Sensory computations in the cuneate nucleus of macaques

In primates, the responses of individual neurons in primary somatosensory cortex (S1) reflect convergent input from multiple classes of nerve fibers and are selective for behaviorally relevant stimulus features. The conventional view is that these response properties reflect computations that are effected in cortex, implying that sensory signals are not meaningfully processed in the two intervening structures - the Cuneate Nucleus (CN) and the thalamus. To test this hypothesis, we recorded the responses evoked in CN to a battery of stimuli that have been extensively used to characterize tactile coding, including skin indentations, vibrations, random dot patterns, and scanned edges. We found that CN responses are more similar to their S1 counterparts than they are to their inputs: CN neurons receive input from multiple sub-modalities, have spatially complex receptive fields, and exhibit selectivity for geometric features. Thus, CN plays a key role in the processing of tactile information.