Two-Dimensional Mapping of the Central and Parafoveal Visual Field to Human Visual Cortex

Schira, Mark M.; Wade, Alex R.; Tyler, Christopher W.

doi:10.1152/jn.00972.2006

Cited by 120 publications

(166 citation statements)

References 60 publications

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“…The retinotopic visual areas, V1, V2, etc. were already established in previous studies for each of the observers Schira et al, 2007). The present study focused only on area V1.…”

Section: The Structure Of the Response For Different Stimulus Regionsmentioning

confidence: 92%

Independent components in stimulus-related BOLD signals and estimation of the underlying neural responses

2008

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This is the published version of the paper.This version of the publication may differ from the final published version. Permanent repository link A R T I C L E I N F O A B S T R A C TArticle history: IntroductionFunctional magnetic-resonance imaging (fMRI) based on the blood oxygenation-level dependent (BOLD) signal is a powerful technique for studying the neural response in the cortex. Most previous work has been based on the assumption that the BOLD signal is a unitary response to a single form of stimulus S(t), usually in the form of a linear convolution of a hemodynamic response function (HRF) with the temporal waveform of the stimulus time sequence (Bandettini et al., 1993;Friston et al., 1994;Boynton et al., 1996). In most cases, it is assumed that the HRF incorporates both the cortical response to the stimulus and the hemodynamic response of the blood to the oxygen requirements of the cortical response. However, the situation may be much more complicated, with multiple components of neural response to the stimulus weighted differentially across the cortex (Zacks et al., 2001;d'Avossa et al., 2003;Bellgowan et al., 2003;Calhoun et al., 2004a;Fox et al., 2005), such that any one voxel contains contributions from more than one neural time course. If these time course variations are small relative to the BOLD temporal resolution, they may be negligible for an overall analysis of response strength, but the cited studies show non-negligible variations that require a more detailed analysis. For this reason, consistent with Friston et al. (1998Friston et al. ( , 2000, Buxton et al. (2004) and others, we restrict the term HRF to the dynamics of the blood response to the metabolic demands of the neural processing and consider the neural response to the stimulus as a separate process. This leads to the model of the BOLD mechanisms shown in Fig. 1.

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“…The retinotopic visual areas, V1, V2, etc. were already established in previous studies for each of the observers Schira et al, 2007). The present study focused only on area V1.…”

Section: The Structure Of the Response For Different Stimulus Regionsmentioning

confidence: 92%

Independent components in stimulus-related BOLD signals and estimation of the underlying neural responses

2008

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“…The stimuli covered only the central 3°r adius of the visual field. For many years, labs using conventional methods stopped visual field mapping at 0.5°-2°eccentricity, believing that central foveal maps could not be accurately measured (Dougherty et al, 2003;Liu et al, 2005;Schira et al, 2007;Silver et al, 2007;Somers et al, 1999;Tootell and Hadjikhani, 2001). Notice that with the pRF model-based method, we trace with high precision the visual field maps to the center of the foveal representation.…”

Section: V1 and Lo Respond Differently To Identical Traveling Wave Stmentioning

confidence: 95%

Population receptive field estimates in human visual cortex

2008

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We introduce functional MRI methods for estimating the neuronal population receptive field (pRF). These methods build on conventional visual field mapping that measures responses to ring and wedge patterns shown at a series of visual field locations and estimates the single position in the visual field that produces the largest response. The new method computes a model of the population receptive field from responses to a wide range of stimuli and estimates the visual field map as well as other neuronal population properties, such as receptive field size and laterality. The visual field maps obtained with the pRF method are more accurate than those obtained using conventional visual field mapping, and we trace with high precision the visual field maps to the center of the foveal representation. We report quantitative estimates of pRF size in medial, lateral and ventral occipital regions of human visual cortex. Also, we quantify the amount of input from ipsi-and contralateral visual fields. The human pRF size estimates in V1-V3 agree well with electrophysiological receptive field measurements at a range of eccentricities in corresponding locations within monkey and human visual field maps. The pRF method is non-invasive and can be applied to a wide range of conditions when it is useful to link fMRI signals in the visual pathways to neuronal receptive fields.

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“…Retinotopic areas V3A, V3B and V7 were speciWed in accordance with Press et al (2001) and Tyler et al (2005). Locations of the projections of the stimulus borders in retinotopic regions used the procedures described in Tyler et al (2005) and Schira et al (2007). BrieXy, traveling wave stimuli-standard cyclic ring and wedge scans were used to deWne the eccentricity and meridian phase maps, respectively, throughout the occipital lobes.…”

Section: Data Analysis and Visualizationmentioning

confidence: 99%

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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Two-Dimensional Mapping of the Central and Parafoveal Visual Field to Human Visual Cortex

Cited by 120 publications

References 60 publications

Independent components in stimulus-related BOLD signals and estimation of the underlying neural responses

Independent components in stimulus-related BOLD signals and estimation of the underlying neural responses

Population receptive field estimates in human visual cortex

Occipital network for figure/ground organization

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