Physiology Of Behavior - Chapter 6 - Vision

Front 1

What is a sensory receptor?

Back 1

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

Front 2

What is sensory transduction?

Back 2

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

Front 3

What is a receptor potential?

Back 3

A slow, graded electrical potential produced by a receptor cell in response to a physical stimulus.

Front 4

What is hue?

Back 4

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

Front 5

What is brightness?

Back 5

One of the perceptual dimensions of color; intensity.

Front 6

What is saturation?

Back 6

One of the perceptual dimensions of color; purity.

Front 7

What is vergence movement?

Back 7

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

Front 8

What is saccadic movement?

Back 8

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

Front 9

What is pursuit movement?

Back 9

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

Front 10

What is accommodation?

Back 10

Changes in the thickness of the lens of the eye, accomplished by the ciliary muscles, that focus images of near or distant objects on the retina.

Front 11

What is the retina?

Back 11

The neural tissue and photoreceptive cells located on the inner surface of the posterior portion of the eye.

Front 12

What is a rod?

Back 12

One of the receptor cells of the retina; sensitive to light of low intensity.

Front 13

What is a cone?

Back 13

One of the receptor cells of the retina; maximally sensitive to one of three different wavelengths of light and hence encodes color vision.

Front 14

What is a photoreceptor?

Back 14

One of the receptor cells of the retina; transduces photic energy into electrical potentials.

Front 15

What is the fovea?

Back 15

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.

Front 16

What is the optic disk?

Back 16

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.

Front 17

What is a bipolar cell?

Back 17

A bipolar neuron located in the middle layer of the retina, conveying information from the photreceptors to the ganglion cells.

Front 18

What is a ganglion cell?

Back 18

A neuron located in the retina that receives visual information from bipolar cells; its axons give rise to the optic nerve.

Front 19

What is a horizontal cell?

Back 19

A neuron in the retina that interconnects adjacent photoreceptors and the outer processes of the bipolar cells.

Front 20

What is an amacrine cell?

Back 20

A neuron in the retina that interconnects adjacent ganglion cells and the inner processes of the bipolar cells.

Front 21

What is the lamella?

Back 21

A layer of membrane containing photopigments; found in rods and cones of the retina.

Front 22

What is a photopigment?

Back 22

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

Front 23

What is opsin?

Back 23

A class of protein that, together with retinal, constitutes the photpigments.

Front 24

What is retinal?

Back 24

A chemical synthesized from vitamin A; joins with an opsin to form a photopigment.

Front 25

What is rhodopsin?

Back 25

A particular opsin found in rods.

Front 26

What is transducin?

Back 26

A G protein that is activated when a photon strikes a photopigment; activates phosphodiesterase molecules, which destroy cyclic GMP and close cation channels in the photoreceptor.

Front 27

What is the dorsal lateral geniculate nucleus?

Back 27

A group of cell bodies within the lateral geniculate body of the thalamus; receives inputs from the retina and projects to the primary visual cortex.

Front 28

What is the magnocellular layer?

Back 28

One of the inner two layers of cells in the dorsal lateral geniculate nucleus; transmits information necessary for the perception of form, movement, depth, and small differences in brightness.

Front 29

What is the parvocellular layer?

Back 29

One of the four outer layers of cells in the dorsal lateral geniculate nucleus; transmits information necessary for perception of color and fine details.

Front 30

What is the calcarine fissure?

Back 30

A horizontal fissure on the inner surface of the posterior cerebral cortex; the location of the primary visual cortex.

Front 31

What is the striate cortex?

Back 31

The primary visual cortex.

Front 32

What is the optic chiasm?

Back 32

A cross-shaped connection between the optic nerves, located below the base of the brain, just anterior to the pituitary gland.

Front 33

What is the receptive field?

Back 33

That portion of the visual field in which the presentation of visual stimuli will produce an alteration in the firing rate of a particular neuron.

Front 34

What is protanopia?

Back 34

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

Front 35

What is deuteranopia?

Back 35

An inherited form of defective color vision in which hues with short wavelengths are confused; "blue" cones are either lacking or faulty.

Front 36

What is a negative afterimage?

Back 36

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.

Front 37

What are complementary colors?

Back 37

Colors that make white or gray when mixed.

Front 38

What is a simple cell?

Back 38

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

Front 39

What is a complex cell?

Back 39

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 peripendicularly to its orientation.

Front 40

What is sine-wave grating?

Back 40

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

Front 41

What is spatial frequency?

Back 41

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

Front 42

What is retinal disparity?

Back 42

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.

Front 43

What is the cytochrome oxidase (CO) blob?

Back 43

The central region of a module of the primary visual cortex, revealed by a stain for cytochrome oxidase; contains wavelength-sensitive neurons; part of the parvocellular system.

Front 44

What is ocular dominance?

Back 44

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

Front 45

What is blindsight?

Back 45

The ability of a person to reach for objects located in his or her "blind" field; occurs after damage restricted to the primary visual cortex.

Front 46

What is the extrastriate cortex?

Back 46

A region of visual association cortex; receives fibers from the striate cortex and from the superior colliculi and projects to the inferior temporal cortex.

Front 47

What is color constancy?

Back 47

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

Front 48

What is achromatopsia?

Back 48

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

Front 49

What is the inferior temporal cortex?

Back 49

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

Front 50

What is visual agnosia?

Back 50

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

Front 51

What is apperceptive visual agnosia?

Back 51

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

Front 52

What is prosopagnosia?

Back 52

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

Front 53

What is associative visual agnosia?

Back 53

Inability to identify objects that are perceived visually, even thought the form of the perceived object can be drawn or matched with similar objects.

Front 54

What is the pulvinar?

Back 54

A large thalamic nucleus that projects to the visual association cortex and may play a role in compensating for eye and head movements.

Front 55

What is Balint's syndrome?

Back 55

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

Front 56

What optic ataxia?

Back 56

Difficulty in reaching for objects under visual guidance.

Front 57

What is ocular apraxia?

Back 57

Difficulty in visual scanning.

Front 58

What is simultanagnosia?

Back 58

Difficulty in perceiving more than one object at a time.