Neuro psych Quiz 5

Question 1

What happens when you see something?

Answer 1

Light rays reflect off the object and strike your retina

Question 2

If you look at a picture, how doe the neurons in your brain represent it?

Answer 2

Neither right side up or upside down

Question 3

What is the law of specific nerve energies?

Answer 3

Each sensory neuron conveys a particular type of sensation, such as light or sound

Question 4

What makes the blind spot of the retina blind?

Answer 4

The optic nerve and blood vessels occupy this space leaving no room for receptors.

Question 5

Vision in the periphery of the retina has poor sensitivity to detail but great sensitivity to faint light. Why?

Answer 5

Towards the periphery, the retina has more convergence of input.

Question 6

Input to the human visual cortex comes from cones and rods ( by way of ganglion cells) in what proportion?

Answer 6

About 90% of input to the cortex comes from cones.

Question 7

Suppose you perceive something as red. According to the trichromatic theory, what is the explanation?

Answer 7

Light from the object has excited your long-wave-length cones more strongly than your other cones.

Question 8

If you stare at a white circle surrounded by a green background and then look at a white surface, you perceive a green circle surrounded by a red background. What does this observation imply about the opponent-process theory?

Answer 8

Opponent-process theory color perception depends on the visual cortex, not just the cells in the retina.

Question 9

An object that reflects all wavelengths equally ordinarily appears gray, but it may appear yellow, blue, or any other color, depending on what?

Answer 9

Contrast with surrounding objects

Question 10

Which theory most readily accounts for the observation described in question 9?

Answer 10

Retinex theory

Question 11

What evidence shows that color, such as greenness, is in the brain and not in the light itself?

Answer 11

Each wavelength excites a different set of cells in the visual cortex.

Question 12

What is the order of connections from receptors to visual cortex?

Answer 12

Receptors - bipolar cells - ganglion cells - lateral geniculate - visual cortex

Question 13

Axons from the nasal half of the retina go to the ——- hemisphere of the brain.

Answer 13

contralateral

Question 14

Axons from the temporal half of the retina go to the ——- hemisphere of the brain

Answer 14

ipsilateral

Question 15

When light strikes a receptor the effect is to —– the bipolar cells and —— the horizontal cells. The horizontal cells —- the bipolar cells.

Answer 15

1) excite
2) excite
3) inhibit

Question 16

If light strikes one receptor, the net effect is to —- the nearest bipolar cell and —- other bipolar cells to the side because of the contributions from — cells.

Answer 16

1) Excite
2) inhibit
3) horizontal

Question 17

Suppose light strikes the retina in a circle, surrounded by the dark. Which bipolar cells will show the greatest response, and which will show the least?

Answer 17

Bipolar connected to the receptors just inside the circumference of the circle respond most. Those connected to receptors just outside the circumference respond least.

Question 18

As we progress from bipolar cells to ganglion cells to later cells in the visual system, what happens to the size of receptive fields?

Answer 18

they become larger

Question 19

In contrast to parvocellular neurons, magnocellular neurons are more sensitive to…

Answer 19

movement

Question 20

If you were in a darkened room and researchers wanted to know whether you were having visual fantasies (without asking you), they could measure activity in which brain area?

Answer 20

The primary visual cortex

Question 21

What is meant by blindsight?

Answer 21

Some people with damage to the primary visual cortex accurately guess the location or other properties of objects they say they don’t see.

Question 22

How could a researchers determine whether a given neuron in the visual cortex is simple or complex?

Answer 22

If it responds to a stimulus in just one location, it is a simple cell. If it responds in several locations, it is a complex cell.

Question 23

What do cells within a column of the visual cortex have in common?

Answer 23

They respond best to lines in the same orientation.

Question 24

What is the evidence that certain types of feature detectors operate in the human visual cortex?

Answer 24

After you stare at a waterfall or other steadily moving display, you see stationary objects as moving in the opposite direction.

Question 25

If a kitten has one eye shut for its first few weeks of life, its visual cortex becomes insensitive to that eye. Why?

Answer 25

Activity from the active eye displaces synapses from the inactive eye.

Question 26

What early experience is necessary to maintain binocular input to the neurons of the visual cortex?

Answer 26

Cortical cells must usually receive simultaneous input from the two eyes.

Question 27

Why is it important to correct astigmatism early?

Answer 27

The visual cortex becomes more sensitive to the lines it sees best.

Question 28

If someone is born with dense cataracts on both eyes, and the cataracts are removed years later, which of these aspects of vision remain permanently impaired?

Answer 28

Perception of brightness and darkness.

Question 29

Within the visual system of the brain, the ventral stream is more important for —- and the dorsal stream is more important for —

Answer 29

1) Identifying objects
2) controlling movement

Question 30

Visual agnosia usually results from damage to which part of the cortex?

Answer 30

Temporal cortex

Question 31

What impairment is typical after damage to the fusiform gyrus?

Answer 31

Difficulty recognizing faces

Question 32

Which part of the visual cortex is most important for color vision, especially color constancy?

Answer 32

Area V4

Question 33

Why is it difficult to watch your own eyes move when looking in the mirror?

Answer 33

During saccadic eye movements, activity decreases in area MT.

Question 34

What was ibn al-Haythem’s evidence that we see only because light enters the eyes, not by sending out sight rays?

Answer 34

1) You can see distant objects such as as starts far faster than we could imagine sight rays reaching them.
2) When light strikes an object, we see only the light rays that reflect off the object and into the eyes.

Question 35

If someone electrically stimulated the auditory receptors in your ear, what would you perceive?

Answer 35

Because of the law of specific energies, you would perceive it as sound, not as shock

Question 36

If it were possible to flip your entire brain upside down, without breaking any of the connections to sense organs or muscles, what would happen to your perceptions of what you see, hear, and so forth?

Answer 36

Your perceptions would not change. Coding of auditory and visual information is not dependent on location. How you see something depends on which neurons are active.

Question 37

What is the opening in the center of the iris that light enters through called?

Answer 37

Pupil

Question 38

what focuses the light that enters the pupil?

Answer 38

the lens and cornea

Question 39

What is light projected to from the lens and cornea?

Answer 39

retina

Question 40

cells that get info from bipolar cells and send it to other bipolar, aminacrine, and ganglion cells?

Answer 40

Amacrine cells

Question 41

Are there more ganglion or bipolar cells in the retina?

Answer 41

ganglion

Question 42

What is the point where the optic nerve and blood vessels leave the eye?

Answer 42

the blind spot

Question 43

the blind spot

Answer 43

has no receptors

Question 44

What are ganglion cells in the fovea of humans and other primates?

Answer 44

midget ganglion cells

Question 45

by how much do rods out number cones in the retina?

Answer 45

20 to 1

Question 46

You sometimes find that you can see a faint star on a dark night better if you look slightly to the side of the star instead of straight at it. Why?

Answer 46

If you look slightly to the side, the light falls on an area of the retina with more rods and more convergence of input.

Question 47

If you found a species with a high ration of cones to rods in its retina, what would you predict about its way of life?

Answer 47

We should expect this species to be highly active during the day and seldom active at night.

Question 48

What are chemicals that release energy when struck by light?

Answer 48

photopigments

Question 49

we perceive color through the relative rates of response by three kinds of cones, each one maximally sensitive to a different set of wave lengths.

Answer 49

Trichromatic theory (Young-Helmholtz theory)

Question 50

the brain has a mechanism that perceives color on a continuum from red to green, another from yellow to blue, and another from white, to black. After you stare at one color in one location long enough, you fatigue that response and tend to swing to the opposite.

Answer 50

Opponent-processes theory.

Question 51

medium-wavelength cones respond most strongly to light that we perceive as green. long-wavelength cones responds most strongly to light that we perceive as yellow. According to the trichromatic theory, what causes us to perceive yellowish green.

Answer 51

We perceive yellowish green when the medium and long wavelength cones are about equally active but the short wavelength cones have very low activity. Each color experience corresponds to a particular ratio of firing by the three types of cones.

Question 52

According to the opponent-process theory, under what circumstance would you perceive a white object as blue?

Answer 52

If you stared at a bright yellow object for a minute or so then looked at a similar whit object, it would appear blue.

Question 53

The cortex compares information from various parts of the retina to determine the brightness and color for each area.

Answer 53

Retinex Theory

Question 54

When a television set is off, its screen appears gray. When you watch a program, parts of the screen appear black, even though more light is actually showing on the screen than when the set was off. What accounts for the black perception?

Answer 54

The black experience arises by contrast with the other brighter areas. The contrast occurs by comparison within the cerebral cortex, as in the retinex theory of color vision.

Question 55

500 nm light as blue and 550 light as yellow. Why should we nevertheless not call them “blue light” and “yellow light”?

Answer 55

Color perception depends not just on the wavelength of light from a given spot but also the light from surrounding areas. the context can change the color perception

Question 56

Why is color vision deficiency a better term than color blindness?

Answer 56

Very few people see the world entirely in black and white. The more common condition is difficulty discriminating red from green.

Question 57

Rods and cones of the retina make synapses with —- cells and —– cells.

Answer 57

1) horizontal
2) bipolar

Question 58

Where does the optic nerve start and where does it end?

Answer 58

It starts with the ganglion cells in the retina. Most of its axons go to the lateral geniculate nucleus of the thalamus’ some go to the hypothalamus and superior colliculus.

Question 59

The reduction of activity in one neuron by activity in neighboring neurons

Answer 59

Lateral inhibition

Question 60

When light strikes a receptor, does the receptor excite or inhibit the bipolar cells? What effect does it have on horizontal cells/ What effect does the horizontal cell have on bipolar cells

Answer 60

The receptor excites both the bipolar cells and the horizontal cell. The horizontal cell inhibits the same bipolar cell that was excited plus additional bipolar cells in the surround.

Question 61

If light strikes only one receptor, what is the net effect on the nearest bipolar cell that is directly connected to that receptor? What is the effect on bipolar cells to the sides? What causes that effect?

Answer 61

It produces more excitation than inhibition for the nearest bipolar cell. For surrounding bipolar cells, it produces only inhibition. The reason is that the receptor excites a horizontal cell, which inhibits all bipolar cells in the area.

Question 62

Explain why you see grayish diamonds at the crossroads among the black squares.

Answer 62

In the parts of your retina that look at the long white arms, each neuron is inhibited by white input on two of its sides. In the crossroads, each neuron is inhibited by input on all four sides. Therefore, the response in the crossroads is decreased compared to that in the arms.

Question 63

3 categories of primate ganglion cells

Answer 63

1) parvocelluar neurons
2) Magnocellular neurons
3) koniocellular

Question 64

Parvocellular

Answer 64

small celld bodies and small receptive fields, mostly in or near fovea. means small cell in Latin

Question 65

Magnocellular

Answer 65

larger cell bodies and receptive fields, evenly distributed in retina large celled in latin.

Question 66

koniocellular

Answer 66

small cell bodies but in retina means dust celled.

Question 67

As we progress from bipolar cells to ganglion cells to later cells in the visual system, are receptive fields ordinarily larger, smaller, or the same size? WHy?

Answer 67

They become larger because each cell’s receptive field is made by inputs converging at an earlier level.

Question 68

What are the differences between the magnocellular and parvocellular system?

Answer 68

Neurons of the parvocellular system have small cell bodies with small receptive fields are located mostly in and near the fovea, and are specialized for detailed and color vision. Neurons of the magnocellular system have large cell bodies with large receptive fields, are located in all parts of the retina, and are specialized for perception of large patterns and movements

Question 69

If you were in a darkened room and researchers wanted to read your mind just enough to know whether you were having visual fantasies’ what could they do?

Answer 69

Researchers could use fMRI, EEG or other recording methods to see whether activity increased in your primary visual cortex

Question 70

What is an example of an unconscious response to visual information.

Answer 70

In blindsight, someone can point toward an object or move the eyes toward the object, despite insisting that he or she sees nothing.

Question 71

has a receptive field with fixed excitatory and inhibitory zones.

Answer 71

simple cell

Question 72

in V1 and V2. does not respond to the exact location of stimulus. responds to pattern of light anywhere in large receptive field

Answer 72

complex cells

Question 73

has a strong inhibitory area at one end of its bar shaped receptive field.

Answer 73

End stopped

Question 74

How could a researcher determine whether a given neuron in the visual cortex is simple or complex?

Answer 74

First identity a stimulus, such as a horizontal line, that stimulates the cell. Then present the stimulus in several locations. If the cell responds strongly in only one location, it is a simple cell. If it responds in several locations it is complex

Question 75

What do cells within a column of the visual cortex have in common?

Answer 75

They respond best to lines in the same orientation. Also, they are similar in their preference for one eye or the other, or both equally.

Question 76

What is a feature detector?

Answer 76

It is a neuron that detects the presence of a particular aspect of an object, such as a shape or a direction of movement.

Question 77

What is the effect of closing one eye early in life? Both?

Answer 77

If one eye is closed during early development the cortex becomes unresponsive to it. If both eyes are closed, cortical cells remain somewhat responsive for several weeks and then gradually become sluggish and unselective in their responses.

Question 78

What causes astigmatism?

Answer 78

When the eye is not quite spherical

Question 79

An infant born with dense cataracts on both eyes and they are surgically removed years later, how well does the child see at first>

Answer 79

Child can see well enough to identity if objects are different but does not understand what the visual information means.

Question 80

What items does the brain have specialized areas for?

Answer 80

places, faces, and bodies including bodies in motion

Question 81

The ability to recognize faces correlates with the strength of connections between which brain areas?

Answer 81

occipital face area and fusiform gyrus

Question 82

Area V4 is important for color constancy. What is color constancy?

Answer 82

It is the ability to recognize the color of an object despite changes in the lighting.

Question 83

When you move your eyes, why does it not seem as if the world is moving?

Answer 83

Neurons in areas MT and MST respond strongly when an object moves relative to the background, and not when the object and background move in the same direction and speed.

Question 84

Under what circumstances does someone with an intact brain become motion blind, and what accounts for the motion blindness>

Answer 84

People become motion blind shortly before and during a saccade, because of suppressed activity in area MT.