Interhemispheric communication underlying bimanual and eye-hand coordination

摘要 灵长类动物，包括人类，擅长协调他们的手臂和眼睛熟练的行为。我们的目标是 了解双指甲协调和眼-手结合的神经回路 协调，我们称之为“手-眼-手”(Heh)协调。我们特别感兴趣的是早期 双手运动的计划，以及顶叶后皮质中角色效应器的特定区域在其中发挥作用 计划。我们假设区域间和半球间的通信对人类是必要的。 协调。例如，顶叶到达区(PRR)主要控制对侧臂。一种方法是 可以说，一只手要知道另一只手在做什么，就是为了在每一只手的PRR之间交换信息 半球。 这种交流最直接的途径是通过胼胝体，这是一条连接 两个半球。相对可及性为因果检验提供了一个机会。 特别是在大脑半球之间的协调中，胼胝体扮演着特殊的角色。 利多卡因注射可可逆性地阻断通过特定部位的胼胝体传导和行为 而且，可以比较封锁前、封锁期间和封锁后动物的神经元活动。我们预测 当痂内的特定fi束被阻塞时，HEH的协调性将受到损害 将与负责行为的大脑区域内的这种损伤的神经元相关。 我们的fi的第一个目标是确定特定轴突束在何方交叉，并验证我们 可逆地阻断通过这些通路的传导。接下来，为了我们的第二个目的，我们将测试特定的fic假设。 当特定的通路被阻断时，哪些行为会受到影响。我们将考虑如何实现 从顶前区(PRR)和外侧顶内区(LIP)，一个类似的区域编码 扫视计划。动物将执行交错的、自然的单手和双手伸展和扫视。我们 然后，在我们的第三个目标中，将检查Prr和LIP内的活动，以确定fic神经元回路的特异性 受特定fic路径一过性丢失的影响。 双手协调对于正常的人类行为是至关重要的，但涉及的神经元回路仍然存在 很大程度上是未知的。这项工作将极大地扩展我们对顶叶皮质如何实现复杂的理解 fl很好地协调身体各部分。该信息将与其他效应器系统中的协调相关， 并将帮助我们设计下一代脑机接口假体，它可以利用自然 协调模式，并与现有的四肢和眼睛运动相协调。此外，我们将了解到 关于胼胝体在大脑中的作用的基本事实。最后，这项工作将揭示 跨大脑区域的远程通信的一般问题，以及这种通信与大脑的关系 功能。

ABSTRACT Primates, including humans, are expert at coordinating their arms and eyes in skillful behavior. Our goal is to understand the neural circuitry that underlies the combination of bimanual coordination and eye-hand coordination, which we call “hand-eye-hand” (HEH) coordination. We are particularly interested in the early planning of bimanual movements, and the role-effector specific areas in the posterior parietal cortex play in that planning. We hypothesize that inter-areal and inter-hemispheric communication is necessary for HEH coordination. For example, the parietal reach region (PRR) controls primarily the contralateral arm. One way for one hand to know what the other is doing, so to speak, is for information to be exchanged between PRR in each hemisphere. The most direct pathway for such communication is through the corpus callosum, a major fiber tract connecting the two hemispheres. The relative accessibility of the corpus callosum provides an opportunity for causal tests of the role callosum plays in particular, and of inter-hemispheric communication in general, in HEH coordination. Lidocaine injections can reversibly block conduction through particular portions of the callosum, and behavior and neuronal activity can be compared in behaving animals before, during and after blockade. We predict that HEH coordination will be impaired when particular fiber tracts within the callosum are blocked, and that there will be neuronal correlates of that impairment within the brain areas responsible for the behavior. Our first Aim is to establish where in the callosum particular axonal tracts cross, and to verify that we can reversibly block conduction through those pathways. Next, for our second Aim, we will test specific hypotheses regarding which behaviors will be affected when particular pathways are blocked. We will consider pathways to and from the parietal reach region (PRR) and the lateral intraparietal area (LIP), an analogous area that codes saccade plans. Animals will perform interleaved, natural unimanual and bimanual reaches and saccades. We will then, in our third Aim, examine activity within PRR and LIP to determine how specific neuronal circuits are impacted by the transient loss of specific callosal pathways. Bimanual HEH coordination is critical for normal human behavior, yet the neuronal circuits involved remain largely unknown. This work will greatly expand our understanding of how parietal cortex achieves complex yet flexible coordination of body parts. The information will be relevant to coordination in other effector systems, and will help us design the next generation of brain-computer interfacing prosthetics that can leverage natural coordination patterns and coordinate with existing limbs and eye movements. Further, we will learn fundamental facts about the role of the corpus callosum in the brain. Finally, this work will shed light on the general issue of long range communication across brain areas, and how this communication is related to brain function.