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的熟练行为。我们的目标是 了解双手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。我们对早期的 双手动作的规划，以及后顶叶皮层中的角色效应器特定区域在其中发挥作用， 规划我们假设区域间和半球间的交流对高血压是必要的 协同例如，顶骨到达区域（PRR）主要控制对侧臂。 可以说，一方面要知道另一方面在做什么，就需要在每个区域的PRR之间交换信息。 半球 这种通讯最直接的途径是通过胼胝体，一个主要的纤维束连接 两个半球。胼胝体的相对可及性为因果检验提供了机会， 胼胝体在HEH协调中所起的作用，以及一般的半球间通信的作用。 利多卡因注射可以可逆地阻断胼胝体特定部位的传导， 和神经元活性可以在阻断之前、期间和之后在行为动物中进行比较。我们预测 当胼胝体内的特定纤维束被阻塞时，HEH协调将受损， 将是负责行为的大脑区域内的神经元相关损伤。 我们的第一个目标是确定胼胝体中特定轴突束的交叉点，并验证我们可以 可逆地阻断通过这些通路的传导。接下来，对于我们的第二个目标，我们将测试特定的假设 当特定的途径被阻断时，哪些行为会受到影响。我们将考虑各种途径， 从顶叶到达区（PRR）和外侧顶叶内区（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，检查PRR和LIP内的活动，以确定神经元回路的特异性 受到特定胼胝体通路短暂丧失的影响。 双手HEH协调对正常人类行为至关重要，但涉及的神经元回路仍然存在。 大部分未知。这项工作将极大地扩展我们对顶叶皮层如何实现复杂但 身体各部分的灵活协调。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肢， 协调模式和协调现有的四肢和眼睛的运动。此外，我们将学习 关于胼胝体在大脑中作用的基本事实。最后，这项工作将阐明 跨大脑区域的远程通信的一般问题，以及这种通信如何与大脑相关 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.