The effects of tobacco smoking on the short, middle, and long latency responses of the blink reflex in humans.

The three responses (R1, R2, and R3) of the electrically elicited blink reflex (BR) obtained in four normal human subjects were investigated before and after smoking both a filtered and an unfiltered cigarette. The changes observed in the BR were stronger and statistically more significant for the unfiltered than for the filtered cigarette, (p < 0.0001) and were more dramatic in R3 than R1 or R2. The action of nicotine on central pathways located at the interneuronal network of the brainstem, basal ganglia, and C fiber structures involved with this reflex seems to be the most likely mechanism for these findings.