colour vision and hearing Flashcards
which pathways process colour?
parvocellular
what does the light stimulus reaching the photoreceptors differ based on?
differ depending on the object surface and the transmitting media
we see the non-absorbed light
what colours do the human eye absorb?
absorbs UV and short wavelengths
difference between trichromats and dichromats?
trichromats (blue, red and green) discriminate more colours than dichromats (blue and red)
which colours do specific cones detect?
s cones - short wavelength - blue
m cones - medium wavelength - green
L cones - long wavelength - red
which cones are coded in which chromosomes?
explanation for colour blindness?
how many of them do you need?
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
difference between severe and mild colour deficiency?
mild: one cone opsin mutated
severe: only 2/3 cone opsins expressed in retina
what are protanomaly, deuteranomaly and tritanomaly?
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)
what is meant by polymorphic monkeys?
why is this?
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
what do different opsins differ in?
have different spectral sensitivities for wavelength (peak at different points)
what is a spectrally opponent cell?
and an example?
visual receptor cell that has opposite firing responses to different regions of the spectrum
e.g ganglion cell
how are ganglion cell affected by wavelength?
what does this make it?
excited and fire in response to some wavelengths
inhibited and don’t fire by other wavelengths
- this makes it a spectrally opponent cell
what is the achromatic pathway?
brightness
L (red) and M (green)
who and when did someone discover the spectral composition of daylight?
newton
1672
what is perceived as white light?
mixture of green, red and blue light
M, L and S
what is colour constancy?
ability to recognise colours under different illusions
e.g dusk and dawn compensation by visual system
what is sound?
pressure waves
movement of air particles set in motion by vibrating structure
3 dimensions
what are the measures of sound?
frequency - pitch
amplitude - loudness
which location do sound waves hit?
what does it not do?
the tympanum
doesn’t preserve spatial arrangement of sound
how are hair cells arranged in the cochlea?
what is the cochlea?
tonotopic arrangement
inner ear canals
what are the 2 auditory receptors?
inner (IHC) - sound perception
outer hair cells (OHC) - change length to fine tune organ of Corti
describe the auditory nerve?
axons spiking auditory interneurons that innervate the hair cells
what is the role of stereocilia on auditory receptors?
stiff hairs which stretch open ion channels
how is sound localised?
sound source location computed from the differences in delay and intensity between the 2 ears
what does Jeffress model show?
how the brain codes latency differences between sound heard by right and left ear by coincidence detection
