Vision (Chapter 7)

rods and cones

receptors in the retina

iris

connected to muscle and contracts/releases and allows more/less pupil to be seen - changes the amount of light that comes in

ciliary muscles

pull the lens tighter (helps to look far away and releases to look close up)

lens

behind the pupil, becomes more rigid as we get older, inverts info - brain flips it back when we receive it

sclera and choroid

white part of the eye, rigid protein membrane, helps form the shape of the eye

retina

all neurons in the yeeball

fovea

central focus region and color vision region

optic nerve

ganglion cells leave the eyeball in a tight bundle, blood flows in and out of same space

heminasal

anything that happens on nose side

hemitemperal

anything on the temple side

myopia

nearsightedness; eyeball slightly too long and focal point of light falls short of the retina

hyperopia

farsightedness; eyeball slightly too short and focal point of light falls too long of the retina

presbyopia

age-related farsightedness due to lens rigidity

rods

key role in night vision and peripheral vision; more numerous than cones; sensitive to low light, one type of pigment only

cones

key role in daylight vision and color vision; responsive to bright light, located in fovea only, 3 types of pigment

photopigment

light sensitive chemicals in rods and cones that initiate transduction of light waves into electrical neural impulses (rhodospin)

blind spot

point where optic nerve exits, no rods/cones present

horizontal cells

interconnects adjacent photoreceptors and outer processes of bipolar cells

amarcine cells

connects adjacent ganglion cells and inner processes of bipolar cells

ganglion cells

axons in the optic nerve and also the reason for the blind spot

optic chiasm

junction of the optic nerve from each eye; axons from the nasal halves cross over to the opposite sides of brain

LGN (lateral geniculate nucleus)

only stop off point for neurons in the thalamus

geniculostriate system

primary visual cortex in the occipital

tectopulvinar system

thalamus, on to parietal/temporal visual areas

dorsal stream

visual spatial perception

ventral stream

visual pattern recognition

scotoma

blind in a specific area of the receptive field

perimetry

mapping the extent of a patient's scotoma

visual agnosia

patient can't recognize objects unless touching them (damage in temporal cortex)

prosopagnosia

inability to recognize faces and complex objects with curved surfaces (FFA lesion)

akinetopsia

loss of motion perception, unable to judge direction/speed of moving objects (large bilateral lesions)

motion blindness

likely caused by damage in area MT

subtractive color mixing

mixing occurs w/in stimulus itself

additive color mixing

mixing different light wavelengths

short wavelength

blue

middle wavelength

green

long wavelength

red