Adaptation characteristics of steady-state motion visual evoked potentials.

OBJECTIVE

Motion visual evoked potentials (motion VEPs) are used in clinical diagnosis and basic research. Employing steady-state rather than the usual transient motion VEPs simplifies statistical evaluation and might drastically reduce examination durations. Protocols for recording transient motion-onset VEPs usually involve fairly long recovery intervals between trials to avoid neural adaptation. This is not feasible for steady-state VEPs. We investigated how adaptation affects the steady-state motion VEP.

METHODS

Oscillatory (13.3rev/s) and continuous uni-directional random-dot motion served as adaptation stimuli. Steady-state motion VEPs and, for comparison, transient motion VEPs were recorded.

RESULTS

In the first experiment, we investigated how adaptation affects the recordings. Contrary to our expectation, we did not find any sizable effect. However, there was a large inter-individual variability in steady-state amplitude and no correlation across subjects between transient and steady-state amplitude. In the second experiment, we confirmed that the steady-state VEP reflects veridical motion processing by assessing its susceptibility to uni-directional pre-adaptation.

CONCLUSIONS

Taken together, the results suggest that steady-state motion VEPs provide a fast method of recording motion responses without suffering from adaptation, but at the expense of inter-individual reproducibility.