Sensorimotor loops in vibrissa somatosensation

描述（由申请人提供）：我们在通过大鼠触须的探索性搅动运动完成的物体的触觉定位的背景下解决主动感觉。我们的指导假设是，神经表征跨越封闭的感觉运动回路的基础上的定位对象的积极移动的传感器。过去的工作已经建立了两种形式的触须感觉运动信号，原则上，可以使用的大鼠计算接触和对象定位在头部为中心的坐标。一个是与接触无关的参考信号，当动物主动搅动时，它编码触须角度。第二种形式是一种基于接触的信号，其皮质表示在搅拌，而不是初级神经元的代表性，仍然是清醒的行为动物的特点。我们建议探测传感器位置和传感器接触信息的收敛性。这用于描绘在以头部为中心的坐标中的主动触须触摸的计算和随后的触须的运动控制。我们的计划是在两个层面进行：脑干感觉运动回路和皮质信号。我们要求：脑干水平的反馈提供了相对快速的信号，在指导触须的运动中起着什么作用？这种反馈必然会改变触摸信号的性质，这是由高阶大脑区域处理的。当大鼠触摸目标时，在触须初级感觉（S1）皮层中，它是如何融合触须位置信号和触觉信号的？这种探究可以建立在以头为中心的坐标系中接触的神经表征.在初级运动皮层（M1）中，触须的位置是如何由棘波序列表示的？M1控制触须的运动吗？这些并发的询问可以建立感觉反馈到运动控制的转换。在探索性搅动和触摸过程中，触须S1和M1皮层之间的信号传递的本质是什么？感觉运动控制的研究是理解肌张力障碍的基础，即，运动功能障碍。触须系统的嵌套闭环结构与其他结构相似，如颅肌张力障碍中涉及的三叉神经环和帕金森震颤中涉及的皮质纹状体环。因此，触须系统提供了一个实验性的计算测试床的基本概念，在神经肌肉控制。

DESCRIPTION (provided by applicant): We address active sensation in the context of tactile localization of objects accomplished by exploratory whisking movements of the rat vibrissae. Our guiding hypothesis is that neural representations that span closed sensorimotor loops underlie the localization of objects by actively moving sensors. Past work has established two forms of vibrissa sensorimotor signals that, in principle, can be used by the rat for computing contact and object localization in head-centered coordinates. One is a contact-independent reference signal that codes for vibrissa angle as animals actively whisk. The second form is a contact-based signal whose cortical representation during whisking, as opposed to the representation for primary neurons, remains to be characterized in awake behaving animals. We propose to probe the convergence of sensor position and sensor contact information. This serves to delineate the computation of active vibrissa touch in head-centered coordinates and the subsequent motor control of the vibrissae. Our program is conducted at two levels: that of the brainstem sensorimotor loop and that of cortical signaling. We ask: What is the role of feedback at the level of the brainstem, which provides relatively fast signaling, in directing the motion of the vibrissae? This feedback will necessarily change the nature of a touch signal this is processed by higher-order brain areas. How does the rat fuse signals of vibrissa position with those of touch in vibrissa primary sensory (S1) cortex as it palpates a target? This inquiry can establish the neural representation of contact in head- centered coordinates. How is vibrissa position represented by spike trains in primary motor (M1) cortex and further, does M1 control vibrissa motion? These concurrent inquiries can establish the transformation of sensory feedback into motor control. What is the nature of signaling between vibrissa S1 and M1 cortices during exploratory whisking and touch? Investigations of sensorimotor control are fundamental to the understanding dystonias, i.e., disorders of motor function. The nested, closed loop structure of the vibrissa system parallels other architectures, such as the trigeminal loop involved in the cranial dystonia blepharospam and the corticostriatal loops involved in Parkinsonian tremors. Thus the vibrissa system provides an experimentally accessible computational test- bed for fundamental concepts in neuromuscular control.