一理论与其他运动偏侧化的生物学描述不同，它定义了惯用手的控制机制，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，它仍然是投机性的。我们的第一个目标是测试非优势系统在控制肢体位置和姿势方面是否显示出优势，并探索可能支持这些优势的机制。偏侧化反映了一个最优化的过程，这一命题导致了对不同惯用手的受试者的两种预测：第一，左撇子应该表现出与右撇子相似的专门化；第二，混合利手者应该表现出相对较差的运动表现，因为他们没有发展出侧向专门化。这些预测在我们的第二个和第三个目标中得到了检验，这两个目标是对我们的模型的关键测试。我们的第四个目标是研究随年龄增长可能发生的偏侧化变化的含义。众所周知，某些认知功能的偏侧化随着年龄的增长而减少。我们假设，与年龄相关的运动偏侧化的减少可能会导致老年人的协调障碍，这一现象仍然没有完全被理解。为了验证这一观点，我们将研究表征成人寿命的三个年龄段的运动偏侧化。这项拟议的研究对神经侧化理论以及人类健康都具有重要的意义。偏侧化反映了每个半球对不同功能的专门化，这一想法可能解释了同侧大脑半球在控制单侧手臂运动方面的作用，这种影响有很好的文献记录，但还没有被很好地理解。更重要的是，中风导致的单侧大脑半球损伤会产生功能缺陷，限制功能表现，并已被证明反映了运动的偏侧化。拟议的工作应该有助于阐明这些赤字背后的机制。

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.