[Further observations on the 'primary' somesthetic response in man. Preliminary results]

In six normal subjects cerebral somatosensory potentials evoked by median nerve stimulation at the wrist have been recorded in order to assess whether N20 and P25 components can be related to a single generator dipole. It was found that, at variance with the current literature, such components are due to separate generator dipoles, possibly related to the activity of different cortical structures. Moreover an additional component, chronologically occurring between N20 and P25, was consistently observed.