Show Reference: "Vision and Brain: How We Perceive the World"

Vision and Brain: How We Perceive the World (14 September 2012) by James V. Stone
@book{stone-2012,
    author = {Stone, James V.},
    day = {14},
    edition = {1},
    howpublished = {Paperback},
    isbn = {0262517736},
    keywords = {biology, eye, visual, visual-processing},
    month = sep,
    posted-at = {2013-04-08 08:42:47},
    priority = {2},
    publisher = {The MIT Press},
    title = {Vision and Brain: How We Perceive the World},
    url = {http://www.amazon.com/exec/obidos/redirect?tag=citeulike07-20\&path=ASIN/0262517736},
    year = {2012}
}

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All visual areas from V1 to V2 and MT are retinotopic.

The eye suffers from

  • chromatic aberration
  • optical imperfections
  • the fact that photo receptors are behind ganglia and blood vessels

Different wavelengths of light are refracted differently. Therefore, the focal point of the lens is never the same for all wavelengths. Thus, any object can only be perfectly focused in one wavelength partial images in other wavelengths are always blurred. This effect is called chromatic aberration.

Cones are color-sensitive, rods aren't.

The optic nerve does not have the bandwidth to transmit all the light receptors' activities. Some compression occurs already in the eye.

Short-range inhibition happens in the horseshoe crab compound eye: neighbouring receptor units inhibit each other.

Ganglion cells in the retina connect the brain to a small, localized number of photoreceptors. The small population—or the region in space from which it receives incoming light— are called a ganglion cell's receptive field. They respond best either to patterns of high luminance in the center of that small population and low luminance at its periphery, or to the opposite pattern. Ganglion cells with the former characteristics are called "on-center" cells, the others "off-center" cells.

Simple center-surround receptive fields are selective of specific spatial frequencies. Other filters, like Gabor filters or linear combinations of simple center-surround receptive fields, can be selective for

Contrast sensitivity is an important feature of early visual processing.

Stone speaks of the 'conservative nature of evolution' which recycles solutions and applies them wherever they fit. According to this, it is likely that any mechanisms found in visual processing operate in many if not all places of the brain dealing with different but structurally similar functions.

Redundancy reduction, predictive coding, efficient coding, sparse coding, and energy minimization are related hypotheses with similar predictions. All these theories are reasonably successful in explaining biological phenomena.

More visual processing tends to occur in the retina the more important the result is (like detecting bugs for frogs or detecting foxes for rabbits) and the less complex the organism (like frogs and foxes).

LGN has six layers.

LGN is retinotopically organized.

Spatial frequency carries a lot of information about a visual image.

Magnocellular ganglion cells have large receptive fields.

The M-stream of visual processing is formed by magnocellular ganglion cells, the P-stream by parvocellular ganglion cells.

The M-stream is thought to deal with motion detection and analysis, while the P-stream seems to do be involved in processing color and form.

The part of the visual cortex dedicated to processing signals from the fovea is much greater than that dealing with peripheral signals.

LGN receives more feedback projections from V1 than forward connections from the retina.

Cells in inferotemporal cortex are highly selective to the point where they approach being grandmother cells.

There are cells in inferotemporal cortex which respond to (specific views on / specific parts of) faces, hands, walking humans and others.

"Constructing a mathematically precise account of the brain has the potential to change our view of how it works."

Computational theories of the brain account not only for how it works, but why it should work that way.