An indication for spatial integration in a non-Pacinian mechanoreceptor system?

It is generally accepted that threshold sensitivity for cutaneous vibrational stimuli has a Pacinian component and a non-Pacinian component. While the Pacinian receptor system exhibits spatial integration, such a property has, until now, not been found in any of the non-Pacinian systems. The present measurements of vibration sensitivity for stimuli with spatial contrast in six subjects revealed that at low frequencies (20-80 Hz) the threshold for a matrix of tiny pins is 13 dB lower than the threshold for a single pin, thus suggesting spatial integration in at least one class of non-Pacinian receptors. It is remarkable that the low threshold for matrix stimuli was found under the condition that adjacent rows of pins vibrated with opposite phase while the threshold for a matrix of pins all vibrating with equal phase was similar to the threshold for a single vibrating pin.