SSVEP (steady-state visual evoked potential) is known as EEG response for alternated visual stimulation about 3.5-75Hz that used for signal source of the brain-computer interface. Whereas there are many studies for SSVEP or visual sensory system, little is known that how is central nerves system generate EEG response at high frequency visual stimulation such as SSVEP. To simplify the experimental neural pathway, we focused on the optic tectum of the Goldfish that receives direct visual inputs from the retina. For the Goldfish has been used as experimental animal for oculomotor reflex, thought to be suitable for experimental model for visual system. In this study, single unit activities of the optic tectum were recorded during flashing stimulation at 1Hz or 15Hz to pupil of the Goldfish. Most part of unit group 1 that only showed ON- or OFF-response at 1Hz showed abolished response at 15Hz stimulation. In contrast, most part of unit group 2 that showed ON-OFF response at 1Hz remained ON- or OFF-response at 15Hz stimulation. In addition, unit group 2 showed shorter latency of OFF response than ON response at 1Hz stimulation significantly. These results suggests unit group that showed ON-OFF response at low frequency have a following activity with high frequency stimulation.
