Neural Activity Correlated with Intra- or Cross-modal Cued Illusory Line Motion: An fMRI Study

When a cue is presented and followed by a line, we perceive that the line elongates from the cued side (Illusory Line Motion; ILM). This visual motion illusion effect is produced by both captured (stimulus-induced) and voluntary attention, and by both intra- and cross-modal cues, suggesting that a modality non-specific neural mechanism is concerned. To investigate neural correlates of this illusion, we studied this issue by employing fMRI and psychophysical experiments. The results showed that neural activities corresponding to this illusion well-agreed with those of spatial attention, suggesting that this illusion is based on stimulus-modality non-specific visuo-spatial attention. In addition, hMT+activation was correlated with conscious perception, indicating that subjective perception of visual motion is founded on this area's activation.