Maurer JP & Bach M (2003) Isolating motion responses in visual evoked potentials by pre-adapting flicker-sensitive mechanisms. Experimental Brain Research 151:536–541
Onset of visual motion evokes a component in the EEG, the motion onset VEP. Exploring its motion specificity with a direction-specific adaptation paradigm, previous work demonstrated that less than 50% of the motion onset VEP represents actual motion detection. We here tested whether pre-adaptation of flicker-sensitive mechanisms can help to isolate motion-specific responses in the VEP. Flicker pre-adaptation was accomplished by limiting dot lifetime in the random-dot kinematograms that we used to study the direction specificity of motion adaptation. With unlimited dot lifetime, motion adaptation reduced the VEP amplitude to 35% (adapted direction) resp. 50% (opposite direction). With the shortest dot lifetime (40 ms), motion adaptation reduced the amplitude to 55% (adapted direction) resp. 70% (opposite direction). These findings suggest that random-dot kinematograms with short dot lifetimes could improve the investigation of human motion processing, be it in electrophysiology or other fields: While pre-adapting flicker-related components, such stimuli still evoke a sizable response, of which an estimated 70% is motion-specific.