L4 - Animal Senses and the Brain I (exteroception) Flashcards
What are key factors about SENSORY ORGANS?
- They are structures that detect specific sensory stimuli within one ‘modality’ (a category of sensation such as vision, hearing/audition, smell/olfaction, ect)
- They contain modality- specific sensory cells, which can vary in sensitivity, and in the quality of stimulus that most stimulates them (e.g. frequency of light or sound; the chemicals present in the food, ect.)
- Their sizes and structures vary, affecing their function
Label indcated arrows
- retina
- optic nerve
- lens
- iris
- retractor lentis muscle
What is the OPTIC TECTUM called in mammals?
the visual/superior colliculus
True or False?
The visual corticeis are CONTRALATERAL
True
Label this ROD CELL
- Membrane sheles lined with rhodopsin or colour pigment
- Outer segment
- Mitochondria
- Inner segment
- Outer limiting membrane
- Nucleus
- Synaptic body
Lebel this CONE CELL
- Invaginations of cell membranes that form a stack of membranous disks where photopigments exist as transmembrane proteins
- Outer segment
- Connecting cilium
- Mitochondria
- Inner segment
- Nucleus
- synaptic terminal that forms a synapse with a neuron
How many types of cone cells are there is primate (including humans) retinas and what wavelength do they peak at?
- There are 3 types of cone cells in the retina; making primates “trichromatic”
- peak at 450 (blue), 540 (green), 580 (red)
What kinds of animals are DICHROMATIC?
- Carnivores: Dogs, foxes, mink, cats, ect.
- Ungulates: Cattle, sheep, goats
- Rodents
What colours/ wavelength do most CARNIVORES see?
To us
- purplish/blue (peak 440nm)
- yellowish/green (peak 555nm)
Are dogs red-green colour blind?
Yes
Are cats red-green colour blind?
Unclear
What colour/wavelength do most UNULATES see?
To us
- Peak at 440-455 and 536-555nm
- despite this, NOT red-green colour blind: instead poor at distinguishing greens from blues and violets
What colours/wavelengths do most RODENTS see in?
- ultraviolet (359nm) & yellow-green (510nm)
- they cannot see red
- therefore redlights are used in labs to imitate darkness for the rodents.
How many different types of cone cells are in birds?
Birds have 4 different types of cone cells
This make birds tetrachromatic
Bird feathers are UV absorbant/reflective
True or False?
True
Some birds have patterns that we humans cannot see
What does visual ACUITY depend on?
Acuity depends on cone cells plus quality of the lens
Facts on ACUITY in DOGS
- dogs have more rod cells plus a tapetum lucidum
- see less well in the daytime compared to humans
- better night sight than us
Facts on ACUITY in BIRDS
- birds have far BETTER visual acuity that humans
- House sparrow: 400 000 receptors per mm2 of retina
- Buzzard: 1 000 000 receptors per mm2 of retina
- Humans: 200 000 receptors per mm2 of retina
What types of eyes collect more photon?
Large pupil and/or large retinas receive more photons
What is the ‘TAPETUM LUCIDUM’?
The layer reflects photons so not absorbed before reaching retina
- evolved seperatly in different groups
- carnivores and onmivors have reflective layers made from different stuff
- light reflective crystals (e.g. carnivores)
- layer of extracellular fibres (e.g. ungulates)
Label
What does SACCADES mean?
rapid, ballistic movements of the eyes that abruptly change the point of fixation.
What is the function of the VISUAL CORTICES?
- processing visual data: they clean them up and makes calculations
- merge info from both eyes
- “remove” your nose
- cancel out extraneous body and eye movement
- speed of moving objects
- small object or far object?
- different object or just different angle
What is OBJECT INVARIANCE’
a function of the visual cortex- allows us to recognize that different images from different viewing angles all represent the same thing
