Influence of parameter settings on paired-pulse-suppression in somatosensory evoked potentials: a systematic analysis.

ABSTRACT

OBJECTIVE: Paired-pulse somatosensory evoked potentials (SEPs) are a common tool to investigate excitability in the human somatosensory cortex. Comparing literature about paired-pulse SEP, there is no standard set of stimulation parameters, while little is known about the influence of stimulation parameters on paired-pulse suppression. METHODS: We analyzed changes of paired-pulse ratios by varying repetition rates from 1 to 9Hz, and using stimulus intensities of 250% of the sensory threshold and 100%, 120%, and 140% of the motor threshold, which are most frequently used in studies using paired-pulse SEPs. RESULTS: We found a significant effect of repetition rate on paired-pulse suppression with increasing paired-pulse ratios from 1 to 9Hz, which is mainly caused by a change of single pulse amplitudes. We found no difference in paired-pulse suppression at the tested stimulation intensities. CONCLUSIONS: The extent of paired-pulse ratios across different studies should be interpreted with caution due to the high dependence on repetition rate, while the results at the commonly used stimulus intensities are comparable. SIGNIFICANCE: For an optimized parameter setting with sufficient paired-pulse suppression, we suggest a stimulation rate of 1 or 3Hz and a stimulation intensity of 250% of sensory threshold or slightly above motor threshold.