[Habituation of the human orbicularis oculi reflex]

The habituation of the electrically (stimulation of the supraorbital nerve) elicited orbicularis oculi reflex (OOR) was investigated in 51 healthy volunteers (average age: 39 years). Ten reflex responses were registered from the left and right side including eyes open, eyes closed, and during task performance. The stimulus frequency was 1/s. The data were transmitted to an LAB 8e computer and statistically treated. The influence of stimulus frequency on habituation was examined separately. The following parameters of habituation as devised by Thompson and Spencer were demonstrable: dishabituation, habituation of dishabituation, spontaneous recovery, and influence of stimulus intensity. The analysis of habituation during task performance with the Kruskal-Wallis test revealed a statistically significant decrease of habituation. The early reflex component (R1) amplitudes increased during the 1/s stimulation. This effect was also statistically significant. The increase in R1 amplitude during 1/s stimulation was interpreted as "facilitation".