Sensation evoked by simultaneous electrical stimulation of two single mechanoreceptor units

Two tungsten microelectrodes were inserted percutaneously at two points on the forearm of awake human subjects into the median nerve and adjusted so that the activity of each single mechanoreceptor unit could be recorded. After identifying the types of units, the properties of the sensation evoked by simultaneous electrical stimulation were investigated by comparing them with those of the individual stimuli from the electrodes. To date, experiments have been done on the combination of two SAI units whose receptive fields did not overlap. For this combination, no “phantom sensation” was observed. The evoked sensation was the simple sum of those evoked by the individual stimuli. We are now experimenting with other combinations of units