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Peter U Tse; fMRI reveals the neuronal substrate underlying form and motion processing in transformational apparent motion. Journal of Vision 2003;3(9):167. doi: https://doi.org/10.1167/3.9.167.
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Transformational apparent motion (TAM) occurs when a figure changes discretely from one configuration to another overlapping configuration. Rather than an abrupt shape change, the initial shape is perceived to transform smoothly into the final shape as if animated by a series of intermediate shapes. Here fMRI has been used to determine the neurophysiological substrate of this motion illusion.
In the past, fMRI has been used both to locate areas of the human brain involved in processing form and to locate areas involved in processing motion. Relatively few studies, however, have examined how the form and motion processing streams interact. For this purpose, Transformational Apparent (Tse, Cavanagh, and Nakayama, 1995, 1998) is an ideal stimulus probe, because the direction of motion that is perceived depends on the form relationships that exist between successive stimuli (Tse and Logothetis, 2002).
In two experiments, TAM stimuli and control stimuli that were similar in low-level properties, but which did not give rise to the perception of TAM, were blocked. The BOLD signal was measured using a 1.5T GE scanner. Voxel volume was 3.75×3.75×5mm in 25 horizontal slices collected using single-shot T2* weighted gradient-recalled EPI sequences
When TAM and non-TAM stimuli were contrasted using the General Linear Model, there was significantly more BOLD signal in the following areas bilaterally: Areas 18 and 19, area MT+, and area 7 in the superior parietal lobule and precuneus. These data are consistent with models that place a stage of texture and form analysis in extrastriate cortex before motion processing in area MT+.
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