Chapter 6: Vision + Chemoreception

light

a wave and photons (small packets of energy)

cornea

outer translucent covering of the eye

lens

bends to accommodate light on the retina

retina

ganglion cells (hit first by light)

intermediate cells + photoreceptor cells

photopic vision

!! details, bright light, color vision

cones = photoreceptors

fovea

fovea

center of retina packed with/ cones

scotopic vision

!! movement, low light, shapes

rods = photoreceptors

periphery of retina

transduction

conversion of physical stimulation to nerve impulse

trichromatic theory

3 cones in retina; the have their own photopigments that are sensitive to differ. wave lengths

blue = short

green =medium

red= long

opponent process theory

2nd theory of color vison

retina & thalamus sending 2 differ signals if excited/inhibited

ganglion cells in retina + cells in thalamus send differ color signals depending on if they’re excited/inhibited

receptive field

intermediate cells & ganglion cells get info from field of photoreceptor cells

is round in center-surround configuration

lateral inhibition

lateral inhibition

dark meets light due to intermediate cells affecting one another = accentuating edges

receptive fields

ganglion cells gather info from receptive fields gives it to cortex to create shapes + edges

on-center ganglion cells

fires when light hits the center of receptive field & dark on periphery

off center ganglion cells

fires when light hist periphery of receptive field & is dark in center

visual pathway

axons from ganglion cells make up optic nerve

goes from retina to temporal as ipsalteral

goes from nasal retina cross at optic chasm to contralateral side of eye

lateral geniculate nucleus of thalamus

part of optic nerve tract

retinotopic

map of retina

parvocelluar layers of LGN

photooptic vsision

receives in of from. P Cells

P cells

ganglion cells with receptive fields in the fovea

magnocellular layer of LGN

scotopic vision

receives info from M cells

M cells

ganglion cells with receptive field in periphery of retina

primary visual cortex

in occipital lobe

AKA straite cortex or V1; is retinotopic

has more neurons than the thalamus

builds up images though linear process: simple cells, complex cells hypercomplex cells

simple cells

sensitive to lines in specific orientation of receptive fields

complex cells

sensitive to lines of specific orientation moving in specific direction