Vertical neuronal arrays in the postcentral gyrus signaling active touch: a receptive field study in the conscious monkey.

Single neuronal activity was recorded in the crown of the postcentral gyrus (areas 1 and 2) in 5 conscious monkeys. A total of 88 penetrations entered perpendicularly to the cortical surface. Among them, 6 examples are chosen and the receptive field characteristics of constituent neurons were described in some detail. Receptive fields of neurons recorded along a particular penetration were variable in their positions, but the largest receptive field usually covered the others. Neurons with the largest receptive fields were found most frequently in the infragranular layers. Often they included inhibitory receptive fields. The inhibitory receptive fields were arranged side-by-side to the excitatory ones, rather than in a center-surround fashion. The key stimulus common to neurons in a vertical penetration was the contact of an object to the receptive field achieved during animal's active behavior to manipulate the object. We thus designated the largest receptive field as a functional surface. Our results demonstrate that a vertical array of neurons in this cortical region can be regarded as a functional assemblage which deals with a set of information concerning one of various aspects of active touch.