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Activation of the Human MT Complex by Motion in Depth Induced by a Moving Cast Shadow

A moving cast shadow is a powerful monocular depth cue for motion perception in depth. For example, when a cast shadow moves away from or toward an object in a two-dimensional plane, the object appears to move toward or away from the observer in depth, respectively, whereas the size and position of...

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Autores principales: Katsuyama, Narumi, Usui, Nobuo, Taira, Masato
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5012579/
https://www.ncbi.nlm.nih.gov/pubmed/27597999
http://dx.doi.org/10.1371/journal.pone.0162555
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author Katsuyama, Narumi
Usui, Nobuo
Taira, Masato
author_facet Katsuyama, Narumi
Usui, Nobuo
Taira, Masato
author_sort Katsuyama, Narumi
collection PubMed
description A moving cast shadow is a powerful monocular depth cue for motion perception in depth. For example, when a cast shadow moves away from or toward an object in a two-dimensional plane, the object appears to move toward or away from the observer in depth, respectively, whereas the size and position of the object are constant. Although the cortical mechanisms underlying motion perception in depth by cast shadow are unknown, the human MT complex (hMT+) is likely involved in the process, as it is sensitive to motion in depth represented by binocular depth cues. In the present study, we examined this possibility by using a functional magnetic resonance imaging (fMRI) technique. First, we identified the cortical regions sensitive to the motion of a square in depth represented via binocular disparity. Consistent with previous studies, we observed significant activation in the bilateral hMT+, and defined functional regions of interest (ROIs) there. We then investigated the activity of the ROIs during observation of the following stimuli: 1) a central square that appeared to move back and forth via a moving cast shadow (mCS); 2) a segmented and scrambled cast shadow presented beside the square (sCS); and 3) no cast shadow (nCS). Participants perceived motion of the square in depth in the mCS condition only. The activity of the hMT+ was significantly higher in the mCS compared with the sCS and nCS conditions. Moreover, the hMT+ was activated equally in both hemispheres in the mCS condition, despite presentation of the cast shadow in the bottom-right quadrant of the stimulus. Perception of the square moving in depth across visual hemifields may be reflected in the bilateral activation of the hMT+. We concluded that the hMT+ is involved in motion perception in depth induced by moving cast shadow and by binocular disparity.
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spelling pubmed-50125792016-09-27 Activation of the Human MT Complex by Motion in Depth Induced by a Moving Cast Shadow Katsuyama, Narumi Usui, Nobuo Taira, Masato PLoS One Research Article A moving cast shadow is a powerful monocular depth cue for motion perception in depth. For example, when a cast shadow moves away from or toward an object in a two-dimensional plane, the object appears to move toward or away from the observer in depth, respectively, whereas the size and position of the object are constant. Although the cortical mechanisms underlying motion perception in depth by cast shadow are unknown, the human MT complex (hMT+) is likely involved in the process, as it is sensitive to motion in depth represented by binocular depth cues. In the present study, we examined this possibility by using a functional magnetic resonance imaging (fMRI) technique. First, we identified the cortical regions sensitive to the motion of a square in depth represented via binocular disparity. Consistent with previous studies, we observed significant activation in the bilateral hMT+, and defined functional regions of interest (ROIs) there. We then investigated the activity of the ROIs during observation of the following stimuli: 1) a central square that appeared to move back and forth via a moving cast shadow (mCS); 2) a segmented and scrambled cast shadow presented beside the square (sCS); and 3) no cast shadow (nCS). Participants perceived motion of the square in depth in the mCS condition only. The activity of the hMT+ was significantly higher in the mCS compared with the sCS and nCS conditions. Moreover, the hMT+ was activated equally in both hemispheres in the mCS condition, despite presentation of the cast shadow in the bottom-right quadrant of the stimulus. Perception of the square moving in depth across visual hemifields may be reflected in the bilateral activation of the hMT+. We concluded that the hMT+ is involved in motion perception in depth induced by moving cast shadow and by binocular disparity. Public Library of Science 2016-09-06 /pmc/articles/PMC5012579/ /pubmed/27597999 http://dx.doi.org/10.1371/journal.pone.0162555 Text en © 2016 Katsuyama et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Katsuyama, Narumi
Usui, Nobuo
Taira, Masato
Activation of the Human MT Complex by Motion in Depth Induced by a Moving Cast Shadow
title Activation of the Human MT Complex by Motion in Depth Induced by a Moving Cast Shadow
title_full Activation of the Human MT Complex by Motion in Depth Induced by a Moving Cast Shadow
title_fullStr Activation of the Human MT Complex by Motion in Depth Induced by a Moving Cast Shadow
title_full_unstemmed Activation of the Human MT Complex by Motion in Depth Induced by a Moving Cast Shadow
title_short Activation of the Human MT Complex by Motion in Depth Induced by a Moving Cast Shadow
title_sort activation of the human mt complex by motion in depth induced by a moving cast shadow
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5012579/
https://www.ncbi.nlm.nih.gov/pubmed/27597999
http://dx.doi.org/10.1371/journal.pone.0162555
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