FUNCTIONAL ORGANIZATION OF THE SOMATOSENSORY SYSTEM

拟议的综合、系统水平的体感研究解决了三个主要目标。1)我们将确定在感觉传入的重大损失后，灵长类动物发育和成熟的躯体感觉系统如何重组。在一项初步研究中，我们证明猴子的背柱损伤会导致躯体感觉皮质的中度到大规模重组。在一系列新的实验中，周围神经传入的分支将随着它们在脊髓背柱的上升而被切断，并将在完全或不完全移除手部传入后在皮质和皮质下水平研究重组和重组机制。新生儿的损伤预计会导致更广泛的恢复，可能还会有不同的恢复。预计部分节段将导致更快、更有功能的恢复。评估过程包括从长期植入的微电极进行最先进的多点记录。2)相关实验将研究3b区手部皮质部分或完全损伤后的皮质组织。对于这两种类型的研究，将评估改变的神经元的反应特性，以及行为损伤和恢复。新连接的生长和组织化学变化在恢复过程中的作用也将被研究。3)我们计划通过确定我们实验室中发现的体感皮质的两个区域PV和VS的连接，并将这些连接与同一动物的其他区域的连接进行比较，来推进我们对灵长类体感系统功能组织的基本理解。此外，我们将比较猴子、黑猩猩和人类的躯体感觉和运动皮质的化学结构，以帮助确定人类皮质的有效细分，并揭示人类的专门化。这三种类型的研究将提供a)了解发育和成熟的体感系统的可塑性的范围和机制，以指导人类的治疗计划，以及b)更详细和全面地了解灵长类动物的体感系统的组织，这与人类特别相关，并为未来的研究提供指导。

The proposed integrative, systems level somatosensory research addresses three major goals. 1) We will determine how the developing and mature somatosensory systems of primates reorganize after major losses of sensory afferents. In a preliminary study, we demonstrated that dorsal column lesions in monkeys result in a moderate to massive reorganization of somatosensory cortex. In a series of new experiments, branches of peripheral nerve afferents will be cut as they rise in the dorsal columns of the spinal cord, and reorganizations and mechanisms of reorganization will be studied at cortical and subcortical levels after complete or incomplete removals of hand afferents. Lesions in newborns are expected to lead to more extensive and possibly different recoveries. Partial sections are expected to lead to more rapid and more functional recoveries. Evaluation processing include state-of-the-art multisite recordings from chronically implanted microelectrodes. 2) Related experiments will investigate cortical organization after partial or complete lesions of hand cortex in area 3b. For both types of studies, the response properties of altered neurons, and behavioral impairments and recoveries will be evaluated. The roles of the growth of new connections and histochemical changes in recovery will also be studied. 3) We plan to advance our basic understanding of the functional organization of the somatosensory system of primates by determining the connections of two areas of somatosensory cortex, discovered in our laboratory, PV and VS, and compare these connections with those of other areas in the same animals. In addition, we will compare the chemorchitecture of somatosensory and motor cortex in monkeys, chimpanzees, and humans to help identify valid subdivisions of cortex in humans and reveal human specialization. These three types of studies will provide a) an understanding of the scope and mechanisms of plasticity in the developing and mature somatosensory system that can guide programs of therapy in humans, and b) a more detailed and comprehensive understanding of the organization of the somatosensory system in primates that is especially relevant to humans and as a guide for future research.