colour vision and hearing

Question 1

which pathways process colour?

Answer 1

parvocellular

Question 2

what does the light stimulus reaching the photoreceptors differ based on?

Answer 2

differ depending on the object surface and the transmitting media

we see the non-absorbed light

Question 3

what colours do the human eye absorb?

Answer 3

absorbs UV and short wavelengths

Question 4

difference between trichromats and dichromats?

Answer 4

trichromats (blue, red and green) discriminate more colours than dichromats (blue and red)

Question 5

which colours do specific cones detect?

Answer 5

s cones - short wavelength - blue

m cones - medium wavelength - green

L cones - long wavelength - red

Question 6

which cones are coded in which chromosomes?

explanation for colour blindness?

how many of them do you need?

Answer 6

S cone opsin gene on chromosome 7

m and L cone opsin genes on X chromosome (males more likely to be colour blind as only have 1 X chromosome)

need 1 of each gene

Question 7

difference between severe and mild colour deficiency?

Answer 7

mild: one cone opsin mutated
severe: only 2/3 cone opsins expressed in retina

Question 8

what are protanomaly, deuteranomaly and tritanomaly?

Answer 8

prota - missing L cone so reduced sensitivity to red light

deutera - missing M cone

trita - missing s cone (rare as on chromosome 7 not X)

Question 9

what is meant by polymorphic monkeys?

why is this?

Answer 9

coexisting tri (3 wavelengths) and dichromats (2 wavelengths not M cone)

evolution of trichromatic vision to detect fruits (green and yellow) or detecting social cues

Question 10

what do different opsins differ in?

Answer 10

have different spectral sensitivities for wavelength (peak at different points)

Question 11

what is a spectrally opponent cell?

and an example?

Answer 11

visual receptor cell that has opposite firing responses to different regions of the spectrum

e.g ganglion cell

Question 12

how are ganglion cell affected by wavelength?

what does this make it?

Answer 12

excited and fire in response to some wavelengths

inhibited and don’t fire by other wavelengths

• this makes it a spectrally opponent cell

Question 13

what is the achromatic pathway?

Answer 13

brightness

L (red) and M (green)

Question 14

who and when did someone discover the spectral composition of daylight?

Answer 14

newton

1672

Question 15

what is perceived as white light?

Answer 15

mixture of green, red and blue light

M, L and S

Question 16

what is colour constancy?

Answer 16

ability to recognise colours under different illusions

e.g dusk and dawn compensation by visual system

Question 17

what is sound?

Answer 17

pressure waves
movement of air particles set in motion by vibrating structure

3 dimensions

Question 18

what are the measures of sound?

Answer 18

frequency - pitch

amplitude - loudness

Question 19

which location do sound waves hit?

what does it not do?

Answer 19

the tympanum

doesn’t preserve spatial arrangement of sound

Question 20

how are hair cells arranged in the cochlea?

what is the cochlea?

Answer 20

tonotopic arrangement

inner ear canals

Question 21

what are the 2 auditory receptors?

Answer 21

inner (IHC) - sound perception

outer hair cells (OHC) - change length to fine tune organ of Corti

Question 22

describe the auditory nerve?

Answer 22

axons spiking auditory interneurons that innervate the hair cells

Question 23

what is the role of stereocilia on auditory receptors?

Answer 23

stiff hairs which stretch open ion channels

Question 24

how is sound localised?

Answer 24

sound source location computed from the differences in delay and intensity between the 2 ears

Question 25

what does Jeffress model show?

Answer 25

how the brain codes latency differences between sound heard by right and left ear by coincidence detection