Vision Science 2 - Exam 1 Material

Neurophysiology of Binocular Vision, Monocular and Binocular Visual Direction

What are the 5 prerequisites for binocular single vision?

1) Normal visual pathways with overlapping monocular fields

2) Binocular Neurons

3) Normal retino-cortical correspondence

4) Precise neuromuscular coordination

5) Equal image size and clarity

Retinal correspondence is a _______ phenomenon

Binocular

LGN layers 2,3, and 5 receive input from the _______ eye

ipsilateral

The four dorsal layers 3-6 receive input from _____ cells

parvo

The two ventral layers 1-2 receive input from ____ cells

magno

Parvo layers of the LGN project to layer __-__-____ of the primary visual cortex

4-C-beta

Magno layers of the LGN project to layer __-__-____ of the primary visual cortex

4-C-alpha

The ____ _____ carries magnocellular input and ends in the ____ ______ cortex

The Dorsal Stream carries magnocellular input and ends in the Posterior Parietal cortex

The ____ _____ carries parvocellular input and ends in the ____ ______ cortex

The Ventral Stream carries parvocellular input and ends in the infero-temporal cortex

Cells in each layer of the LGN have _______ receptive fields

Monocular

LGN is a ______ structure (neurons receive input from __ eye(s)

monocular; one

In the dorsal-ventral direction (aka Projection Column), what changes is the _____ ___ ______.

Receptive fields remain in the _____ _____ of the visual field

eye of origin; same location

Retinotopic Mapping of the LGN: Fovea is represented ________ and ________

centrally and posteriorly

Retinotopic Mapping of the LGN: Peripheral field is represented ________ and ________

laterally and anteriorly

Retinotopic Mapping of the LGN: Inferior field represented ______

superiorly

Retinotopic Mapping of the LGN: Superior field represented ________

inferiorly

LGN is essentially a ______ structure

monocular

Some LGN neurons show a modulated response when stimulated _______; These interactions are mostly ______ in nature

Binocularly; Inhibitory

Striate cortical neurons in layer IV of the striate cortex that receive the geniculate inputs are completely ______

monocular

The neurons ____ ____ _____ are the first, true binocular neurons

neurons outside layer IV

binocular neurons have receptive fields in ____ _____ and show a modulated response to a binocular stimulus

receptive fields in both eyes

A binocular neuron can show ____, _____, or sometimes ______ depending on whether its response to a binocular stimulus is greater than, equal tom or less than the sum of responses to monocular stimuli

Facilitation, Summation, or Inhibition

All (disparity detectors/ binocular neurons) are (disparity detectors/ binocular neurons) but not all (disparity detectors/ binocular neurons) are (disparity detectors/ binocular neurons)

All disparity detectors are binocular neurons but not all binocular neurons are disparity detectors

_____ _____ are binocular neurons in the visual cortex that are sensitive to disparity (very sensitive to positional differences in corresponding retinal image features in the two eyes)

Disparity Detectors

_____ ______ help determine whether the object is farther or nearer than fixation

Disparity Detectors

_____ _____ ______ are most responsive to stimuli with zero disparity

Tuned Excitatory Cells

_____ _____ ______ are most responsive to targets on the horopter

Tuned Excitatory Cells

What kind of disparity cell?

Tuned Excitatory Cells

What kind of disparity cell?

Tuned Inhibitory Cells

_______ ______ ______ have inhibited response for targets with zero disparity

Tuned Inhibitory Cells

_______ ______ ______ have highest response for targets off the horopter

Tuned Inhibitory Cells

What kind of disparity cell?

Near Cells

____ _____ respond to a range of crossed disparities

Near Cells (untuned)

____ _____ respond to a range of uncrossed disparities

Far Cells (untuned)

What kind of disparity cell?

Far Cells (Untuned)

_____ and _____ cells (_____) form the basis for coarse stereopsis

Near and Far Cells (Untuned)

_____ and _____ cells (_____) form the basis for fine stereopsis

Excitatory and Inhibitory cells (Tuned)

Fine Stereopsis is _____cellular function

parvo

Fine Stereopsis responds to (small/large) disparities ( <___ arc mins)

small disparities ( < 30 arc mins)

Fine Stereopsis responds to (high/ low) spatial frequencies ( >__cpd)

high spatial frequencies ( >3 cpd)

Fine Stereopsis responds to (high/ low) temporal frequencies; (slow/ fast) moving targets

low temporal frequencies; slow moving targets

Fine Stereopsis involves (foveal/ peripheral) vision

foveal

Fine Stereopsis has a latency of ____ ms

250 ms

Coarse Stereopsis is _____cellular function

magno

Coarse Stereopsis responds to (small/large) disparities ( >___ arc mins)

Large Disparities; > 30 arc mins

Coarse Stereopsis responds to (high/ low) spatial frequencies

low

Coarse Stereopsis responds to (high/ low) temporal frequencies

high

Coarse Stereopsis has a latency of ____ ms

125

Area V-2 has (large/ small) receptive fields

large

Area V-2 has (little/ many) disparity detectors

many

Cytochrome oxidase staining of area V-2 reveals ____ ___, ____ ____, and ______

Thick Stripes, Thin Stripes, Interstripes

How do we have stereopsis at the center of the visual field?

along the midline, there is some overlap of temporal & nasal fibers/ cross over at the chiasm

This overlap supports fine stereopsis in the center

At the ____ (and only at the ____), there is additional crossing over from one half of the cortex to the other

midline

The _____ pathway supports Coarse Stereopsis

Callosal pathway

To determine the location of a target in space, the 3 sources of information required are:

Relative Position/ Relative Distance (Retinocentric/ Oculocentric Direction)

Absolute Distance

Egocentric Point of Reference

______ or ______ _______ is a physical metric of the target location expressed relative to the fovea of the viewing eye (and is eye specific)

Retinocentric or Oculocentric Direction

The fovea is associated with a _____ oculocentric direction. All other positions are expressed relative to the ____ ____ _____

fovea is associated with a ZERO oculocentric direction

All other positions are expressed relative to the foveal oculocentric direction

The ___ ____ is a virtual line in physical space that connects the physical target (via the nodal point) to its respective retinal image

Visual Line

Each visual line is associated with a unique _____/______ ____ (or _____) in each ______

unique oculocentric/ retinocentric value (or direction) in each eye

Each oculocentric/ retinocentric direction of the visual line is expressed in physical units relative to the ______ (usually in angular units) of the viewing eye

Fovea

assuming a normal visual system…

____ Visual Lines are associated with Foveal images

Primary Visual Lines

assuming a normal visual system…

Primary Visual Lines are associated with a oculocentric/ retinocentric value = ______

zero

assuming a normal visual system…

____ Visual Lines are associated with Non-foveal images

Secondary Visual Lines

assuming a normal visual system…

Secondary Visual Lines are associated with a oculocentric/ retinocentric value = ______ expressed relative to the _________

a non-zero value expressed relative to the Primary Visual Line

Physiological Diplopia and Hering’s Window Experiment are examples which illustrate that ____ ____ ______ ≠ _____ _____ _____

Physical Direction Input ≠ Perceived Direction Output

Hering’s Window Experiment proved that depending on the viewing situation, the perceived location of targets ___ ____ ______ ___ _____ _____ _____

Hering’s Window Experiment proved that depending on the viewing situation, the perceived location of targets can differ considerably from their physical locations

Hering’s Window Experiment proved that perceived locations of targets seem to correspond to ___ ____ ____ ____ _____ ___ __ _____ ____ __ _____ ______

Hering’s Window Experiment proved that perceived locations of targets seem to correspond to some virtual reference point other than the anatomical position of the eyes

Observations of Hering’s Window Experiment suggest that ____ _____ of oculocentric directions are processed further to produce _____ _____ of directions relative to a virtual reference point

Observations of Hering’s Window Experiment suggest that Physical Inputs of oculocentric directions are processed further to produce Perceived Output of directions relative to a virtual reference point

Wells (1792) and Hering (1879) have elucidated laws or principles by which the visual system combines the _____ inputs of direction in each eye into a ______-______ output

Wells (1792) and Hering (1879) have elucidated laws or principles by which the visual system combines the physical inputs of direction in each eye into a perceptual-direction output

Fundamental Law I of visual direction:

The perceived direction of all targets are judged from the ____ _____ ____ (or the ____ _____)

cyclopean reference point (cyclopean eye)

Fundamental Law II(a) of visual direction:

a) all targets that lie on the _____ _____ ______ will be perceived as lying on a primary visual direction

a) all targets that lie on the primary visual line will be perceived as lying on a primary visual direction

Fundamental Law II(b) of visual direction:

b) If two targets lie on the same _____ _____, then they will always share the same visual direction

b) If two targets lie on the same visual line, then they will always share the same visual direction

Fundamental Law III(a) of visual direction:

a) all targets that lie on ____ ____ ____ will be perceived as lying on secondary visual directions which also connect to the cyclopean eye

a) all targets that lie on secondary visual lines will be perceived as lying on secondary visual directions which also connect to the cyclopean eye

Fundamental Law III(b) of visual direction:

b) The angle between a given _____ ____ ______ and the ____ ____ ____ within a given eye (i.e. its ____ _____) will be equal to the perceived angular separation between the primary visual direction and the respective secondary visual direction

b) The angle between a given secondary visual line and the primary visual line within a given eye (i.e. its oculocentric directions) will be equal to the perceived angular separation between the primary visual direction and the respective secondary visual direction

Whether viewing with one eye or both eyes, all targets are localized as though ___ ___ ____ ___ ___ ____ ____ ____ placed midway between the ______ _____ ______

Whether viewing with one eye or both eyes, all targets are localized as though we are viewing though a third imaginary eye placed midway between the two anatomical eyes

The exact location of the cyclopean eye is detectable, but is thought to lie in the median plane at the level of the corneal plane for ____ ____ ____

level of the corneal plane for fixed head viewing

The cyclopean eye acts as the center of reference for all _____ location of targets relative to the observer (aka egocentric or head-centric localization)

perceived

All visual lines transfer to the cyclopean eye as ____ _____

visual directions

All ____ directions are expressed relative to the _____ ____. These are termed ____ _____

All perceived directions are expressed relative to the cyclopean eye. These are termed visual directions

The ____ / ____ ____ ____ is an imaginary line joining the cyclopean eye to the point of intersection of the primary visual lines of the R/L eyes

primary/ principal visual direction

The primary/ principal visual direction represents the _____ direction of a fixated target relative to the cyclopean eye

perceived

Targets that share the same visual direction will be perceived as occupying the same direction in space relative to___ _____

relative to the observer

lines connecting non-fixated targets, nodal points, and the retina are termed ___ ___ ___

secondary visual lines

Secondary visual direction represents the perceived direction of a ____-____ _____ relative to the observer

non-fixated target

α?

α’?

α: oculocentric direction of B

α’: visual direction of B

α = α’

What does the Fundamental Law III(b) of visual direction depend on?

(IIIb) The angle between a given secondary visual line and the primary visual line within a given eye (i.e. its oculocentric directions) will be equal to the perceived angular separation between the primary visual direction and the respective secondary visual direction

Sampling grain of receptive fields

The perceived separation between two targets will be resolved at the ____, but not at the ____ _____

resolved at the fovea, but not at the retinal periphery

Violation to Fundamental Law III(b) of visual direction:

each ____ ____ is associated with a unique perceptual direction tag

→ difference in _____ ____ are equal, but their ____ _____ will not be equal

each receptive field is associated with a unique perceptual direction tag

→ difference in oculocentric directions are equal, but their perceived separation will not be equal

Fundamental Law IV of visual direction:

aka Law of _____ ____ _____

Law of Identical Visual Directions

Fundamental Law IV of visual direction:

under binocular viewing conditions, every visual line in one eye within the binocular visual field has a ____ ____ ____ in the other eye which will share (or transfer to) the same or identical _____ ____

under binocular viewing conditions, every visual line in one eye within the binocular visual field has a corresponding visual line in the other eye which will share (or transfer to) the same or identical visual direction

According to Law IV of visual direction, both the right and left primary visual lines will transfer to a common primary visual direction emanating from the cyclopean eye, therefore primary visual lines share a(n) _______ _____ ______

identical visual direction

While fixating a target (F), it is possible to find a target location (B) such that its right and left secondary visual lines transfer to the same secondary visual line.

Such a situation will arise only if non-fixated targets are located on the ______

Horopter

The “retinal" elements” in each eye stimulated by a given pair of corresponding visual lines are termed ______ _____

Corresponding Points

____ _____ are retino-cortical elements in each eye that are associated with identical visual directions

Corresponding Points

In normal human binocular systems, the fovea of the L & R eyes are considered _____ points

corresponding

If an image stimulates corresponding points in each eye, then that image will be perceived as _____ or ____ (ie: ____ visual directions)

single or overlapping (same visual directions)

If an image stimulates non-corresponding points in each eye, then that image will be perceived as _____ or ____ (ie: ____ visual directions)

Double or Diplopic (different visual directions

____ _____ are retino-cortical elements in each eye that are associated with different visual directions

Non-Corresponding Points

If corresponding points are distributed congruently across the retina of each eye, then all targets that stimulate these corresponding points will fall on a _____ passing through the ____ point and ____ point of each eye.

This is called _____/_____ _____ or the _____-_____ _____

If corresponding points are distributed congruently across the retina of each eye, then all targets that stimulate these corresponding points will fall on a circle passing through the fixation point and nodal point of each eye.

This is called Theoretical/ Geometric Horopter or the Veith-Muller Circle

The locus of all targets in space that stimulate corresponding points in termed the ______

Horopter