SOMATOSENSORY CORTEX & THALAMUS

我们的目标是研究在人类和非人类灵长类动物中，躯体感觉系统对复杂的灵长类行为的贡献，如手动灵巧、双手的双边协调、多模式整合和目标定向实现所需的感觉运动整合。人类这些能力的进化与我们感觉和运动系统的进化交织在一起。为了了解这些复杂的行为是如何产生的，我们必须揭示我们感觉系统的组织细节，以及为复杂功能服务的神经回路。对外侧沟(LS；SII、PV、VS、7b和RL)皮质场的研究表明，它们参与了触觉辨别、触觉识别、注意以及单、双侧手输入的整合。顶叶后皮质(PP；5区、7a区、LIP区和VIP区)参与产生定向运动、注意力和多模式整合的运动坐标。我们的研究旨在揭示猴大脑皮层区域的地形图组织、感受野大小、刺激偏好以及LS和PP区域的详细地形图连接模式，并确定人类是否也存在类似的区域。我们的建议结合了几种数据收集技术。在非人类灵长类动物中，我们将从LS和PP皮质区域的神经元簇进行细胞外记录，以响应可量化的、可重现的刺激，例如手无毛表面的小凹痕、毛发移位、沿手无毛表面不同方向的轻划、压力、肌肉操作以及手指、手腕和手的运动。在其中一些猴子身上，通过将解剖示踪剂放置到电生理定义的分区中，然后使用多单位电生理记录技术绘制目标结构图，将确定皮质内、穹隆和丘脑连接的详细模式。最近，人们已经证实，功能磁共振成像技术可以在人类身上有效地用于确定区域的地形组织和皮质区域内的细分数量。在我们对猴子进行电生理和连接研究的同时，我们将利用功能磁共振技术来探索人类新皮质的类似区域。我们的刺激选择和感兴趣的领域将以我们在猴子身上的结果为指导。因此，我们将从上面描述的刺激开始，并将我们的努力指向LS和PP皮质的区域。将我们猴子模型中建立的大脑皮层区域和连接模式的框架应用于人类，我们可以扩展我们的刺激指令库，包括更复杂的任务，包括双边操作、目标定向到达和多模式整合。这项研究是将人类和非人类灵长类动物研究结果结合起来的最早努力之一，并有望提供对体感皮质及其对高级知觉和认知加工的贡献的更丰富的理解。

Our goal is to examine in human and non-human primates, the contribution of the somatosensory system to complex primate behaviors such as manual dexterity, bilateral coordination of the hands, multimodal integration, and sensorimotor integration required for goal directed reaching. The evolution of these abilities in humans is intertwined with the evolution of our sensory and motor systems. In order to understand how these sophisticated behaviors are generated, we must uncover the details of the organization of our sensory systems, and the neural circuitry that subserves complex functions. Studies of cortical fields in the lateral sulcus (LS; SII, PV, VS, 7b, and RL) indicate that they are involved in tactile discrimination, tactile recognition, attention, and integration of unilateral and bilateral inputs across the hands. Areas in posterior parietal cortex (PP; areas 5, 7a, LIP and VIP) are involved in generating motor coordinates for directed movements, attention, and multimodal integration. Our studies are aimed at uncovering the topographic organization of cortical fields, receptive field size, stimulus preference, and detailed topographic connection patterns of fields in LS and PP in monkeys, and determining if similar fields exist in humans. Our proposal combines several data collection techniques. In non-human primates we will record extracellularly from clusters of neurons in cortical fields in LS and PP in response to quantifiable, reproducible stimuli such as small indentations on the glabrous surface of the hand, displacement of hairs, light strokes along the glabrous surface of the hand in different directions, pressure, muscle manipulation, and digit, wrist and hand movements. In some of these same monkeys, the detailed patterns of intracortical, callosal, and thalamic connections will be determined by placing anatomical tracers into electrophysiologically defined subdivisions, and then mapping target structures using multiunit electrophysiological recording techniques. Recently, it has been established that the fMRI technique can be used effectively in humans to determine the topographic organization of fields, and the number of subdivisions within a region of cortex. In parallel with our electrophysiological and connection studies in monkeys, we will utilize fMRI techniques to explore similar regions of the neocortex in humans. Our stimulus selection and areas of interest will be guided by our results in monkeys. Thus, we will begin with stimulation like that described above, and direct our efforts to areas in the LS and PP cortex. Applying the framework of cortical fields and patterns of connections established in our monkey model to humans, we can expand our stimulus repertoire to include more sophisticated tasks which involve bilateral manipulation, goal directed reaching, and multimodal integration. This study represents one of the first efforts to combine results from human and non-human primate studies, and promises to provide a richer understanding of somatosensory cortex, and its contribution to higher perceptual and cognitive processing.