Fourier Analysis, Synthesis, and CSF (M2)

Question 1

What does adding more and more harmonics to a Fourier synthesis get a closer approximation to?

Answer 1

the square wave

Question 2

Describe the visual system as a Fourier analyzer.

Answer 2

RGCs have varying receptive fields that act as more than one type of “spatially-tuned channel” that come together to make up the entire visual system

Question 3

When the stimulus is a low spatial frequency what happens in terms of the center-surround receptive field?

Answer 3

response is minimal because it is excited/inhibited about the same amount (different than blur)

Question 4

From the highest point in the CSF window of visibility, what causes a the loss of contrast sensitivity when the spatial frequency is decreasing?

Answer 4

loss due to lateral inhibition

Question 5

When the stimulus is at a “best” spatial frequency what happens in terms of the center-surround receptive field?

Answer 5

response is strong because it is excited by the center and inhibition is reduced in the surround

Question 6

When the stimulus is a high spatial frequency what happens in terms of the center-surround receptive field?

Answer 6

response is minimal because it is excited/inhibited about the same amount

Question 7

What can express every possible stimulus as a sum of sine waves?

Answer 7

Fourier synthesis

Question 8

What type of spatial frequency filters respond to the fine spatial structure of the world?

Answer 8

high

Question 9

What type of spatial frequencies does the Parasol/Magno pathway relay information?

Answer 9

low spatial frequencies

Question 10

What type of spatial frequency filters encode course luminance variations in the world (large objects and overall shape)?

Answer 10

low

Question 11

What does the CSF data of infants show? 1. Who else has results like these? 2

Answer 11

1. infants use their peripheral retinas for tasks

2. albinos

Question 12

From the highest point in the CSF window of visibility, what causes a the loss of contrast sensitivity when the spatial frequency is increasing?

Answer 12

loss due to blur

Question 13

What type of spatial frequencies does the Midget/Parvo pathway relay information?

Answer 13

all spatial frequencies, including high frequencies

Question 14

What can the sine waves that make up a stimulus be expressed as?

Answer 14

a spectrum in the spatial frequency domain

Question 15

What can analyze every possible stimulus into a series of component sine waves?

Answer 15

Fourier analysis

Question 16

How does a center-surround receptive field act as a filter on the spatial frequency spectrum of the stimulus?

Answer 16

detects information