Somatosensory Cortex: Neural Coding of Shape

Definition

We appreciate object shape information by touch alone. Spatial feature representations, initially carried by populations of slowly adapting type I afferents (SA1s) in the peripheral nervous system, are centrally encoded by neural populations residing in the somatosensory cortex. Cortical neurons function as spatial filters that select out specific object features falling within their receptive fields (RFs) on the skin. This neural selectivity, or tuning, changes across a hierarchy of processing stages spanning primary (S1) and secondary somatosensory (S2) cortices (Fig. 1a). While somatosensory neurons at the first cortical processing stage (area 3b in S1) have small receptive fields and respond to simple contour features like oriented bars and edges, neurons at intermediate and later processing stages (area 2 and S2) respond to stimulation of larger skin regions and are selective for more complex spatial features. In individual neurons and across neural populations,...