Active Touch: Vibrissal Tactile Discrimination in the Rat

感官输入通常可以通过特定的看、听、嗅或感觉行为来增强。啮齿类动物有很大的面部胡须，即触须，用来通过触摸来调查物体。对啮齿动物振动系统的解剖学和生理学研究已经检验了在发育过程中感觉整合和经验作用的细胞机制，特别是与大脑体感皮层的关系。触须本身的感觉能力通常是从去除须后所见的大体缺陷推断出来的，但很少有人知道这些毛发能在多大程度上探测或区分各种自然刺激。这个项目使用了一种新颖的方法来确定触须是如何在行为中被用来进行复杂的触觉辨别的。蒙住眼睛的动物将被训练以区分校准粗糙度的表面；有证据表明啮齿类动物至少可以像灵长类动物一样用指尖区分触须。基于视频的分析将量化胡须运动和头部运动的幅度、频率、速度和关系。感官输入在发育过程中的作用将通过修剪新生大鼠的成排胡须来测试，直到它们45天大，然后让胡须生长。这种操作已知会在大脑的体感觉皮层中产生异常，并预计会在成人中产生识别缺陷。研究人员将比较正常动物和刚出生时被剥夺权利的动物的行为策略，看看它们是如何利用胡须运动来进行区分的，以及它们是否学会了新的策略。最后，研究人员将研究晶须与表面的相互作用，并将晶须的时间模式与体感皮层中神经细胞的兴奋和抑制时间进行比较。这些新颖的研究将填补我们在触觉行为与大脑功能相关的知识方面的一个关键空白；研究结果将不仅对体感科学，而且对感觉科学和神经生物学，以及学习和行为的研究产生重大影响。

Sensory input often can be enhanced by specific behaviors for looking, listening, sniffing or feeling. Rodents have large facial whiskers, the vibrissae, that are used to investigate objects by touch. Studies on anatomy and physiology of the rodent vibrissal system have examined cellular mechanisms of both sensory integration and the role of experience during development, particularly in relation to the somatosensory cortex of the brain. Sensory capabilities of the vibrissae themselves usually have been inferred from gross deficits seen after whisker removal, but little is known about how well these hairs can detect or discriminate various natural stimuli. This project uses a novel approach to determine how the vibrissae are used in behavior to make sophisticated tactile discriminations. Blindfolded animals will be trained to distinguish between surfaces of calibrated roughness; there is evidence that the rodents can discriminate with vibrissae at least as well as primates using fingertips. Video-based analysis will quantify amplitude, frequency, speed, and relations of whisker movements and head movements. The role of sensory input during development will be tested by trimming rows of whiskers of neonatal rats until they are 45 days old, then allowing whisker growth. This manipulation is known to produce abnormalities in the somatosensory cortex of the brain, and expected to produce discrimination deficits in the adults. Behavioral strategies will be compared between normal and neonatally deprived animals, to see how whisker movements are used to discriminate, and whether new strategies are learned. Finally, the whiskers will be studied as they interact with the surface, and the time patterns of whisking will be compared to the timing of excitation and inhibition seen in nerve cells in the somatosensory cortex. These novel studies will fill a critical gap in our knowledge relating brain function to tactile behavior; results will have a high impact not only on somatosensory science, but on sensory science and neurobiology, and on studies of learning and behavior.