Vision and Chemoreception - PSYC 2113

electromagnetic spectrum

range of frequencies of electromagnetic radiation often denoted at different wavelengths

cornea

clear outer surface of eye that bends light and is responsible for 80% of focusing images

lens

clear structure in the middle of eye that can be bent with ciliary muscles to change how light is focused on the eye

accomodation

act of focusing an image on the retina

retina

layer of cells at the back of the eye including photoreceptor cells, intermediate cells, and ganglion cells, where transduction takes place

ganglion cells

cells in retina that get info from intermediate cells and photoreceptor cells, axons of these cells make up the optic nerve

intermediate cells

cells in retina that transmit info from photoreceptor cells to ganglion cells, include bipolar, amacrine, and horizontal cells

rods

photoreceptor cells found in periphery of retina, responsible for scotopic vision

cones

photoreceptor cells found in fovea of retina, responsible for photopic vision

photopic vision

responsible for processing detail and color, works in high-intensity light

fovea

small portion of the center of the retina, highly populated with cones and is where we focus on an image

scotopic vision

responsible for movement and seeing in low light

cataracts

problem in vision where lens becomes cloudy, preventing light from passing through and getting to retina

myopia

nearsightedness, caused by an image that is focused at a point before the retina

hyperopia

farsightedness, caused by an image being focused past the retina

macular degeneration

retina begins to degenerate leading to loss of vision

retinitis pigmentosa

periphery of retina begins to degenerate causing complete blindness

transduction

conversion of physical stimulation to nerve impulses

cGMP

nucleotide that keeps Na+ and Ca++ channels open in membrane of photoreceptor cells, keeps neuron depolarized in dark

dark current

constant depolarized state of a photoreceptor cell when in the dark, caused by Na+ and Ca++ channels being kept open

photopigments

complex molecules in photoreceptor cell membranes made of opsin and retinal and change shape when struck by photon of light

opsin

large protein molecule connected to a retinal molecule

retinal

light-absorbing molecule

rhodopsin

photopigment in rods, light red in dark and yellow in light

transducin

messenger molecule activated when rhodopsin struck by light, sends message to deactivate cGMP closing ion channels

trichromatic theory

theory of color vision that assumes there are three types of cones which are sensitive to different wavelengths of light

opponent process theory

second theory of color vision that assumes cells in retina and thalamus send two different signals if excited or inhibited

lateral inhibition

process in retina where intermediate cells affect one another, highlighting areas where dark meets light and accentuating edges

receptive field

all cells in the visual system that influence another cell

center-surround

type of receptive field that looks like a donut, inner circle responds to light differently than outer circle

on-center ganglion cells

fires most when light hits the center of the receptive field and it is dark on the periphery

off-center ganglion cells

fires most when light hits the periphery of the receptive field and it is dark in the center

lateral geniculate nucleus

nucleus on the thalamus that gets info from ganglion cells of the retina, sends info to the primary visual cortex

retinotopic map

location of cells in LGN and primary visual cortex correspond to the map of the retina

parvocellular layers

layers 3, 4, 5, and 6 of LGN, get info from P-cells and process colors, shapes, and details

P-cells

ganglion cells that get info from fovea and sends info to parvocellular layers

magnocellular layers

layers 1 and 2 of LGN, gets info from M-cells and processes info about movement and low-intensity light

primary visual cortex

occipital lobe, builds up images through linear processing

simple cells

sensitive to lines of specific orientation on their receptive fields

complex cells

sensitive to lines of specific orientation moving in a specific direction

hypercomplex cells

sensitive to lengths and angles of lines

dorsal stream

“where” and “how” system for perception of motion and location

ventral stream

“what” system for object recognition and color perception

interior temporal lobe

cells that selectively respond to shapes

primary cells

respond to simple shapes

ex. squares, circles

elaborate cells

respond to complex shapes, textures, shapes with specific colors

face selective cells

respond to faces of specific people and orientation

prosopagnosia

inability to perceive faces

parallel processing

areas of brain involved with visual processing work together to use context and memory to facilitate visual info, can alter perception of what is physically sensed

olfactory

sense of smell

odorants

chemical signals in air that affect olfactory receptor neurons in nose

olfactory receptor neurons

bipolar neurons with cell bodies within olfactory epithelium and signal up into the olfactory bulb through olfactory nerve, affected by odorants

mitral cells

cells that get info from olfactory receptor neurons and then send their axons to several areas in the brain

glomeruli

round structures in olfactory bulb where connections are formed between the terminal end of the olfactory receptor neurons and dendrites from the mitral cells

HeroRATS

rats trained by the organization APOPO to detect mines, explosives, and tuberculosis

gustatory

sense of taste

tastants

chemical molecules in food that dissolve in saliva and affect chemoreceptors on tongue initiating flavor perception

taste papillae

bumps on tongue

taste receptor cells

in papillae, where transduction takes place

supertaster

more papillae, more sensitive to bitter flavors

artificial retina

electronic devices that are placed beneath the retina to restore vision in people with retinal diseases

smart contact lenses

advanced contact lenses being developed to take pictures, record videos, or monitor biomarkers in the eye or tears

hearing aids

devices used for those who are hearing impaired to amplify and manipulate sounds

cochlear implants

devices surgically implanted into the cochlear that transduce sound into stimulation at specific areas on the basilar membrane