Tactile nerve fibers fall into a few classes that can be readily distinguished based on their spatiotemporal response properties. Because nerve fibers reflect local skin deformations, they individually carry ambiguous signals about object features. In contrast, cortical neurons exhibit heterogeneous response properties that reflect computations applied to convergent input from multiple classes of afferents, which confer to them a selectivity for behaviorally relevant features of objects. The conventional view is that these complex response properties arise within the cortex itself, implying that sensory signals are not processed to any significant extent in the two intervening structures—the cuneate nucleus (CN) and the thalamus. To test this hypothesis, we recorded the responses evoked in the CN to a battery of stimuli that have been extensively used to characterize tactile coding in both the periphery and cortex, including skin indentations, vibrations, random dot patterns, and scanned edges. We found that CN responses are more similar to their cortical counterparts than they are to their inputs: CN neurons receive input from multiple classes of nerve fibers, they have spatially complex receptive fields, and they exhibit selectivity for object features. Contrary to consensus, then, the CN plays a key role in processing tactile information.

触觉神经纤维分为几类，可以根据其时空响应特性轻松区分。由于神经纤维反映局部皮肤变形，因此它们各自携带有关物体特征的模糊信号。相比之下，皮层神经元表现出异质响应特性，反映了应用于来自多类传入神经的汇聚输入的计算，这赋予它们对对象的行为相关特征的选择性。传统观点认为，这些复杂的反应特性出现在皮质本身内，这意味着感觉信号在两个介入结构——楔状核（CN）和丘脑中没有得到任何显着的处理。为了检验这一假设，我们记录了中枢神经系统对一系列刺激的反应，这些刺激已被广泛用于表征外周和皮层的触​​觉编码，包括皮肤压痕、振动、随机点图案和扫描边缘。我们发现，CN 反应与其皮质对应物比与其输入更相似：CN 神经元接收来自多种神经纤维的输入，它们具有空间复杂的感受野，并且对物体特征表现出选择性。与共识相反，CN 在处理触觉信息中发挥着关键作用。