Neuro Exam Part 3 Visual System

Front 1

accomidation

Back 1

relfexation of the muscles surrounding the lens causing it to bend and refract light more

Front 2

scoptopic vision

Back 2

detecting gradations in numbers of photons (brightness) with little information about the energy of the photons (wavelength)

Front 3

additive colors

Back 3

cyan magenta and yellow are percepts of color created by the combination of neural activity through RGB channels - cones

Front 4

retinotopy

Back 4

retinal surface is mapped in a highly regular way such that adjacent points in the visual world are represented by adjacent synaptic influence in CNS

Front 5

photon

energy

Back 5

particle - contains mass - cannot occupy same place at same time

energy - not mass, propagation through space

Front 6

radient flux

Back 6

photon per unit time per area

intensity

Front 7

photon carrying capabilities

Back 7

all photons capable of carrying different amount of energy NOT intensity

Front 8

wavelength range

Back 8

400 nM = purple
700 nM = red

Front 9

modality of stimulus

Back 9

defined by the labeled line through which it is carried to the brain

Front 10

UV rankings

Back 10

UV C
UV B
UV A

Front 11

fovea

Back 11

sight of highest acuity in vision

smallest non-overlapping visual fields

Front 12

saccade

Back 12

motion of eyes constantly scanning

Front 13

peripheal vision

Back 13

light being directed to area proportionally as far from fovea

Front 14

only cell capable of AP in vision

Back 14

ganglion cell

Front 15

black melanin

Back 15

dark pigment which absorbs photons in back of eye

retracts at night

Front 16

duplex vision

Back 16

the seamless effort of paying attention to low vs high light energy at different levels

Front 17

influence of gAMP

Back 17

cGMP is the ligand for the ligand gated sodium channel in vision cells

thus in absence of cGMP, sodium channels are closed and the cell hyperpolarizes

Front 18

pigment

Back 18

any material that will absorb light

Front 19

transducin

Back 19

specialzed complex of g - protein and rhodopsin

Front 20

phototopic

Back 20

day time vision

Front 21

receptive field

Back 21

retinal surface that upon illumination enhances or inhibits the acitivity of the neuron

the area of the retina from which the activity of a neuron can be influenced by light

Front 22

end inhibition

Back 22

decrease in the response of a neuron as the length on an image increases

Front 23

three essential for clear vision

Back 23

- accomidation
-regulation of light
-convergence of the two eyes

Front 24

lateral geniculate nucleus

Back 24

relay station in the thalamus

six layers

end point of ganglion cells

Front 25

on and off regions

Back 25

ganglion cells have circular receptive fields with on off regions

on-depolarize of cell when light shone into center of receptive field

off - depolarize when light shone in annular illumination

Front 26

appropriate stimuli

Back 26

do not necessarilty initiate activity but rather modulate the resting discharge to either increase of decrease frequency

Front 27

size of receptive field

Back 27

receptive fields depend on location in retina, central have smaller receptive fields whereas in the peripheal has larger receptive fields

Front 28

M and P cells

Back 28

based on the projection of these neurons to the LGN and then to the cortex

Front 29

M cells

Back 29

magnocellular vision

project to large cells

-large receptive fields
-more sensitive to small differences in contrast and Movement

Front 30

P cells

Back 30

parvocellular division

project to the four smaller layers of cells

small receptive fields
high spatial resolution
sensitive to color and position

Front 31

cortical receptive fields

Back 31

neuronal firing rate is altered only when certain demands about position and form or stimulus are met

Front 32

simple cells

Back 32

for optimal activation need bar of light or certain width, fills central area completely, oriented in certain angle

illumination of surrounding area surpresses

Front 33

binocular vision

Back 33

both right and left receptive fields results in high frequency of firing

Front 34

requirments for both simple and complex - two

Back 34

- illumination of entire field is ineffective
-require specific axis orientation of the dark light boundry

Front 35

complex cells

Back 35

provide information about orientation without strict reference to position- on off zones not as strictly enforces with complex cells

Front 36

end inhibition

Back 36

due to lack of on off area, diffuse illumination outside field does not diminish response, thus not a conventional off area but rather end inhibtion

Front 37

ocular dominance columuns

Back 37

cortical cells with similar properties to be aggregated together in a vertical array

all neurons had the same receptive fields position and eye preference

CELLS RESPOND PREFERNTIALLY TO ONE EYE

Front 38

orientation columns

Back 38

arranged in a pinwheel

the field axis changes in a regular manner