senses IV Flashcards
Surfaces of objects do what with wavelengths?
Surfaces of objects absorb some wavelength and reflect others
What is doen with non-absorbed light?
reflected and picked up by eyes
How can reflectance of light be measured?
photospectrometer
Lens of the human eye absorbs UV and with increasing age……
also short wavelengths (violet, blue)
What are the proven dimensions of colour vision in animals?
dichromacy, trichromacy, tetrachromacy
Trichromats discriminate more colours than ….
dichromats
What is a trichromat?
seeing 3 colours
what is a dichromat?
seeing 2 colours
What are the three types of wavelength?
s, m and l-cones
How does colour vision defects affect each sex?
8% of males
0.5% of females
Which cone opsin genes are on the X chromosome?
M- and L-cone
which cone opsin gene is on chromosome 7?
S-cone
What is Protanomaly?
reduced sensitivity to red light
WHat is deuteranomaly?
reduced sensitivity to green light (MOST COMMON)
what is tritanomaly?
reduced sensitivity to blue light (RARE) – tritanopia: lacking the short-wavelength
Normal vision requires what?
at least one L, one M and one S pigment gene
What is trichromatic vision a result of?
gene duplication in primates (therefore close overlap of L- and M-cone spectral sensitivities).
Optimal to detect and distinguish ripe fruit.
What does colour vision result froM?
different types of opsin with different spectral sensitivities
What is a Spectrally opponent cell
Spectrally opponent cell: a visual receptor cell that has opposite firing responses to different regions of the spectrum
Who discovered the spectral composition of daylight?
Isaac Newton
What is colour constancy?
Ability to recognising colours under different illuminations
What is the Kanisza illusion?
solid triangle pointing upwards that is lighter than the background, which occludes an inverted triangle pointing downwards, and a set of black discs which are also occluded by the solid bright white triangle that points upwards. Surprisingly, none of these shapes are actually present in the figure.
What is sound?
pressure waves, movement of air particles set in motion by vibrating structure
Propagates in three dimensions, alternating compression and rarefaction of air, molecules move back and forth from regions of high pressure to low pressure.
What are measures of sound?
– frequency (reciprocal of wavelength, perceived as pitch) and amplitude (loudness), phase and waveform
What does movement fo the ossicles do?
pushes the oval window which moves the fluid inside the scala tympani
One the other end of the cochlea the round window bulges outward
What is the round window?
A membrane separating the cochlear duct from the middle-ear cavity.
What are the auditory receptors?
Inner (IHC) and outer (OHC) hair cells
What does bending of the stereocilia do?
Bending of the stereocilia (right) opens large, nonselective ion channels, allowing K+ and Ca2+ to enter the stereocilia. The resulting depolarization opens Ca2+ channels in the cell’s base, causing the release of neurotransmitter to excite afferent nerves (Hudspeth, 1992).
what does each superior olivary nuclei of the brainstem do?
receives inputs from both cochlear nuclei for first stage of binaural analysis of sound-source location.
Inferior colliculi are located in the dorsal midbrain.
Medial geniculate nuclei of the thalamus
What do the paths of the cochlear nucleus do?
One path from each cochlear nucleus goes to both superior olivary nuclei, so they both receive inputs from both right and left cochlear nuclei. This bilateral input is the first stage in the CNS at which binaural (two-ear) effects are processed;
What does the Jeffress model show?
Jeffress model of how the brain codes latency differences between sound heard by right and left ear by coincidence detection
