The specificity of cortical region KO to depth structure

Tyler, Christopher W.; Likova, Lora T.; Kontsevich, Leonid L.; Wade, Alex R.

doi:10.1016/j.neuroimage.2005.09.067

Cited by 68 publications

(75 citation statements)

References 54 publications

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“…In contrast, previous studies implicated areas V3A (Backus et al 2001;Gulyas and Roland 1994;Mendola et al 1999;Tsao et al 2003) and V3B/KO (Brouwer et al 2005;Tyler et al 2006;Van Oostende et al 1997;Zeki et al 2003) in the analysis of disparity-defined surfaces and boundaries. Further, caudal intaparietal (CIP) regions were previously implicated in processing 3D object orientation and surface slant (James et al 2002;Naganuma et al 2005;Sakata et al 2005;Taira et al 2000) rather than being involved in form discrimination (Shikata et al 2001).…”

Section: Disparity Processing and 3d Shape Perceptionmentioning

confidence: 85%

“…We examined the average fMRI response evoked by stimuli with different levels of disparity-defined shape coherence in early visual areas (V1, V2, V3, V3A, V3B/KO, VP/V3, V4), higher ventral areas (LOC: LO, pFs), and dorsal visual areas (hMTϩ/V5: MT, MST) previously implicated in the processing of disparity information in the human brain (i.e., disparitydefined planes: Backus et al 2001;Gulyas and Roland 1994;Neri et al 2004;Rutschmann and Greenlee 2004;Tyler et al 2006;shape contours: Gilaie-Dotan et al 2002;Kourtzi et al 2002Kourtzi et al , 2003Mendola et al 1999;or gradients: (Brouwer et al 2005;Welchman et al 2005). Figure 3, B-D shows the effect of increasing disparitydefined shape coherence on the fMRI response across cortical areas (V1, V2, ventral, dorsal areas).…”

Section: Fmri Responsesmentioning

confidence: 99%

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Neural Correlates of Disparity-Defined Shape Discrimination in the Human Brain

Chandrasekaran

Canon

Dahmen³

et al. 2007

Journal of Neurophysiology

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Chandrasekaran C, Canon V, Dahmen JC, Kourtzi Z, Welchman AE. Neural correlates of disparity-defined shape discrimination in the human brain. J Neurophysiol 97: [1553][1554][1555][1556][1557][1558][1559][1560][1561][1562][1563][1564][1565] 2007. First published December 6, 2006; doi:10.1152/jn.01074.2006. Binocular disparity, the slight differences between the images registered by our two eyes, provides an important cue when estimating the three-dimensional (3D) structure of the complex environment we inhabit. Sensitivity to binocular disparity is evident at multiple levels of the visual hierarchy in the primate brain, from early visual cortex to parietal and temporal areas. However, the relationship between activity in these areas and key perceptual functions that exploit disparity information for 3D shape perception remains an important open question. Here we investigate the link between human cortical activity and the perception of disparity-defined shape, measuring fMRI responses concurrently with psychophysical shape judgments. We parametrically degraded the coherence of shapes by shuffling the spatial position of dots whose disparity defined the 3D structure and investigated the effect of this stimulus manipulation on both cortical activity and shape discrimination. We report significant relationships between shape coherence and fMRI response in both dorsal (V3, hMTϩ/V5) and ventral (LOC) visual areas that correspond to the observers' discrimination performance. In contrast to previous suggestions of a dichotomy of disparity-related processes in the ventral and dorsal streams, these findings are consistent with proposed interactions between these pathways that may mediate a continuum of processes important in perceiving 3D shape from coarse contour segmentation to fine curvature estimation. I N T R O D U C T I O NEveryday human behavior depends on the brain estimating the depth structure of the nearby environment so that we can avoid dangers and exploit opportunities. A powerful source of information to depth structure is provided by the slight differences between the retinal images registered by our two eyes (binocular disparity). The brain's use of binocular disparity has been studied extensively Howard and Rogers 2002), largely because of the quantitative relation between disparity and the depth structure of the environment (Longuet-Higgins 1982), the exquisite sensitivity of the brain to disparity (Westheimer and McKee 1978), and the observation that horizontal binocular disparity provides a powerful impression of depth even under impoverished viewing conditions (Julesz 1971).Neurophysiological and imaging studies revealed selectivity for binocular disparity at multiple levels of the visual hierarchy in the monkey and the human brain from early visual areas, to object-and motion-selective areas and the parietal cortex (for reviews see Cumming and DeAngelis 2001;Neri 2005; Orban et al. 2006a,b;Parker 2004). However, understanding how activity in these multiple disparity-selectivity regions relates to k...

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Section: Disparity Processing and 3d Shape Perceptionmentioning

confidence: 85%

Section: Fmri Responsesmentioning

confidence: 99%

Neural Correlates of Disparity-Defined Shape Discrimination in the Human Brain

Chandrasekaran

Canon

Dahmen³

et al. 2007

Journal of Neurophysiology

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“…In the fMRI paradigm, the main occipital responses to DVN are found in V1, while V3A and especially hMT/V5+ respond less to DVN than to coherent motion (Tyler et al 2006).…”

Section: Stimulimentioning

confidence: 90%

Occipital network for figure/ground organization

Likova

Tyler

2008

Exp Brain Res

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This is the accepted version of the paper.This version of the publication may differ from the final published version. Abstract To study the cortical mechanism of Wgure/ ground categorization in the human brain, we employed fMRI and the temporal-asynchrony paradigm. This paradigm is able to eliminate any diVerential activation for local stimulus features, and thus to identify only global perceptual interactions. Strong segmentation of the image into diVerent spatial conWgurations was generated solely from temporal asynchronies between zones of homogeneous dynamic noise. The Wgure/ground conWguration was a single geometric Wgure enclosed in a larger surround region. In a control condition, the Wgure/ground organization was eliminated by segmenting the noise Weld into many identical temporal-asynchrony stripes. The manipulation of the type of perceptual organization triggered dramatic reorganization in the cortical activation pattern. The Wgure/ground conWguration generated suppression of the ground representation (limited to early retinotopic visual cortex, V1 and V2) and strong activation in the motion complex hMT+/ V5+; conversely, both responses were abolished when the Wgure/ground organization was eliminated. These results suggest that Wgure/ground processing is mediated by topdown suppression of the ground representation in the earliest visual areas V1/V2 through a signal arising in the motion complex. We propose a model of a recurrent cortical architecture incorporating suppressive feedback that operates in a topographic manner, forming a Wgure/ground categorization network distinct from that for "pure" scene segmentation and thus underlying the perceptual organization of dynamic scenes into cognitively relevant components. Permanent repository link

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“…We use advanced fMRI analysis methods (multivoxel pattern analysis, MVPA) that allow us to evaluate whether small biases across voxels related to the preference of the underlying neural populations are statistically reliable (12)(13)(14). Using these methods, we test for fMRI sensitivity in discriminating Light and Shape across various visual, temporal, and parietal regions known to be engaged in the representation of shape from different depth cues (15)(16)(17)(18)(19). We then compare fMRI sensitivity for Light and Shape discrimination to that predicted from the behavioral data (20).…”

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confidence: 99%

Prior knowledge of illumination for 3D perception in the human brain

Gerardin

Kourtzi

Mamassian

2010

Proc. Natl. Acad. Sci. U.S.A.

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In perceiving 3D shape from ambiguous shading patterns, humans use the prior knowledge that the light is located above their head and slightly to the left. Although this observation has fascinated scientists and artists for a long time, the neural basis of this "light from above left" preference for the interpretation of 3D shape remains largely unexplored. Combining behavioral and functional MRI measurements coupled with multivoxel pattern analysis, we show that activations in early visual areas predict best the light source direction irrespective of the perceived shape, but activations in higher occipitotemporal and parietal areas predict better the perceived 3D shape irrespective of the light direction. These findings demonstrate that illumination is processed earlier than the representation of 3D shape in the visual system. In contrast to previous suggestions, we propose that prior knowledge about illumination is processed in a bottom-up manner and influences the interpretation of 3D structure at higher stages of processing.functional MRI | multi-voxel pattern analysis | shape-from-shading | visual cortex | bottom-up processing A lthough the perception of 3D shape is critically important for actions and interactions in the environments we inhabit, most depth cues are ambiguous. As a result, the brain requires additional information based on previous experience with the environment to infer 3D shape from depth cues. In particular, the inference of 3D shape from shading patterns (i.e., using image luminance intensity variations to derive the shape of a surface) relies on the assumption that the scene illuminant is above our heads and slightly to the left (1, 2). Understanding the illumination of a visual scene has fascinated artists and scientists for a long time (3, 4), but the neural basis of this "light from above left" preference for the interpretation of 3D shape remains largely unexplored. Although the light-from-above preference is consistent with an ecological explanation, the left bias remains entirely unexplained. More generally, the light-from-above preference provides a simple example of the way the brain represents prior knowledge and opens the door for the investigation of other types of prior knowledge related to our perception of the motion, shape, and color of objects.Previous neurophysiological and imaging studies have implicated several brain regions in the processing of shape-fromshading: primary visual cortex (V1) (5-9), areas in the caudal inferior temporal gyrus (10) and the inferior parietal sulcus (11). However, the functions mediated by these different cortical areas may differ. In particular, interpreting shape-from-shading may involve at least two different stages of processing. At the first stage, the contrast polarity of edges in the image (dark or bright) is analyzed and related to the light direction so that left and right light directions can be discriminated. At the second stage, contrast edges are grouped together to form 3D shapes so that convex and concave shapes can be dis...

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The specificity of cortical region KO to depth structure

Cited by 68 publications

References 54 publications

Neural Correlates of Disparity-Defined Shape Discrimination in the Human Brain

Neural Correlates of Disparity-Defined Shape Discrimination in the Human Brain

Occipital network for figure/ground organization

Prior knowledge of illumination for 3D perception in the human brain

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