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The extraction of 3D shape from texture and shading in the human brain.

Georgieva SS, Todd JT, Peeters R, Orban GA - Cereb. Cortex (2008)

Bottom Line: The results of both passive and active experiments reveal that the extraction of 3D SfT involves the bilateral caudal inferior temporal gyrus (caudal ITG), lateral occipital sulcus (LOS) and several bilateral sites along the intraparietal sulcus.Additional results from psychophysical experiments reveal that this difference in neuronal substrate cannot be explained by a difference in strength between the 2 cues.These results underscore the importance of the posterior part of the lateral occipital complex for the extraction of visual 3D shape information from all depth cues, and they suggest strongly that the importance of shading is diminished relative to other cues for the analysis of 3D shape in parietal regions.

View Article: PubMed Central - PubMed

Affiliation: Laboratorium voor Neuro- en Psychofysiologie, Katholieke Universiteit Leuven School of Medicine, Campus Gasthuisberg, B-3000 Leuven, Belgium.

ABSTRACT
We used functional magnetic resonance imaging to investigate the human cortical areas involved in processing 3-dimensional (3D) shape from texture (SfT) and shading. The stimuli included monocular images of randomly shaped 3D surfaces and a wide variety of 2-dimensional (2D) controls. The results of both passive and active experiments reveal that the extraction of 3D SfT involves the bilateral caudal inferior temporal gyrus (caudal ITG), lateral occipital sulcus (LOS) and several bilateral sites along the intraparietal sulcus. These areas are largely consistent with those involved in the processing of 3D shape from motion and stereo. The experiments also demonstrate, however, that the analysis of 3D shape from shading is primarily restricted to the caudal ITG areas. Additional results from psychophysical experiments reveal that this difference in neuronal substrate cannot be explained by a difference in strength between the 2 cues. These results underscore the importance of the posterior part of the lateral occipital complex for the extraction of visual 3D shape information from all depth cues, and they suggest strongly that the importance of shading is diminished relative to other cues for the analysis of 3D shape in parietal regions.

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Activity profiles plotting averaged MR signal changes compared with fixation condition over all subjects (n = 18). (A) 3D SfT sensitive regions: L and R caudal ITG, L and R LOS, L VIPSt, R VIPS, R POIPSt, L and R DIPSM, and R DIPSAs. (B) 3D SfS sensitive regions: L and R caudal ITG. The error bars indicate SEs between subjects. Color bars indicate different conditions following the same convention as in Figure 1.
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fig8: Activity profiles plotting averaged MR signal changes compared with fixation condition over all subjects (n = 18). (A) 3D SfT sensitive regions: L and R caudal ITG, L and R LOS, L VIPSt, R VIPS, R POIPSt, L and R DIPSM, and R DIPSAs. (B) 3D SfS sensitive regions: L and R caudal ITG. The error bars indicate SEs between subjects. Color bars indicate different conditions following the same convention as in Figure 1.

Mentions: Figure 8A plots the activity profiles of the 3D SfT activation sites, obtained by averaging, across all 18 subjects, the profiles of the group local maximum. In general, MR activity is 30–50% greater in the 3D conditions than in the 2D control conditions. The significance of the individual contrast is listed in Table 1. As could be expected from a conjunction analysis, these contrasts all reach P < 0.001 uncorrected in all regions significant in the conjunction.


The extraction of 3D shape from texture and shading in the human brain.

Georgieva SS, Todd JT, Peeters R, Orban GA - Cereb. Cortex (2008)

Activity profiles plotting averaged MR signal changes compared with fixation condition over all subjects (n = 18). (A) 3D SfT sensitive regions: L and R caudal ITG, L and R LOS, L VIPSt, R VIPS, R POIPSt, L and R DIPSM, and R DIPSAs. (B) 3D SfS sensitive regions: L and R caudal ITG. The error bars indicate SEs between subjects. Color bars indicate different conditions following the same convention as in Figure 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2536698&req=5

fig8: Activity profiles plotting averaged MR signal changes compared with fixation condition over all subjects (n = 18). (A) 3D SfT sensitive regions: L and R caudal ITG, L and R LOS, L VIPSt, R VIPS, R POIPSt, L and R DIPSM, and R DIPSAs. (B) 3D SfS sensitive regions: L and R caudal ITG. The error bars indicate SEs between subjects. Color bars indicate different conditions following the same convention as in Figure 1.
Mentions: Figure 8A plots the activity profiles of the 3D SfT activation sites, obtained by averaging, across all 18 subjects, the profiles of the group local maximum. In general, MR activity is 30–50% greater in the 3D conditions than in the 2D control conditions. The significance of the individual contrast is listed in Table 1. As could be expected from a conjunction analysis, these contrasts all reach P < 0.001 uncorrected in all regions significant in the conjunction.

Bottom Line: The results of both passive and active experiments reveal that the extraction of 3D SfT involves the bilateral caudal inferior temporal gyrus (caudal ITG), lateral occipital sulcus (LOS) and several bilateral sites along the intraparietal sulcus.Additional results from psychophysical experiments reveal that this difference in neuronal substrate cannot be explained by a difference in strength between the 2 cues.These results underscore the importance of the posterior part of the lateral occipital complex for the extraction of visual 3D shape information from all depth cues, and they suggest strongly that the importance of shading is diminished relative to other cues for the analysis of 3D shape in parietal regions.

View Article: PubMed Central - PubMed

Affiliation: Laboratorium voor Neuro- en Psychofysiologie, Katholieke Universiteit Leuven School of Medicine, Campus Gasthuisberg, B-3000 Leuven, Belgium.

ABSTRACT
We used functional magnetic resonance imaging to investigate the human cortical areas involved in processing 3-dimensional (3D) shape from texture (SfT) and shading. The stimuli included monocular images of randomly shaped 3D surfaces and a wide variety of 2-dimensional (2D) controls. The results of both passive and active experiments reveal that the extraction of 3D SfT involves the bilateral caudal inferior temporal gyrus (caudal ITG), lateral occipital sulcus (LOS) and several bilateral sites along the intraparietal sulcus. These areas are largely consistent with those involved in the processing of 3D shape from motion and stereo. The experiments also demonstrate, however, that the analysis of 3D shape from shading is primarily restricted to the caudal ITG areas. Additional results from psychophysical experiments reveal that this difference in neuronal substrate cannot be explained by a difference in strength between the 2 cues. These results underscore the importance of the posterior part of the lateral occipital complex for the extraction of visual 3D shape information from all depth cues, and they suggest strongly that the importance of shading is diminished relative to other cues for the analysis of 3D shape in parietal regions.

Show MeSH