Visual/Spatial Properties of Posterior Parietal Neurons

描述(摘自申请者的摘要)：虽然顶骨后 长期以来，大脑皮层(PPC)一直被认为是 空间意识和空间注意力的不同感觉模式， 最近的研究指出了这一领域的另一个非常重要的作用 在运动计划方面。一个重要的进步是发现了 PPC内不同区域的意图解剖图 专门针对不同的行为。在目标1中，我们将确定 在行动规划中，这些领域中的一些领域之间的相互关系。在……里面 特别是，我们将检查区域LIP是否在决策中起执行作用 导致眼睛和肢体运动，或者如果嘴唇主要参与 前者为MIP区，后者为5区。 另一个重要的进展是阐明了空间 在一些PPC皮质区的表达。这些结果导致了一个普遍的 建议将行动计划的早期阶段放在 在灵长类动物中，以眼睛为中心的坐标，无论感觉输入或 最终的马达产量。然而，许多PPC神经元的活动是获得的 受眼睛、头部和四肢位置的调节。目标2将检查这些购买力平价 “增益场”可能会影响眼睛和手部动作的决定。 经典地说，人们一直认为， 从目标物体从视网膜到视网膜的转换达到结果 物体坐标，然后减去物体在 身体坐标-从手的位置生成身体坐标 肢体坐标中的运动误差。我们发现早期的运动计划 在PPC中的眼睛坐标中出现建议了另一种方案，其中 手用眼睛坐标表示，并从位置减去 目标物在眼睛中坐标以产生电机误差信号。我们将测试 目标3中的这个新想法。最后，在目标4中，我们将检查空间 提供输入的听觉区域中声音位置的表示，TPT 给PPC。这些实验被设计用来确定听觉的阶段 以头部为中心的听野转换为 与PPC中遇到的类似的以眼睛为中心的听觉区域。

DESCRIPTION (From the Applicant's Abstract): Although the posterior parietal cortex (PPC) has long been appreciated to be an area for association of different sensory modalities for spatial awareness and for spatial attention, recent studies have pointed to an additional, and very major, role of this area in movement planning. One important advance has been the fmding that there is an anatomical map of intentions within the PPC, with different areas specialized for different behaviors. In Aim 1 we will determine the inter-relationship between some of these areas in movement planning. In particular, we will examine whether area LIP has an executive role in decision making for both eye and limb movements, or if LIP is primarily involved in the former, and areas MIP and 5 in the latter. Another important advance has been the elucidation of the spatial representations in some PPC cortical areas. These results have led to a general proposal that the early stages of movement planning are performed in eye-centered coordinates in primates, regardless of the sensory input or eventual motor output. However, the activity of many PPC neurons is gain modulated by eye, head and limb position. Aim 2 will examine whether these PPC "gain fields" may effect the decisions to make eye and hand movements. Classically it has been believed that the coordinate transformation for reaching results from the transformation of the traget object from retinal to body coordinates, and then the subtraction of the object location in body-coordinates from the location of the hand in body coordinates to generate the motor error in limb coordinates. Our finding that early movement planning occurs in eye-coordinates in PPC suggests an alternative scheme, in which the hand is represented in eye coordinates and is subtracted from the location of the target in eye coordinates to produce the motor error signal. We will test this new idea in aim 3. Lastly, in aim 4 we will examine the spatial representation of sound location in an auditory area, Tpt, that provides input to the PPC. These experiments are designed to determine the stage in auditory processing pathway where head-centered auditory fields are converted into eye-centered auditory fields similar to those encountered in the PPC.