The relationship between electrode area and sensory qualities in electrical human tongue stimulation

The relationship between the size of the stimulated human tongue area, the stimulating electric current intensity and the provoked sensory qualities was examined. Five different electrode areas and four anodal current intensities were used. The observed sensations were of three kinds: sour taste, somatosensory, and undefined ones. At a given current intensity level the proportion of taste increases with the increase in the stimulation area, while somatosensory sensations decrease. These results imply that at the suprathreshold level there is a certain interdependence between the area, current intensity and sensory effects. In order to achieve optimal activation of the taste system alone, it is more effective to use a larger electrode and stronger current, than to use smaller areas and weaker stimuli: in this case the electrical sour taste is satisfactorily clear, since the somatosensory system is still not activated. These findings may have implications in clinical electrogustometry.