title: The neural basis of the Enigma illusion: a transcranial magnetic stimulation study.
abstract: The aim of this study was to test the role of the visual primary (V1) and the middle temporal area (V5/MT) in the illusory motion perception evoked by the Enigma figure. The Enigma figure induces a visual illusion that is characterized by apparent rotatory motion in the presence of a static figure. By means of repetitive transcranial magnetic stimulation (rTMS) we show that V5/MT is causally linked to the illusory perception of motion. When rTMS was applied bilaterally over V5/MT just prior to presentation of the Enigma figure, the perception of illusory motion was disrupted for approximately 400 ms resulting in a delayed illusion onset. In contrast, rTMS applied over V1 did not have any effect on the illusory perception of motion. These results show that V5/MT, a visual cortical area associated with real motion perception, is also important for the perception of illusory motion, while V1 appears not to be functionally involved in illusory motion perception.
authors.affiliation: Department of Neurological, Neuropsychological, Morphological and Motor Sciences, University of Verona, Verona, Italy. manuela.ruzzoli@cognitiveneuroscience.it
authors.forename: Manuela
authors.initials: M
authors.lastname: Ruzzoli
authors.forename: Simone
authors.initials: S
authors.lastname: Gori
authors.forename: Andrea
authors.initials: A
authors.lastname: Pavan
authors.forename: Cornelia
authors.initials: C
authors.lastname: Pirulli
authors.forename: Carlo A
authors.initials: CA
authors.lastname: Marzi
authors.forename: Carlo
authors.initials: C
authors.lastname: Miniussi
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007088:Illusions / Q000502:physiology*; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time; D050781:Transcranial Magnetic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult