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躯体位置模式组织，后肢的肌肉在内侧，前肢和面部的肌肉逐渐在外侧。然而，精细的躯体形态是混乱的，原因尚不清楚。例如，在前肢表示中，手指、手和手臂混合并出现多次。这与初级躯体感觉皮层的精细躯体特征形成对比。最近对灵长类动物的研究表明，其他组织原则，连同大规模的躯体解剖学，可能会更完整地解释运动地形。运动皮层的另一个组织特征是一个明显的空间图，手被皮层内微刺激驱动（运动终点图）。无论初始手位置如何，前肢区域内的内侧部位的刺激将手驱动到脚附近的位置，而外侧部位处的刺激将手驱动到头部附近的位置。第二种组织特征是由子区域拼凑而成，每个子区域代表一个复杂的、与行为相关的运动，比如进食或退缩（行为学子区域图）。我建议在两个非灵长类物种中测试这些替代方案，以确定其中一个是否是哺乳动物的一般组织原则。具体目标是：1.确定的组织和连接的运动和感觉运动领域的浣熊（南河龙）使用相结合的连接，架构，微刺激，和感觉映射数据。(This目标已在松鼠中完成）。2.确定加州地松鼠和浣熊运动皮层的运动地形图和特定连接。通过刺激在M1前肢表征中诱发的运动类型的模式将被分析在猴运动皮层中观察到的相似性或组织。与特定部位的连接将与微刺激结果相关。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。该提案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.