Limits...
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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Comparison of activation patterns in conjunction and individual contrasts of the SfT experiment on flattened hemispheres. SPM plotting the voxels significant at the P < 0.001 unc level (random effects) in the conjunction (A), the contrast 3D constrained minus 2D constrained-scrambled (B), 3D lattice minus 2D lattice scrambled (C), 3D lattice minus 2D lattice-aligned (D), and 3D lattice minus 2D uniform texture (E). In (B–E) the red outlines reproduce the activation in the conjunction (A).
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fig9: Comparison of activation patterns in conjunction and individual contrasts of the SfT experiment on flattened hemispheres. SPM plotting the voxels significant at the P < 0.001 unc level (random effects) in the conjunction (A), the contrast 3D constrained minus 2D constrained-scrambled (B), 3D lattice minus 2D lattice scrambled (C), 3D lattice minus 2D lattice-aligned (D), and 3D lattice minus 2D uniform texture (E). In (B–E) the red outlines reproduce the activation in the conjunction (A).

Mentions: To understand the importance of the conjunction analysis involving several contrasts compared with a single contrast with the most critical 2D condition, the activation patterns of the conjunction and its 4 constitutive contrasts are plotted on flatmaps in Figure 9. Somewhat counter intuitively the activation patterns for the 2 contrasts using the most crucial control conditions, the scrambled conditions, are fairly extensive (Fig. 9B,C). In particular contrasting the 3D lattice to the 2D scrambled lattice condition yields activation in fusiform regions which are not removed by the 2D lattice-aligned control (Fig. 9D), but are eliminated by the uniform-texture condition (Fig. 9E). This suggests that these regions are driven by patches of uniform texture, which are present in the 3D conditions (Fig. 1C). Indeed an earlier study showed that judgments about 2D texture involve these ventral regions (Peuskens et al. 2004). Notice also that this figure indicates that the activation pattern in the conjunction corresponds indeed to what one expects.


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

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

Comparison of activation patterns in conjunction and individual contrasts of the SfT experiment on flattened hemispheres. SPM plotting the voxels significant at the P < 0.001 unc level (random effects) in the conjunction (A), the contrast 3D constrained minus 2D constrained-scrambled (B), 3D lattice minus 2D lattice scrambled (C), 3D lattice minus 2D lattice-aligned (D), and 3D lattice minus 2D uniform texture (E). In (B–E) the red outlines reproduce the activation in the conjunction (A).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig9: Comparison of activation patterns in conjunction and individual contrasts of the SfT experiment on flattened hemispheres. SPM plotting the voxels significant at the P < 0.001 unc level (random effects) in the conjunction (A), the contrast 3D constrained minus 2D constrained-scrambled (B), 3D lattice minus 2D lattice scrambled (C), 3D lattice minus 2D lattice-aligned (D), and 3D lattice minus 2D uniform texture (E). In (B–E) the red outlines reproduce the activation in the conjunction (A).
Mentions: To understand the importance of the conjunction analysis involving several contrasts compared with a single contrast with the most critical 2D condition, the activation patterns of the conjunction and its 4 constitutive contrasts are plotted on flatmaps in Figure 9. Somewhat counter intuitively the activation patterns for the 2 contrasts using the most crucial control conditions, the scrambled conditions, are fairly extensive (Fig. 9B,C). In particular contrasting the 3D lattice to the 2D scrambled lattice condition yields activation in fusiform regions which are not removed by the 2D lattice-aligned control (Fig. 9D), but are eliminated by the uniform-texture condition (Fig. 9E). This suggests that these regions are driven by patches of uniform texture, which are present in the 3D conditions (Fig. 1C). Indeed an earlier study showed that judgments about 2D texture involve these ventral regions (Peuskens et al. 2004). Notice also that this figure indicates that the activation pattern in the conjunction corresponds indeed to what one expects.

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