9.4

Question 1

What do RGCs respond to in their receptive field? Why?

Answer 1

They respond to the presence or absence of light. They are too small to detect shape.

Question 2

What shape is an RGC’s receptive field?

Answer 2

Concentric circle (like a donut!)

Question 3

What excites an on-center cell? What inhibits it?

Answer 3

Excited when light falls directly on the center. Inhibited when light falls on the surround.

Question 4

What happens when light shines on an entire on-center cell?

Answer 4

It becomes weakly excited.

Question 5

What excites of off-center cell? What inhibits it?

Answer 5

Excited when light falls on the surround. Inhibited when light falls on the center.

Question 6

What happens when a light shines on the entire receptive field of an off-center cell?

Answer 6

It becomes weakly inhibited.

Question 7

What is luminance contrast?

Answer 7

Amount of light an object reflects relative to its surroundings.
How RGCs can give the brain information about shape.

Question 8

What kind of information about shapes are RGCs sending the brain (because of luminance contrast)?

Answer 8

They are sending signals about edges. Edges form shapes

Question 9

What are V1 cells also known as (when talking about processing shapes)?

Answer 9

Orientation detectors

Question 10

What are orientation detectors with rectangular shape called?

Answer 10

Simple cells

Question 11

What are the three types of orientation detectors in V1?

Answer 11

Simple cells, complex cells, hypercomplex cells

Question 12

What are complex cells?

Answer 12

Orientation detectors that are maximally excited by bars of light moving in a particular direction through the receptive field

Question 13

What are hypercomplex cells?

Answer 13

Orientation detectors that are maximally responsive to moving bars with a strong inhibitory area at one end of the receptive field

Question 14

What shape is a complex cell and hypercomplex cell’s receptive field?

Answer 14

Circular (not concentric like RGCs)

Question 15

How are neurons organized in the cortical structure in V1?

Answer 15

Organized into functional columns with a vertical connectivity pattern

Question 16

What is selective orientation in V1?

Answer 16

V1 neurons respond best to bars or edges in the orientation that matches their input alignment

Question 17

What is an ocular dominance column?

Answer 17

A functional column in the visual cortex that is maximally responsive to information coming from one eye

Question 18

What layer of V1 do inputs arrive to? How does it connect to other layers (orientation)

Answer 18

Inputs arrive in layer IV and connect vertically with other layers.

Question 19

What excites neurons in the temporal lobe region TE?

Answer 19

Complex visual stimuli (e.g faces)
Can be very specific in what they respond to

Question 20

What is stimulus equivalence?

Answer 20

Recognizing an object as remaining the same despite being viewed from different orientations

Question 21

How are stimulus preferences different in V1 vs. the TE region of the temporal lobe?

Answer 21

V1 neurons are not modified by experience whereas TE neurons are.

Question 22

What is trichromatic theory?

Answer 22

Explanation of color vision based on the coding of three primary colors: red, green, and blue

Question 23

What is subtractive color mixing?

Answer 23

Mixing red blue and yellow to make all the colors. Mixing the three makes black. What painters use.

Question 24

What is additive color mixing.

Answer 24

Reflects light waves we see as red, blue, and green. When all visible wavelengths are reflected, we see white.

Question 25

What is protanopia?

Answer 25

The lack of red cones. Inability to see red

Question 26

What is deuteranopia?

Answer 26

The lack of green cones.

Question 27

What is tritanopia?

Answer 27

The lack of blue cones

Question 28

Where is color vision processed in primates?

Answer 28

V1 and V4

Question 29

What is the opponent process?

Answer 29

Explanation of color vision that emphasizes the importance of the apparently opposing color pairs: red vs green and blue vs yellow.

Question 30

According to the opponent process, if an RGC is excited by a blue wavelength, what would it be inhibited by?

Answer 30

Yellow wavelengths

Question 31

What is color constancy?

Answer 31

The property of perception whereby colors appear to remain the same relative to one another despite changes in light

Question 32

What area of the brain is speculated to be important for color constancy?

Answer 32

V4

Question 33

What is the role of neurons in the posterior parietal cortex (dorsal stream)?

Answer 33

Processing visual information for action

Question 34

Neurons in the primary visual cortex respond to properties of shapes, especially to ______ oriented in a certain direction

Answer 34

Bars of light

Question 35

Recognition of complex visual stimuli such as faces is completed in the _______ lobe

Answer 35

Temporal (Inferotemporal cortex as stated in slides)

Question 36

The idea that the color we see is determined by the relative responses of the three cone types in the retina is called _________

Answer 36

Trichromatic Theory

Question 37

RGCs mediate color vision by _________ processes

Answer 37

Opponent

Question 38

Describe the opponent process in the retinal ganglion cells

Answer 38

RGCs are excited by one wavelength of light and inhibited by another, producing two pairs of what seem to be color opposites - red vs green and blue vs yellow