Vision

Question 1

sensory receptors

–

Answer 1

A specialized neuron that detects a particular category of physical events.


Question 2

receptive field

Answer 2

the region of space where stimulation causes a

cell to fire.

Question 3

sensory transduction

Answer 3

The process by which sensory stimuli are transduced into slow, graded receptor potentials.


Question 4

Accommodation

Answer 4

is the process of adjusting the shape of the lens so that light emitted from a point on an object converges to a point on the retina

Question 5

Vergence

Answer 5

is the cooperative movement of the eyes, which ensures that the image of an object falls on identical portions of both retinas.


Question 6

saccadic movement

Answer 6

The rapid, jerky movements of the eyes used in scanning a visual scene.


Question 7

pursuit movement

Answer 7

The movement that the eyes make to maintain an image of a moving object on the fovea.

Question 8

fovea

Answer 8

The region of the retina that mediates the most acute vision of birds and higher mammals. Color-sensitive cones constitute the only type of photoreceptor found in the fovea.
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Question 9

periphery

Answer 9

the area outside of the foveal region that mediates low-acuity peripheral vision. Contains a mixture of rods and cones

Question 10

optic disk

Answer 10

The location of the exit point from the retina of the fibers of the ganglion cells that form the optic nerve; responsible for the blind spot.

Question 11

Cell is the Retina 5

Answer 11

photoreceptor
(One of the receptor cells of the retina; transduces photic energy into electrical potentials.
)
bipolar cell
(A bipolar neuron located in the middle layer of the retina, conveying information from the photoreceptors to the ganglion cells.
)
ganglion cell
(A neuron located in the retina that receives visual information from bipolar cells; its axon give rise to the optic nerve.
)
horizontal cell
(A neuron in the retina that interconnects adjacent photoreceptors and the outer processes of the bipolar cells.
)
amacrine cell
(A neuron in the retina that interconnects adjacent ganglion cells and the inner processes of the bipolar cells.)

Question 12

photopigment

Answer 12

A protein dye bonded to retinal, substance derived from vitamin A; responsible for transduction of visual information.

-opsin
A class of protein that, together with retinal, constitutes the photopigments.

-retinal
A chemical synthesized from vitamin A; join with opsin to form a photopigment.

-rhodopsin
A particular opsin found in rods.

Question 13

LGN layers 3

Answer 13

magnocellular layer
The inner two layers of neurons in the dorsal lateral geniculate nucleus; transmit information necessary for the perception of form, movement, depth, and small differences in brightness to the primary visual cortex.

parvocellular layers
The four outer layers of neurons in the dorsal lateral geniculate nucleus; transmit information necessary for perception of color and fine details to the primary visual cortex.


koniocellular layer
One of the sublayers of neurons in the dorsal lateral geniculate nucleus bound to each of the magnocellular and parvocelllar layers; transmits information from short-wavelength (“blue”) cones to the primary visual cortex.

Question 14

colour 3 aspects

Answer 14

-hue
One of the perceptual dimensions of color; the dominant wavelength.

-brightness
One of the perceptual dimensions of color; intensity.

saturation
One of the perceptual dimension of color; purity.

Question 15

negative afterimage

Answer 15

The image seen after a portion of the retina is exposed to an intense visual stimulus; consists of colors complementary to those of the physical stimulus.


Question 16

complimentary colors

Answer 16

Colors that make white or gray when mixed together

Question 17

colour blindness 3

Answer 17

-protanopia
An inherited form of defective color vision in which red and green hues are confused; “red” cones are filled with “green” cone opsin.

-deuteranopia
An inherited form of defective color vision in which red and green hues are confused; “green” cones are filled with “red” cone opsin
-tritanopia
An inherited form of defective color vision in which hues with short wavelengths are confused; “blue” cones are either lacking or faulty.


Question 18

simple cell

Answer 18

An orientation-sensitive neuron in the striate cortex whose receptive field is organized in an opponent fashion.


Question 19

complex cell

Answer 19

A neuron in the visual cortex that responds to the presence of a line segment with a particular orientation located within its receptive field, especially when the line moves perpendicular to its orientation.


Question 20

hypercomplex cell

Answer 20

A neuron in the visual cortex that responds to the presence of a line segment with a particular orientation that ends at a particular point within the cell’s receptive field.

Question 21

sine-wave grating

Answer 21

A series of straight parallel bands varying continuously in brightness according to a sine-wave function, along a line perpendicular to their lengths.


Question 22

spatial frequency

Answer 22

The relative width of the bands in a sine-wave grating, measured in cycles per degree of visual angle.


Question 23

Cytochrome oxidase (CO) blob:

Answer 23

The central region of a module of primary visual cortex, revealed by a stain for cytochrome oxidase; contains neurons sensitive to colour and high spatial frequency; part of the parvocellular system.


Question 24

Interblob region:

Answer 24

The surround region of a CO blob, contains neurons sensitive to movement, lower spatial frequency (goes up with distance from blob center) and binocular disparity. These neurons are largely insensitive to wavelength.

Question 25

ocular dominance

Answer 25

The extent to which a particular neuron receives more input from one eye than from the other.

Question 26

retinal disparity

Answer 26

The fact that points on objects located at different distances from the observer will fall on slightly different locations on the two retinas; provides the basis for stereopsis.

Question 27

extrastriate cortex

Answer 27

A region of visual association cortex; receives fibers from the striate cortex and from the superior colliculi and projects to dorsal and ventral visual streams.


Question 28

dorsal stream

Answer 28

A system of interconnected regions of visual cortex involved in the perception of spatial location, beginning with the striate cortex and ending with the posterior parietal cortex.

Question 29

ventral stream

Answer 29

A system of interconnected regions of visual cortex involved in the perception of form, beginning with the striate cortex and ending with the inferior temporal cortex.


Question 30

inferior temporal cortex

Answer 30

In primates the highest level of the ventral stream of the visual association cortex; located on the inferior portion of the temporal lobe.

Question 31

agnosia 4

Answer 31

-visual agnosia
Deficits in visual perception in the absence of blindness; caused by brain damage.


-apperceptive visual agnosia
Failure to perceive objects, even though visual acuity is relatively normal.


-associative visual agnosia
Inability to identify objects that are perceived visually, even though the form of the perceived object can be drawn or matched with similar objects.


-prosopagnosia
Failure to recognize particular people by the sight of their faces.

Question 32

face body scene?

Answer 32

-fusiform face area (FFA)
A region of the visual association cortex located in the inferior temporal cortex; involved in perception of faces and other complex objects that require expertise to recognize.


-extrastriate body area (EBA)
A region of the visual association cortex located in the lateral occipitotemporal cortex; involved in perception of the human body and body parts other than faces.


-parahippocampal place area (PPA)
A region of the medial temporal cortex, involved in perception of particular places (“scenes”).

Question 33

color constancy

Answer 33

The relatively constant appearance of the colors of objects viewed under varying lighting conditions.


Question 34

cerebral achromatopsia

Answer 34

Inability to discriminate among different hues; caused by damage to area V8 of the visual association cortex.

Question 35

optic flow

Answer 35

The complex motion of points in the visual field caused by relative movement between the observer and environment; provides information about the relative distance of objects from the observer and of the relative direction of movement.

Question 36

intraparietal sulcus (IPS)

Answer 36

The end of the dorsal stream of the visual association cortex; involved in perception of location, visual attention, and control of eye and hand movements.

Question 37

Damage to dorsal stream:

• simultanagnosia
• ocular apraxia
• akinetopsia
• Balint’s syndrome
• optic ataxia

Answer 37

-simultanagnosia
Difficulty in perceiving more than one object at a time.

-ocular apraxia
Difficulty in visual scanning.

-akinetopsia
Inability to perceive movement, caused by damage to area V5 (also called MST) of the visual association cortex.

-Balint’s syndrome
A syndrome caused by bilateral damage to the parieto-occipital region; includes optic ataxia, ocular apraxia, and simultanagnosia.

-optic ataxia
Difficulty in reaching for objects under visual guidance.