week 3

Question 1

Max cone density ~ ?

range of cone densities?

Answer 1

Max cone density ~ 160,000

~125-200,00

Question 2

which is associated with a sustained temporal response: parvo or magno GCs?
transient?

Answer 2

sustained=parvo

transient=magno

Question 3

parvo GCs are sensitive to a max of motion at __deg/sec and peak motion sensitivity at __ deg/sec

Answer 3

max: 10deg/sec
peak: 2-5 deg/sec

Question 4

magno GCs are sensitive to a max of motion at __deg/sec and peak motion sensitivity at __ deg/sec

Answer 4

max: 300 deg/sec
peak: 30 deg/sec

Question 5

some konio cells respond best at 10-15deg/sec which is optimal for what 2 purposes?

Answer 5

1) OKN

2) predictive calculation of velocity used in tracking

Question 6

what is linear summation? which cells exhibit it, magno or parvo GCs?

Answer 6

when a border for a an area between light and dark is centered over a receptor field then reversed, cell response should remain constant;
parvo cells: linear summation
magno cells: NONlinear summation (may provide texture info)

Question 7

troxler effect:

Answer 7

If you fixate on a particular point for even a short period of time, an unchanging stimulus away from the fixation point will fade away and disappear
*small fixational eye movements are not enough to stimulate large receptive fields of periphery so it disappears

Question 8

in absence of stimuli, GCs have an AP firing rate of:

for an on center off surround, what happens to AP rate if light illuminates entire cell?

Answer 8

30 AP/sec

-only a very slight increase in AP

Question 9

What is fourier transformation?

Answer 9

Any waveform and theoretically any image can be generated or completely described by some particular set of sine waves

Question 10

Nyquist limit:

Answer 10

60cpd=20/10 VA

Question 11

what is a Moire pattern?

Answer 11

If a very high frequency grating is projected onto the retina, you can see a Moire pattern between your cones and the gratings
“cone mosaic aliasing”

Question 12

CSF loss at low frequencies is due to _____

Answer 12

lateral inhibition

Question 13

CSF loss at high frequencies is due to what factors?

Answer 13

optics, cone density, receptive field sensitivity and size

Question 14

minimum requirements of # of photopigments and rceeptors for color vision?

Answer 14

At least 2 pigments with 2 diff receptor types for comparison

Question 15

There are 3 photoreceptors – each with a diff spectral sensitivity functions that peak at what 3 wavelengths?

Answer 15

3 peaks are at 570, 540 or 440 nm

Question 16

what is the app distribution of L M and S cones?

Answer 16

70%=L cones
25%=M cones
5% =S cones

Question 17

Young-Helmoltz Trichromatic Theory of Color is correct at what level?

Answer 17

cone level

Question 18

T/F: S cones do not contribute to photopic spectral sensitivity

Answer 18

true

Question 19

are S cones found in the fovea?

Answer 19

NO

Question 20

what clinical test can you use to measure S cone function?

Answer 20

HRR 4 (NOT Ishihara)

Question 21

in optically perfect eyes, vision would be limited by:

Answer 21

cone density