Somatosensory Cortex and Thalamus

描述（由申请人提供）：虽然第5区一直被认为是一个专门处理躯体输入的后顶叶区域，但最近我们实验室在新大陆和旧大陆猴子身上的证据，以及其他实验室的工作表明，这一皮层区域也参与处理视觉输入，并与运动系统密切相关。越来越多的证据表明，第5区可能是一个“中央计划器”，在有意伸手和抓握时监测肢体位置，将感觉位置转换为有意运动的运动坐标，以及在额外的个人空间中感知身体的运动。本研究的目的是确定后顶叶区5在视觉引导和非视觉引导下的伸手和抓握、物体操作、双手的双边协调以及大脑半球间的信息传递中的作用。为了实现这一目标，我们将在猕猴的手部和前臂的5区进行电生理学定向的单侧病变，并检查这些病变对这些行为的影响。我们预计5区消融将导致各种缺陷，包括手的灵巧性，伸手，抓握和双手的双边协调。提出的研究分为三大类实验。第一个系列的实验将检查猕猴的皮层、胼胝体和皮层下的第5区和相邻的体感区2的连接。第二组实验将检查5区精确定位损伤对定向伸手和抓握、双手的双边协调、形状识别能力和半球间转移的影响。任务包括视觉引导和非视觉引导条件下的伸手和抓握、双侧手操作和同侧和双侧手使用条件下的物体识别。最后一系列的实验将通过确定功能组织和解剖皮质连通性的变化是否作为损伤的结果发生在皮质2区，来检查行为恢复的皮质基质。这项研究首次尝试将现代神经解剖学、电生理学和损伤技术结合起来，以确定单个皮质场在产生复杂手部使用中的作用。此外，这是少数利用电生理学和神经解剖学技术来检查皮层损伤后发生的长期皮层变化，随后进行行为训练的研究之一。这些研究最终将使我们更好地了解5区在伸手、抓握、物体操作和双手双边协调中的作用，5区损伤后行为可塑性的时间过程，以及脑损伤后促进恢复的皮质机制。

DESCRIPTION (provided by applicant): While area 5 has been considered a posterior parietal field involved exclusively in processing somatic inputs, recent evidence from our laboratory in both New World and Old World monkeys, as well as work from other laboratories, indicate that this cortical area is also involved in processing visual inputs, and is closely associated with the motor system. Accumulating evidence indicates that area 5 may be a "central planner" critical for monitoring limb location during intended reaching and grasping, converting sensory locations into motor coordinates for intentional movement, and in perceiving the movements of the body in extra personal space. The goal of the present investigation is to determine the role of posterior parietal area 5 in visually guided and non-visually guided reaching and grasping, object manipulation, bilateral coordination of the hands, and information transfer across the' cerebral hemispheres. To accomplish this, we will make electrophysiologically targeted unilateral lesions in the hand and forearm representation of area 5 in macaque monkeys, and examine the effects of these lesions on these behaviors. We expect that ablations of area 5 will result in a variety of deficits involving manual dexterity, reaching, grasping, and bilateral coordination of the hands. The proposed studies are broken into three major groups of experiments. The first series of experiments will examine the cortical, callosal, and subcortical connections of area 5 and adjacent somatosensory area 2, in macaque monkeys. The second group of experiments will examine the consequences of precisely targeted lesions in area 5 on directed reaching and grasping, bilateral coordination of the hands, shape discrimination abilities and interhemispheric transfer. The tasks include reaching and grasping under visually guided and non-visually guided conditions, bilateral manipulation of objects, and object identification under both ipsilateral and bilateral hand use conditions. The final series of experiments will examine the cortical substrate for behavioral recovery by determining if changes in both functional organization and anatomical cortical connectivity have occurred in cortical area 2 as a consequence of the lesion. This study represents one of the first attempts to combine modern neuroanatomical, electrophysiological, and lesioning techniques to determine the contribution of a single cortical field involved in generating sophisticated hand use. Further, it is one of the few studies that utilizes electrophysiological and neuroanatomical techniques to examine the long-term cortical changes that occur after cortical damage, followed by behavioral training. These studies will ultimately allow us to better understand the role of area 5 in reaching, grasping, object manipulation, and bilateral coordination of the hands, the time course of behavioral plasticity following lesions in area 5, and the cortical mechanisms that contribute to recovery after brain injury.