Neural basis of limb selection in unimanual reaching

这个建议的中心目标是了解神经系统的决定， 使用左手或右手1-这是一个简单的选择，是我们日常功能的核心。这里我们关注顶骨 肢体选择机制尽管这是日常行为中最常见的决定之一， 决策过程中一个很大程度上被忽视的方面是决定用哪只手来实现目标。比如说， 当决定进入房间时用哪只手打开电灯开关时， 因素这些因素包括每只手已经在做什么（例如，拿着电话），每只手的距离 到交换机，以及未来的目标（例如，希望随后用特定的手拾取物体）。我们长久以来- 学期目标是阐明肢体选择和运动协调的基本机制。 由于肢体选择存在于大多数行为中，这项工作将提供广泛适用于运动的见解。 控制后顶叶皮层（PPC）是已知的参与规划和控制的行动，在一个 效应器特定方式。一个新兴的概念是，参与运动的相同PPC区域 准备和控制也参与动作选择。我们最近证明了顶骨区域 已知有助于手臂运动的规划，并被称为“顶骨伸展区”（PRR），代码 空间目标到达对侧手臂，但从同侧手臂接收关于同侧手臂的信息。 相反的半球。PRR还与到达与扫视到空间的决定有关。 目标在我们的第一个目标中，我们描述了肢体选择行为，并确定了驱动肢体选择的因素。 选择.在我们的第二个目标中，我们检验了PRR参与单手操作时肢体选择的假设。 到达。接下来，我们研究作为肢体选择功能的半球间沟通。最后运用 可逆性失活的胼胝体纤维连接PRR在每个半球，以确定的作用， 大脑半球间的竞争决定使用哪一个肢体。总体而言，这些研究将具有广泛的 通过阐明PPC和胼胝体连接在基本选择运动中的作用， 行为本研究结果将为进一步探讨较大的双侧额顶叶奠定基础 参与调度的网络。这项工作可以为患有糖尿病的患者提供康复方法。 神经系统疾病，包括中风和创伤性脑损伤，其中肢体使用受到影响。 1我们将交替使用肢体、手臂和手这三个术语。

Abstract The central goal of this proposal is to understand the neural systems subserving the decision to use the left or right hand1 – a simple choice that is central to our daily functions. Here we focus on parietal mechanisms of limb selection. Despite it being one of the most common decisions faced in everyday behavior, a largely neglected aspect of decision making is deciding which hand to use to achieve a goal. For instance, when deciding which hand to use to flip a light switch upon entering a room, the choice is influenced by many factors. These factors include what each hand is already doing (e.g, holding a phone), proximity of each hand to the switch, and future goals (e.g., desire to subsequently pick up an object with a particular hand). Our long- term goals are to elucidate the fundamental mechanisms of limb selection and movement coordination. Because limb selection is present in most behaviors, this work will provide insights broadly applicable to motor control. The posterior parietal cortex (PPC) is known to be involved in the planning and control of actions in an effector-specific manner. An emerging concept is that the same PPC regions that are involved in movement preparation and control also participate in action selection. We recently demonstrated that a parietal region known to contribute to the planning of arm movements and dubbed “the parietal reach region” (PRR), codes the spatial targets for reaches with the contralateral arm but receives information about the ipsilateral arm from the opposite hemisphere. PRR has also been implicated in the decision to reach versus saccade to a spatial target. In our first aim, we characterize limb selection behavior and determine the factors that drive limb selection. In our second aim we test the hypothesis that PRR is involved in limb selection during unimanual reaching. Next, we examine interhemispheric communication as a function of limb choice. Finally, we use reversible inactivation of the callosal fibers connecting PRR in each hemisphere to determine the role of interhemispheric competition in determining which limb to use. Collectively, these studies will have a broad impact on the field by illuminating the roles of PPC and callosal connections in a fundamental choice motor behavior. The results will lay the foundation for future studies that probe the larger bilateral frontoparietal network involved in movement control. The work may inform rehabilitation approaches for patients with neurological disorders including stroke and traumatic brain injuries in whom limb use is affected. 1 We will use the terms limb, arm, and hand interchangeably.