Operant conditioning of the short-latency cervical somatosensory evoked potential in quadriplegics

Operant conditioning of short-latency cervical somatosensory evoked potentials (CSEP) was demonstrated in five cervical cord injury subjects. Subjects were conditioned to augment the N14 potential, thought to originate from the dorsal column nucleus. Increased N14 potential was associated with an increase in N19 and P22 potentials, and either a decrease (base) or no change (train) in the brachial plexus potential. The N19 potential was correlated with significant reductions in the sensation-twitch (S/T) ratio during conditioning sessions, indexing improved sensation to low-intensity percutaneous stimulation. Moreover, S/T ratios decreased significantly during conditioning sessions, and were reduced significantly relative to initial baseline values. The results do not appear to be associated with trivial mediating influences.