cgs 2301 - vision

five senses

vision, audition, touch, taste, smell

phantom pain phenomenon

painful sensations that seem to originate in a limb that is no longer present

• burning, aching, throbbing, crushing, and/or shooting pain

mirror box treatment

shows how important vision is!

• patient sits with a mirror in between so healthy limb is reflected in the mirror

• moves healthy limb while looking at the mirror

• brain is tricked into thinking amputated limb is moving normally too

cornea

• round, clear outer structure that covers eye

• initial light refraction

pupil

• lets light in

• smaller diameter in bright light

• larger diameter in darkness

iris

• dilates/constricts the pupil

• eye color

lens

• behind iris

• changes shape to change focal distance

• absorbs light and bends it to converge to a single point

• fine tuns focusing light after cornea

emmetropia

perfect vision (20/20)

myopia

• nearsightedness → close objects are clear, far objects are blurry

• light focuses in front of retina

myopia w/ correction

fixes vision so light focuses on retina

hyperopia

• farsightedness → close objects are blurry, far objects are clear

• light focuses behind retina

retina

contains photoreceptors (rods and cones) for light transduction

photoreceptors

• rods and cones

• they don’t see color, rather they sense light

rods

• more sensitive

• better in low light

• better with motion

• black and white vision

• located in periphery of retina

cones

• color vision

• high acuity/detail

• located in center of retina (can remember bc cones and center both start with c)

fovea

• center of visual field

• highest concentration of cones

blind spot

small area where optic nerve connects, so there’s a “hole” in vision that the brain compensates w info from the other eye

eye floaters

small spots or specks that appear to float in visual field

optic chiasm

visual field info crosses over to contralateral hemisphere

V1

V2

V3

V4

V5

retinotropic mapping

receptive fields

parvoceullular cells

koniocellular cells

magnocellular cells

• large receptive fields

• sensitive to motion, large objects, and spatial orientation

• projects to dorsal stream