scholarly journals Rapid invariant encoding of scene layout in human OPA

2019 ◽  
Author(s):  
Linda Henriksson ◽  
Marieke Mur ◽  
Nikolaus Kriegeskorte
Keyword(s):  
Human Subjects ◽  
Local Environment ◽  
Visual Navigation ◽  
Image Features ◽  
Response Patterns ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Fmri Response ◽  
Environmental Geometry ◽  
Parahippocampal Place Area

SUMMARYSuccessful visual navigation requires a sense of the geometry of the local environment. How do our brains extract this information from retinal images? Here we visually presented scenes with all possible combinations of five scene-bounding elements (left, right and back wall, ceiling, floor) to human subjects during functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). The fMRI response patterns in the scene-responsive occipital place area (OPA) reflected scene layout with invariance to changes in surface texture. This result contrasted sharply with the primary visual cortex (V1), which reflected low-level image features of the stimuli, and parahippocampal place area (PPA), which showed better texture than layout decoding. MEG indicated that the texture-invariant scene-layout representation is computed from visual input within ~100 ms, suggesting a rapid computational mechanism. Taken together, these results suggest that the cortical representation underlying our instant sense of the environmental geometry is located in OPA.

A functional magnetic resonance imaging study of mental subtraction in human subjects

1999 ◽  
Vol 273 (3) ◽  
pp. 195-199 ◽  
Author(s):  
Pierre Burbaud ◽  
Olivier Camus ◽  
D. Guehl ◽  
Bernard Bioulac ◽  
Jean-Marie Caillé ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Human Subjects ◽  
Imaging Study ◽  
Magnetic Resonance Imaging Study ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging

Radial Biases in the Processing of Motion and Motion-Defined Contours by Human Visual Cortex

2009 ◽  
Vol 102 (5) ◽  
pp. 2974-2981 ◽  
Author(s):  
Colin W. G. Clifford ◽  
Damien J. Mannion ◽  
J. Scott McDonald
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Human Subjects ◽  
Temporal Integration ◽  
Blood Oxygen Level Dependent ◽  
Orientation Tuning ◽  
Bold Signal ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Blood Oxygen Level

Luminance gratings reportedly produce a stronger functional magnetic resonance imaging (fMRI) blood oxygen level–dependent (BOLD) signal in those parts of the retinotopic cortical maps where they are oriented radially to the point of fixation. We sought to extend this finding by examining anisotropies in the response of cortical areas V1–V3 to motion-defined contour stimuli. fMRI at 3 Tesla was used to measure the BOLD signal in the visual cortex of six human subjects. Stimuli were composed of strips of spatial white noise texture presented in an annular window. The texture in alternate strips moved in opposite directions (left–right or up–down). The strips themselves were static and tilted 45° left or right from vertical. Comparison with maps of the visual field obtained from phase-encoded retinotopic analysis revealed systematic patterns of radial bias. For motion, a stronger response to horizontal was evident within V1 and along the borders between V2 and V3. For orientation, the response to leftward tilted contours was greater in left dorsal and right ventral V1–V3. Radial bias for the orientation of motion-defined contours analogous to that reported previously for luminance gratings could reflect cue-invariant processing or the operation of distinct mechanisms subject to similar anisotropies in orientation tuning. Radial bias for motion might be related to the phenomenon of “motion streaks,” whereby temporal integration by the visual system introduces oriented blur along the axis of motion. We speculate that the observed forms of radial bias reflect a common underlying anisotropy in the representation of spatiotemporal image structure across the visual field.

Ocular Dominance in Human V1 Demonstrated by Functional Magnetic Resonance Imaging

1997 ◽  
Vol 77 (5) ◽  
pp. 2780-2787 ◽  
Author(s):  
Ravi S. Menon ◽  
Seiji Ogawa ◽  
John P. Strupp ◽  
Kâmil Uǧurbil
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Ocular Dominance ◽  
Blood Oxygen Level Dependent ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Contrast Mechanism ◽  
Fmri Response ◽  
The Difference

Menon, Ravi S., Seiji Ogawa, John P. Strupp, and Kâmil Uǧurbil. Ocular dominance in human V1 demonstrated by functional magnetic resonance imaging. J. Neurophysiol. 77: 2780–2787, 1997. Very high resolution functional magnetic resonance imaging (fMRI) at a 4 Tesla (T) magnetic field was used to map ocular dominance regions in the human visual cortical layers using the blood oxygen level dependent (BOLD) contrast mechanism. The fMRI response from primary visual cortex (V1) exhibited a distribution of ocular dominance reminiscent of the single-cell recordings of Hubel and Wiesel. Pixels could be grouped into seven categories varying from left-only response to binocular-only response to right-only responses. Nonspecific responses were found in the MRI-visible draining veins as well as in the parenchyma. Although large vessel BOLD signals are easily detectable, regardless of field strength, they demonstrate a fMRI response to photic input that could not be used to distinguish ocular dominance. The difference in BOLD response between a region activated by one eye and that activated by the other is only 2.9% on average. This necessitates the use of a difference paradigm to visualize the regions of ocular dominance accurately. The data show that BOLD-based fMRI is sensitive to neuronal activity in cortical columns when using differential techniques, opening up the possibility of mapping specialized populations of neurons in humans that are not accessible to electrophysiological or other methods of invasive mapping.

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