Influence of modafinil on somatosensory input processing in the human brain-stem.

Objective: Since high frequency oscillations (HFOs) evoked by upper limb stimulation are susceptible to arousal fluctuation, we verified whether administration of modafinil, a vigilance promoting drug, modifies such responses at different levels of the somatosensory system.

Methods: HFOs were obtained in 6 healthy volunteers by 500-700 Hz filtering of right median nerve somatosensory evoked potentials, before and 2 hours after the administration of 100 mg modafinil. Raw data were further submitted to brain electrical source analysis.

Results: Modafinil significantly increased subcortical HFOs, as well as the strength of a dipolar source at the base of the skull.

Conclusions: Our data suggest that modafinil exerts its action also at the level of the brain-stem, where it interferes with the processing of somatosensory ascending inputs.