Functional architecture of motor cortex: Topography and connections

描述（由申请人提供）：本提案的目标是提高我们对运动皮层组织的理解。哺乳动物的运动皮层以粗略的体位模式组织，后肢肌肉向内侧分布，前肢和面部肌肉逐渐向外侧分布。然而，精细的躯体解剖是混乱的，其原因尚不清楚。例如，在前肢的表现中，手指、手和手臂是混合在一起的，并且多次出现。这与初级体感觉皮层的精细躯体解剖形成对比。最近对灵长类动物的研究提出了其他的组织原则，连同大规模的躯体解剖，可能更全面地解释运动地形。运动皮层的另一个组织特征是明显的空间图，手是由皮层内微刺激驱动的（运动端点图）。无论初始手的位置如何，前肢区域内的内侧部位的刺激将手驱动到脚附近的位置，而外侧部位的刺激将手驱动到头部附近的位置。第二个可选的组织特征是小区域的拼凑，每个小区域代表一种复杂的、与行为相关的运动，例如进食或退缩（动物行为学小区域图）。我建议在两种非灵长类动物身上测试这两种选择，以确定这两种选择是否是哺乳动物的普遍组织原则。具体目标是：1。利用连接、结构、微刺激和感觉映射数据，确定浣熊（Procyon lotor）运动和感觉运动区域的组织和连接。（这个目标已经在松鼠身上实现了）。2. 确定加利福尼亚地松鼠和浣熊的运动地形和运动皮层的特定连接。我们将分析刺激引起的M1前肢表征的运动类型模式，以寻找猴子运动皮层的相似性或组织。与特定部位的连接将与微刺激结果有关。这些来自特定刺激部位的数据将用于加强或反驳复杂刺激诱发运动的功能解释。对大脑组织的基本了解是开发诊断和治疗脑损伤和疾病的新方法的第一步。这一建议旨在提高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.