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Multiple Retinotopic Maps of the Visual Field

image Ferrari-458-Italia-Spider-Speeding-Wallpaper-1920x1080.jpg When we see a red Ferrari zooming past, the information is reassembled from a map of the colors, a map for motion processing and a map for object identification. These are Retinotopic Maps. Christof Koch uses the red Ferrari zooming past to illustrate the Binding problem in his Glossary of Terms.

From Baars 2013:

" Cortico-thalamic arrays are mutually linked via spatially consistent “labeled lines.” For example, the small foveal center of each retina subtends only 2–4° of visual arc, with about one million densely packed cones and rods. Foveal patches can be roughly considered to be 1000 × 1000 arrays of light receptors that are echoed point-to-point in retinal ganglion cells, whose axons make up the optic nerve. Ganglion cells are mirrored in the visual thalamus (LGN), which transmit signals point-to-point to V1.

Labeled line coding implies that the relative locations of neurons are preserved in higher level retinotopic maps. Beyond V1 visuotopic maps preserve a sparser copy of the visual field, while cellular receptive fields increase in size and decrease in spatial resolution. Spatiotopic mapping is regular and systematic throughout the C-T complex. . . .

image Ferrari458lines.jpg

Starting with LGN, all spatiotopic pathways become bidirectional. Successive arrays pick up visual features like spatial frequency, contrast, edge orientation, gestalt properties, hue, motion, and object identity. Higher level properties like object permanence, size constancy, color constancy, shape from shading, face and object recognition, scene analysis, movements, causality, and event organization, all require complex interactions among 40 or more spatiotopic arrays. The sight of a red traffic light must remain stable in spite of differences in reflectance, observer motion, background clutter, and changes in sunlight." (end Baars 2013)

I am not going to attempt to explain the visual cortex. This Chapter is great!. Collin Ware has a wonderful simple description of the various parts of the visual cortex and how they can be exploited. And Wikipedia:   Visual_space,   Visual_cortex

Instead, I am proposing that we do not need to consider the binding problem for vision. If all of the retinotopic maps are connected via “labeled lines”, then the cortico-thalamic complex is presented with pixels that are naturally bound. The given pixel knows it is red; knows it is moving; knows it is a Ferrari. I know Dehaene has said that the binding problem may just disappear as we learn more. Anyway, without further ado, here are some pixels that help me understand the visual cortex's ability to see the red Ferrari zooming past.

image Ferrari458color.jpg
Color Map: V4


image Ferrari458object.jpg
Object Map: inferior temporal cortex (IT)


image Ferrari458motion.jpg
Motion Detector Map: V5/MT

Zooming Past


The Three Retinotopic Maps bound together:   Color (V4),   Object (inferior temporal cortex) and  Motion (V5/MT)

BTW, This is similar to high end computer graphics where the window on the screen is a color buffer, then there is a depth buffer to remember how far away things are and for some application there may be an Pat Hanrahan for SIGGRAPH 1990)

Animated GIF: photoshop image hacking to create the motion, color, object and lines image from the original. Then I used VRML for the 3D, rendering 16 images with Instant Reality. Brought to you by Posterette

Retinotopic, Visuotopic and Spatiotopic

I have not clarified what retinotopic, spatiotopic, visuotopic, topographic and/or anisotropic really mean. Actually, I know what it is to be anisotropic. And I have a good feel for topographic, too. For the others, my best guess:
- Retinotopic - well defined - a spot on the retina corresponds to a spot on the map. (must be 2D, right?)
- Visuotopic - a spot in the visual field corresponds to a spot on the map. ( more than 2D ? )
- Spatiotopic - the frame of reference may be outside the body.

On Jul 7, 2014, at 12:08 AM, Adam Greenberg wrote:

From my standpoint, in most cases of visual cognition, these four words wind up meaning the same thing. But, strictly speaking, visuotopic is related more to retinotopic, but doesn't necessarily have to follow the mapping of the retina. For example, in the case of parietal cortex, the visuotopic mapping is a map of visual space, but decidedly not retinotopic. Spatiotopic I think of as more general. So, both visual cortex retinotopy and parietal cortex visuotopy are both spatiotopic, as well. They follow some sort of mapping of space on to cortex. But, in principle, one could have a spatiotopic map of auditory information (since our auditory system also codes the spatial locations from which sounds are emitted).

In sum, it's a hierarchy of sorts: topographic > spatiotopic > visuotopic > retinotopic.

On Jul 11, 2014, at 7:18 AM, Justin Gardner wrote:

Visuotopic just means that you measured the relationship between stimuli in visual space and cortical topography. It does not test the reference frame which can be anchored to the retina, to the position of the head or to an arbitrary location in outside space (spatiotopic). You may want to read a review article from Richard Andersen's lab if these issues are not clear.
Visuotopic cortical connectivity underlying attention revealed with white-matter tractography
Visual attention selects behaviorally relevant information for detailed processing by resolving competition for representation among stimuli in retinotopically organized visual cortex. The signals that control this attentional biasing are thought to arise in a frontoparietal network of several brain regions, including posterior parietal cortex. Recent studies have revealed a topographic organization in the intraparietal sulcus (IPS) that mirrors the retinotopic organization in visual cortex, suggesting that connectivity between these regions might provide the mechanism by which attention acts on early cortical representations.

From Retinotopic Maps, Spatial Tuning, and Locations of Human Visual Areas in Surface Coordinates Characterized with Multifocal and Blocked fMRI Designs

The two methods yielded consistent retinotopic maps in the visual areas V1, V2, V3, hV4, and V3AB. In the higher-level areas IPS0, VO1, LO1, LO2, TO1, and TO2, retinotopy could only be mapped with the blocked stimulus presentation.
Maps of Visual Space in Human Occipital Cortex Are Retinotopic, Not Spatiotopic.
We experience the visual world as phenomenally invariant to eye position, but almost all cortical maps of visual space in monkeys use a retinotopic reference frame, that is, the cortical representation of a point in the visual world is different across eye positions. It was recently reported that human cortical area MT (unlike monkey MT) represents stimuli in a reference frame linked to the position of stimuli in space, a “spatiotopic” reference frame. We used visuotopic mapping with blood oxygen level-dependent functional magnetic resonance imaging signals to define 12 human visual cortical areas, and then determined whether the reference frame in each area was spatiotopic or retinotopic. We found that all 12 areas, including MT, represented stimuli in a retinotopic reference frame. Although there were patches of cortex in and around these visual areas that were ostensibly spatiotopic, none of these patches exhibited reliable stimulus-evoked responses. We conclude that the early, visuotopically organized visual cortical areas in the human brain (like their counterparts in the monkey brain) represent stimuli in a retinotopic reference frame.
. . .
We conclude that the early, visuotopically organized visual cortical areas in the human brain (like their counterparts in the monkey brain) represent stimuli in a retinotopic reference frame.
Going from a Retinotopic to a Spatiotopic Coordinate System for Spatial Attention:
The past two decades have seen dramatic advancements in our knowledge about the cortical representation of the visual world. Research has revealed an increasing number of topographic maps representing the various parameters that can be extracted from visual input, such as orientation, spatial frequency, or color. Some represent space finely, others coarsely, but any topographic map must account for a principal problem for its representation of space: how to cope with saccades. Should the map represent items independently of where they fall on the retina, or update to take account of the saccade? We might think of these two alternative ways of representing the visual world as being either world centered, with the map being invariant to where one fixates at any one moment, or eye centered, with the map representing the moment-by-moment location of the item on the retina. In vision research, these two alternatives are typically labeled as spatiotopic and retinotopic, respectively.

. . . the human visual system uses both spatiotopic and retinotopic mapping. For example, primary visual cortex demonstrates a near-perfect retinotopic representation of the visual world, whereas portions of area MT contain a spatiotopic coordinate system of motion . . .

Spatiotopic perceptual maps in humans: evidence from motion adaptation
How our perceptual experience of the world remains stable and continuous despite the frequent repositioning eye movements remains very much a mystery. One possibility is that our brain actively constructs a spatiotopic representation of the world, which is anchored in external—or at least head-centred—coordinates.

From Retinotopic Maps, Spatial Tuning, and Locations of Human Visual Areas in Surface Coordinates Characterized with Multifocal and Blocked fMRI Designs
". . . retinotopic maps in the visual areas V1, V2, V3, hV4, and V3AB. In the higher-level areas IPS0, VO1, LO1, LO2, TO1, and TO2, retinotopy could only be mapped . . ."

created 2014.07.05 YON