Functional architecture of motor cortex: Topography and connections

描述(申请人提供)：本提案的目的是提高我们对运动皮质组织的了解。哺乳动物的运动皮质是以一种粗略的躯体定位模式组织起来的，后肢的肌肉位于内侧，前肢和面部的肌肉逐渐向更侧的方向表示。然而，精细的体位移植是杂乱无章的，其原因尚不清楚。例如，在前肢表示中，手指、手和手臂混合在一起并多次出现。这与初级躯体感觉皮质的精细体感形成了鲜明对比。最近对灵长类动物的研究提出了额外的组织原则，与大规模的体位术一起，可能更完整地解释了运动地形图。运动皮质的另一种组织特征是一种明显的空间地图，手被皮质内微刺激驱动到该空间地图(运动终点地图)。无论手的初始位置如何，刺激前肢区域的内侧部位会将手推向脚部附近的位置，而刺激外侧部位的位置会将手推向靠近头部的位置。第二个可选的组织特征是由多个子区域拼凑而成，每个子区域代表一个复杂的、与行为相关的运动，例如进食或退缩(行为学的子区域图)。我建议在两个非灵长类物种中测试这些替代品，以确定它们中的任何一个是否是哺乳动物的一般组织原则。其具体目的是：1.结合连接、构筑、微刺激和感觉定位数据，确定浣熊(Procyon Lotor)运动和感觉运动区的组织和连接。(这个目标已经在松鼠身上完成了)。2.测定加州地松鼠(Spermophilus Beecheyi)和浣熊运动皮质的运动地形图和特殊联系。通过刺激在M1前肢表征中唤起的运动类型的模式将被分析以寻找在猴子运动皮质中看到的相似性或组织。与特定部位的连接将与微刺激结果有关。这些来自特定刺激点的数据将被用来加强或驳斥对复杂刺激诱发运动的功能解释。公共卫生相关性对大脑组织的基本了解是开发诊断和治疗大脑损伤和疾病的新方法的第一步。这项提议旨在提高人们对大脑如何连接和控制肌肉的理解。

DESCRIPTION (provided by applicant): The goal of this proposal is to improve our understanding of motor cortex organization. Motor cortex in mammals is organized in a rough somatotopic pattern, with the muscles of the hindlimb represented medially and the muscles of the forelimb and face represented progressively more laterally. Fine somatotopy is jumbled, however, and the reason for this is not clear. For example, within the forelimb representation, finger, hand, and arm are intermingled and appear multiple times. This contrasts with the fine somatotopy of primary somatosensory cortex. Recent studies in primates have suggested additional organizing principles that, together with large-scale somatotopy, may account more completely for motor topography. One alternative organizational feature in motor cortex is an apparent map of space to which the hand is driven by intracortical microstimulation (movement endpoint map). Regardless of initial hand position, stimulation of medial sites within the forelimb region drives the hand to locations near the feet, whereas stimulation at lateral sites drives the hand to locations near the head. A second alternative organizational feature is a patchwork of subregions, each representing a single complex, behaviorally relevant movement, such as feeding or flinching (ethological subregions map). I propose to test these alternatives in two non-primate species to determine whether either is a general organizing principle in mammals. The specific aims are to: 1. Determine the organization and connections of motor and sensorimotor areas in the raccoon (Procyon lotor) using combined connectional, architectonic, microstimulation, and sensory mapping data. (This aim has been completed in squirrels). 2. Determine the movement topography and specific connections of motor cortex in California ground squirrels (Spermophilus beecheyi) and raccoons. The pattern of movement types evoked in the M1 forelimb representation by stimulation will be analyzed for similarities or organizations seen in monkey motor cortex. Connections to specific sites will be related to microstimulation results. These data from specific stimulation sites will be used to reinforce or refute functional interpretations of complex stimulation-evoked movements. PUBLIC HEALTH RELEVANCE A basic understanding of brain organization is the first step toward developing new ways to diagnose and treat brain damage and disease. This proposal aims to improve the understanding to how the brain connects to and controls muscles.