1what elements does the visual system contain ?
1. basal ( color , lines , angles )
2. higher order ( what and where)
3. associations
2what is the route of visual system?
stimulus > organ receptor > transduction > coding > projection to cortex >higher order processing
3how can a stimulus differ?
1. color ( hue ) intensity
2. saturation ( colour mixing)
3. intensity
4what are the components of the eye ?
conjunctiva ( merges with inside of eyes)
cornea
sclera
iris
pupil
lense
vitreous humor
fovea
optic nerve
blind spot
second cranial nerve
5what is the role of the pupil ?
contracts or relaxes
6what is the role of the iris ?
color of the eye
7what is the role of the lense ?
connected to muscles to contract or relax in order to project the light to the retina : accommodation
8what is the rol eof the vitreous humor?
fills the space between the lens and the retina of the eyeball making the eys round
9what is the role of fovea ?
specialised with seeing the colors presented sharpest color and vision
10what is the role of the optic nerve ?
sends the information to the visual thalamus
11what is the blind spot ?
no space for photoreceptors : cannot see that part (brain fills in the part )
12what are photoreceptors ?
**the cells in the retina that respond to light**
13where are photoreceptors placed ?
in the retina
14how does light get to the photoreceptors?
trough the bipolar cell
15what is lamina ?
the lamina are shelves where photochemical are laying
16what is the route when light comes in ?
light > bipolar cells > photoreceptors
17what is the route when the informationg goes out ?
lamina > electrical charges > cones and rods > bipolar cells > ganglion celss > optic nerve > brain
18what are ganglion cells ?
Ganglion cells collect information about the visual world from bipolar cells
19what is the receptive fild ?
light that comes fromt the right side is recognised by the left side of the eyes
20how are ganglion cells implicated in receptive fields ?
in order for a region to be seen a increase in firing frequency of the ganglion neuron needs to take place
21what is the transduction process ?
the coding of hue
22what do lamella contain in order to see colour ?
photo pigment
23what photo pigments do lamella conatin ?
opsin and retial
24what is opsine ?
a protein
25what is retinal ?
a lipid from vitamin A
26which photo pigment is present at all times ?
opsin is different each time while retinal is the same at all times
27what is the function of cones ?
see in the day and colour
28what is the combination in the cones ?
cyanolabe + retinal ( blue )
chlorolabe + retinal (green )
erythrolabe + retinal (red)
29what is the role of rods ?
we use to see at night and black and white
30what is the combination within the rods ?
opsin + retinal : rhodopsine
31why do we use rods at night more ?
rodopsine splits very easily
32how do we code light intesity ?
number of action potential per time unit : frequency
on and off cells
33what are on cells ?
activate when light hits center of receptive field
inhibited when light falls outside the center
34what are off cells ?
inhibited when light in center and activate when light outside center
35what is the rebound effect ?
when visual cells have been stimulated / inhibited for a longer time they will exhibit a " rebound effect " and fire at slower / faster. rate then normal
36what is an exmaple of the rebound effect ?
look for a long time at black regions when taken away that region will become much more bright and vice versa
*afterimage light. becomes dark and dark becomes light if you
37what is one main role of onn and off cells ?
edge detection
38how do we detect edges ?
when part of the onn cells is inhibited a bit more and other part inhibited less there is a perception that a lighter area exists ( in reality it is not lighter )
39what is trichonomatic coding ?
the coding of colour based on the three types of cones
40what types of cones are there ?
1. red
2. green
3. blue
41what is the opponent precessing coding ?
the pair of red green and blue yellow ganglion cells
depending on the inhibition / agtivation of these cells we get specific colours
42which cells are responsable for the oponent processing coding?
the retinal ganglion cells
43which colours are important for the oponent prcessing ?
red
blue
green
**yellow**
44when can we see green and red ?
red : when the redgreen ganglion cell is activated
green : when the redgreen ganglion cell is inhibited
45when can we see blue and yellow?
yellow : when the blueyellow is activated
blue : when the blueyellow is inhibited
46when can we see a rebound effect in the oppnent colours coding ?
when ganglion cells are stimulated or inhibited for a long time they will exhibit a " rebound effect " and they will fire at a lower/faster rate than normal
47what are the basic visual characteristics that projection to cortex sees ?
orientation
movement
location and depth
48how can we detect orientation ?
we have specific neurons to see specific orientation ( some neurons respond to speific orientation : vertical )
49how can we reason orientation detection ?
we can see specific neurons that fire in the brain when we look at lines in a specific direction
50what are complex cells ?
complex cells combine information from simple cells
51what are simple cells ?
on and off cells
52how can we see orintation of whole lines ?
simple cells combine information form LGN cells
53what are LGN cells ?
the cells in the thalamus that are used for vision aka Lateral Geniculate Nucleus ( LGN cells )
54how can we detect movement ?
simple cells will fire consecutively in case a movement of vertical line
complex cell detects movement
55how can we detect location ?
retinotopic organisation : signific regions of the visual field project to specific parts of the thalamus and visual cortex
each scene is projected to a specific location in the brian
56what is retinotropic organisation ?
**the spatial organization of the neuronal responses to visual stimuli**
57how can we detect depth ?
from binocular disparity : difference in image location of an object seen by the left and right eye
58what is one exmaple of the use of binocular disperity ?
3D movies
59what is the higher order porcessing?
the what and where
60what is the "what " stream ?
the ventral stream
61what is the " where " stream ?
the dorsal stream
62what role does the dorsal steam have ?
spatial awareness
movement perception
visuomotor coordination tracking
63what role does the ventral stream have?
colors
shapes
patterns ( faces )
64what are th epossible "what stream" damages ?
1. V4
2. V8
3. appreciative agnosia
4. prosopagnosia
65what does damage to area V4 imply ?
impaired color consistency : corrects to different background lighting conditions
66what does damage to area V8 imply ?
results in impaired color vision and color imaging and color memory
67what is appreciative agnosia ?
problem with recognising objects and combining information of each object into a whole
68what does prosopagnosia mean?
problem with face recognizing ; you can detect the characteristics of a person but cannot link to who they are
69what are the " where and how " possible damages ?
1. lateral (LIP) and ventral (VIP)
2. VIP and medial (MIP)
3. anterior (AIP)
4. caudal (CIP)
5. MT and V5
70what is the LIP nad VIP damage cause ?
visual attention and eye movement damage
71what does the VIP and MIP damage cause ?
visual control of grasping and pointing
72what does the AIP damage cause ?
grasping and manipulation with hands
73what does the CIP damage do ?
depth perception
74what do leasions in medial temporal lobe cause ( MT and V5) ?
results in problems with perception of movement : akinetopsia
75what do leasion in the MST cause ?
optic flow (perception of heading )damage