Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6030839 | NeuroImage | 2012 | 10 Pages |
Abstract
The “Rotating Snakes” figure elicits a clear sense of anomalous motion in stationary repetitive patterns. We used an event-related fMRI adaptation paradigm to investigate cortical mechanisms underlying the illusory motion. Following an adapting stimulus (S1) and a blank period, a probe stimulus (S2) that elicited illusory motion either in the same or in the opposite direction was presented. Attention was controlled by a fixation task, and control experiments precluded explanations in terms of artefacts of local adaptation, afterimages, or involuntary eye movements. Recorded BOLD responses were smaller for S2 in the same direction than S2 in the opposite direction in V1-V4, V3A, and MT+, indicating direction-selective adaptation. Adaptation in MTÂ + was correlated with adaptation in V1 but not in V4. With possible downstream inheritance of adaptation, it is most likely that adaptation predominantly occurred in V1. The results extend our previous findings of activation in MTÂ + (I. Kuriki, H. Ashida, I. Murakami, and A. Kitaoka, 2008), revealing the activity of the cortical network for motion processing from V1 towards MT+. This provides evidence for the role of front-end motion detectors, which has been assumed in proposed models of the illusion.
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Authors
Hiroshi Ashida, Ichiro Kuriki, Ikuya Murakami, Rumi Hisakata, Akiyoshi Kitaoka,