Fusion, Rivalry, and Suppression Flashcards
(41 cards)
where does fusion happen in the brain
where do we stop seeing monocularly in the brain
fusion happens in the visual cortex
stop seeing mono in layer 4C of the striate cortex
what are the 2 parts of fusion process
- sensory: images near corresp points are fused
2. motor: move eyes in or out to fuse images at diff distances
what are the 2 types of diplopia, which is abnormal
physiological: nonfixated objects off the horopter
pathological: seeing 2 of the image you are paying attentino to, NOT NORMAL
what is confusion
where is it most visible in
what does it usually accompnay
another name?
when you perceive 2 diff objects to be in the exact same place in the vf
- most visible in foveal vision
- usually accompanies diplopia
- aka binocular rivalry
what is panum’s area
an area on the retina of one eye wehre an image may be placed and still fuse w/ an image at a fixed location in the fellow eye
what is panum’s space
the region of 3D space where singleness is perceived
do all points fused in panum’s area appear in the same location in visual space
no-each diff pair of retinal points in PA creates a unique stereo depth and direction in visual space so there is no loss of spatial info w/ fusion
where is the horopter in panum’s space
in the middle
what is allelotropia
the oculocentric directions of fused images are averaged to form a cyclopean direction
-direction averaging process is influenced by ocular dominance
how is PA related to retinal eccentricity
PA size increases w/ retinal eccentricity
when patients report diplopia, where is it usually from
foveal
-it is not easily observed in peripheral vision
how does PA change in the periphery
increases as you move out to the periphery
what kind of motion increase the size of PA
target motion and patient motion
higher spatial freq (sharp edges) are associated w/ ____ PA size
smaller
what are the various sizes taht have been reported for foveal panum’s area?
using what kind of things?
2’ (woo, using fine bars)
6’ (ogle, using horopter rods)
15’ (mitchell, using small flashing spots)
how is PA shaped for very brief stimuli?
how is it shaped for long duration stimuli?
how is it shaped for static targets?
how is it shaped for foveal?
- round for brief
- PA diamter slightly increased vert and greatly increased horiz (3x) for long duration
- horizontal ellipse for static
- elliptical for foveal
how is panum’s area is strabismic patients
most constant strabismus have no fusion or panum area
why do patients w/ microtropia have single peripheral vision
-ocular misalignment is too large in microtropes to allow images to fall w/in normal panum’s area in the foveal macular area
how does PA develop in pts w/ constant microtrope strab
very large panum’s areas in the periphery
what is binocular summatino
a change of nonspatial quality of vision caused by binocular interaction
what are the possible levels of mathematical binocular summation
- facilitation: when stimulus is more than twice as bright OU than w/ one eye. 1+1>2
- complete summation: when stimulus is twice as bright OW
1+1=2 - partial summation: when stimulus is brighter OU
1+1=1.5 - zero summation: when stimulus is as bright OU
1+1=1 - inhibition: when stimulus is not as bright OU
1+1<1
what is most binocular summation in terms of math
zero summation or partial summation
how do eyes behave for dim scotopic images falling outside panum’s area
weak stimuli more detected w/ 2 eyes than 1 bc you get 2 changes of detection
how is binocular summation related in CFF, contrast threshold, and resolution threshold
CFF: goes up
contrast threshold: goes down
resolution threshold: goes down bc of contrast threshold
