title: An intracranial event-related potential study on transformational apparent motion. Does its neural processing differ from real motion?
abstract: How the brain processes visual stimuli has been extensively studied using scalp surface electrodes and magnetic resonance imaging. Using these and other methods, complex gratings have been shown to activate the ventral visual stream, whereas moving stimuli preferentially activate the dorsal stream. In the current study, a first experiment assessed brain activations evoked by complex gratings using intracranial electroencephalography in 10 epileptic patients implanted with subdural electrodes. These stimuli of intermediate levels of complexity were presented in such a way that transformational apparent motion (TAM) was perceived. Responses from both the ventral and the dorsal pathways were obtained. The response characteristics of visual area 4 and the fusiform cortex were of similar amplitudes, suggesting that both ventral areas are recruited for the processing of complex gratings. On the other hand, TAM-induced responses of dorsal pathway areas were relatively noisier and of lower amplitudes, suggesting that TAM does not activate motion-specific structures to the same extent as does real motion. To test this hypothesis, we examined the activity evoked by TAM in comparison to the one produced by real motion in a patient implanted with the same subdural electrodes. Findings demonstrated that neural response to real motion was much stronger than that evoked by TAM, in both the primary visual cortex (V1) and other motion-sensitive areas within the dorsal pathway. These results support the conclusion that apparent motion, even if perceptually similar to real motion, is not processed in a similar manner.
authors.affiliation: Department of Psychology, Centre de Recherche en Neuropsychologie et Cognition, Université de Montréal, C.P. 6128 Succ Centre-ville, Montréal, QC H3C 3J7, Canada.
authors.forename: Josie-Anne
authors.initials: JA
authors.lastname: Bertrand
authors.forename: Maryse
authors.initials: M
authors.lastname: Lassonde
authors.forename: Manon
authors.initials: M
authors.lastname: Robert
authors.forename: Dang Khoa
authors.initials: DK
authors.lastname: Nguyen
authors.forename: Armando
authors.initials: A
authors.lastname: Bertone
authors.forename: Marie-Ève
authors.initials: MÈ
authors.lastname: Doucet
authors.forename: Alain
authors.initials: A
authors.lastname: Bouthillier
authors.forename: Franco
authors.initials: F
authors.lastname: Lepore
mesh_terms: D001931:Brain Mapping; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D005071:Evoked Potentials / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009038:Motion; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time; D014793:Visual Cortex / Q000503:physiopathology*; D014795:Visual Pathways; D055815:Young Adult
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