NEURAL SUBSTRATES FOR CONTROL OF REACHING IN HUMANS

这个项目的目标是定位人类目标导向到达的神经基质。 使用15-O正电子发射断层扫描（PET）进行功能性脑映射，将用于正常人类志愿者局部脑血流量（rCBF）中与任务相关的变化成像，经颅磁刺激（TMS）将用于可逆地破坏执行各种目标达到任务的受试者的选定皮质区域的功能。 虽然运动学习的基板已经被映射在一些细节，更少的是已知的基板在线纠错，长期的感觉运动适应，视觉和动觉控制信号的协调。 有三个具体的目标，对应的问题：具体目标1：划定各自的神经基板的视觉与动觉控制的目标达成。 三个实验将解决这一目标，每个实验有一个单独的受试者组（每个实验10名受试者），使用有针对性的伸手范式，将视觉和动觉目标和轨迹控制分离开来。 Exp. 1.1：视觉与动觉靶向的PET研究和到达的指导。 Exp. 1.2：在线纠错期间视觉与动觉引导的PET研究。 Exp. 1.3：在棱镜适应过程中视觉与动觉轨迹引导的PET研究。具体目标2：确定目标达成过程中在线错误纠正和运动错误诱导的感觉运动适应的神经基质。 四个实验计划，每一个将涉及一组有针对性的达成范式解离在线错误纠正和运动错误引起的感觉运动适应。 Exp. 2.1：在线错误纠正与运动错误诱导的感觉运动适应的PET研究。 Exp. 2.2：运动错误诱导的感觉运动适应的肢体与眼部成分的PET研究。 Exp. 2.3：有意识与阈下在线纠错的PET研究。 Exp. 2.4：经颅磁刺激研究后顶叶对在线纠错的贡献：外显与阈下目标位移以及视觉与动觉引导到达轨迹。具体目标3：目的：探讨目标定向触达过程中知觉失真（感觉失配和传入失配）引起的感觉运动适应的神经机制。 计划进行四项实验。 每一个将涉及一组有针对性的达到范式，分离的三个因素，涉及长期的感觉运动适应：感觉不匹配，reafferance不匹配，和运动错误。 Exp. 3.1：主动与被动棱镜适应的PET研究。 Exp. 3.2：有和没有视觉运动错误的棱镜适应的PET研究。 Exp. 3.3：棱镜适应中认知因素的PET研究。Exp. 3.4：侧前额叶与后顶叶对棱镜适应的影响的TMS研究。

The goal of this project is to localize the neural substrates of target-directed reaching in humans. Functional brain mapping with 15-O positron emission tomography (PET) will be used to image task-related changes in regional cerebral blood flow (rCBF) in normal human volunteers, and transcranial magnetic stimulation (TMS) will be used to reversibly disrupt the functioning of selected cortical areas of subjects performing a variety of targeted reaching tasks. While the substrates of motor learning have been mapped in some detail, much less is known about the substrates of on-line error correction, long-term sensorimotor adaptation, and coordination of visual and kinesthetic control signals. There are three specific aims, corresponding to the issues: Specific Aim 1: To delineate the respective neural substrates for visual versus kinesthetic control of targeted reaching. Three experiments will address this aim, each with a separate group of subjects (10 subjects per experiment), using targeted reaching paradigms that dissociate visual and kinesthetic targeting and trajectory control. Exp. 1.1: PET study of visual versus kinesthetic targeting and guidance of reaching. Exp. 1.2: PET study of visual versus kinesthetic guidance during on-line error correction. Exp. 1.3: PET study of visual versus kinesthetic trajectory guidance during prism adaptation. Specific Aim 2: To identify the neural substrates for on-line error correction and motor error-induced sensorimotor adaptation in targeted reaching. Four experiments are planned and each will involve set of targeted reaching paradigms to dissociate on-line error correction and motor error-induced sensorimotor adaptation. Exp. 2.1: PET study of on-line error correction versus motor error-induced sensorimotor adaptation. Exp. 2.2: PET study of limb versus oculomotor components of motor error-induced sensorimotor adaptation. Exp. 2.3: PET study of conscious versus subliminal on-line error correction. Exp. 2.4: TMS study of posterior parietal contribution to on-line error correction: overt versus subliminal target displacements and visual versus kinesthetic guidance of reaching trajectory. Specific Aim 3: To identify the neural substrates for sensorimotor adaptation induced by perceptual distortions (sensory mismatch and reafference mismatch) during target-directed reaching. Four experiments are planned. Each will involve a set of targeted reaching paradigms that dissociate the three factors implicated in long-term sensorimotor adaptation: sensory mismatch, reafferance mismatch, and motor error. Exp. 3.1: PET study of active versus passive prism adaptation. Exp. 3.2: PET study of prism adaptation with and without visual motor error. Exp. 3.3: PET study of cognitive factors in prism adaptation. Exp. 3.4: TMS study of lateral prefrontal versus posterior parietal effects on prism adaptation.