Multi-finger Receptive Field Properties in Primary Somatosensory Cortex: A Revised Account of the Spatio-Temporal Integration Functions of Area 3b

AO_SCPLOWBSTRACTC_SCPLOWThe leading view in the somatosensory system indicates that area 3b serves as a cortical relay site that encodes cutaneous (tactile) features limited to individual digits. Our recent work argues against this model by showing that cells in area 3b integrate information from cutaneous and proprioceptive modalities. Here, we further test this model, by studying the multi-finger neural integration properties of area 3b. In contrast to the prevailing view, we found that most cells in area 3b have a receptive field (RF) that extends to multiple digits. Responses to tactile stimulation emerged earlier in cells with a multi-digit (MD) vs. single-digit (SD) RF. We also found that the RF size of MD cells (the number of responsive digits) increased across time, and the orientation preference across digits was highly correlated. Taken together, these data provide strong evidence that area 3b plays a larger role in generating neural representations of tactile objects, as opposed to just being a feature detector relay site.