FUNCTIONAL ORGANIZATION OF THE SOMATOSENSORY SYSTEM

提出的综合系统级体感研究有三个主要目标。1)我们将确定灵长类动物发育和成熟的体感觉系统在感觉传入事件重大损失后如何重组。在一项初步研究中，我们证明了猴子背柱损伤导致体感觉皮层的中度到大规模重组。在一系列新的实验中，将切断周围神经传入神经在脊髓背柱上升的分支，并在完全或不完全去除手传入神经后，在皮层和皮层下水平上研究重组和重组机制。新生儿的病变预计会导致更广泛和可能不同的恢复。部分切除有望更快、更有效地恢复。评估处理包括长期植入微电极的最先进的多位点记录。2)相关实验将研究手皮层3b区部分或完全病变后的皮层组织。对于这两种类型的研究，将评估改变神经元的反应特性，以及行为障碍和恢复。新连接的生长和组织化学变化在恢复中的作用也将被研究。3)我们计划通过确定我们实验室发现的两个体感皮层区域PV和VS的连接，并将它们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认识。此外，我们将比较猴子、黑猩猩和人类体感皮层和运动皮层的化学结构，以帮助确定人类皮层的有效细分并揭示人类的专业化。这三种类型的研究将提供a)在发育和成熟的体感系统中可塑性的范围和机制的理解，可以指导人类的治疗方案；b)更详细和全面地了解灵长类动物体感系统的组织，特别是与人类相关的，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.