Some functional observations related to the N18 component of the median nerve SEP.

This work describes the results of two experimental procedures related to the short latency median nerve somatosensory evoked potentials. In the first one, it was possible to show that there is a different rate of increase in the amplitude of the different components related to different intensities of stimulation. In the second one, the simultaneous stimulation of the median and the ulnar nerves disclosed an occlusive interaction which was larger for the N18 than for the other components. These results may be a support to the hypothesis that the N18 component generator is related to the mechanism of presynaptic inhibition within the cuneiform nucleus.