Active Touch: Vibrissal Tactile Discrimination in the Rat

感官输入通常可以通过特定的看、听、闻或感觉的行为来增强。啮齿动物有很大的面部胡须，即触须，用来通过触摸来观察物体。对啮齿动物触觉系统的解剖学和生理学研究已经研究了感觉整合的细胞机制和经验在发育过程中的作用，特别是与大脑的躯体感觉皮质有关的机制。触须本身的感觉能力通常是从去除胡须后看到的严重缺陷中推断出来的，但人们对这些毛发检测或区分各种自然刺激的能力知之甚少。这个项目使用了一种新的方法来确定如何在行为中使用触觉来进行复杂的触觉辨别。蒙眼的动物将接受训练，以辨别经过校准的粗糙表面；有证据表明，啮齿动物至少可以像灵长类动物那样用指尖辨别触须。基于视频的分析将量化幅度、频率、速度以及胡须运动和头部运动的关系。感官输入在发育过程中的作用将通过修剪一排排新生大鼠的胡须直到它们45天大小，然后允许胡须生长来测试。众所周知，这种操作会在大脑的躯体感觉皮质产生异常，并预计会在成年人中产生辨别缺陷。行为策略将在正常和新生儿缺乏的动物之间进行比较，看看胡须运动是如何被用来区分的，以及是否学习了新的策略。最后，将研究胡须与表面的相互作用，并将搅拌的时间模式与躯体感觉皮质神经细胞中看到的兴奋和抑制的时间进行比较。这些新颖的研究将填补我们将大脑功能与触觉行为联系起来的知识的一个关键空白；结果不仅将对体感科学产生重大影响，而且将对感觉科学和神经生物学以及学习和行为研究产生重大影响。

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.