More in-depth on visual processing Part 1

Question 1

what is the name of the visual field that has overlapped information from both visual fields and helps with the perception of depth?

Answer 1

Binocular visual field

Question 2

what is the name of the dysfunction of one side of the visual field?

Answer 2

hemianopia

Question 3

what is the brain part that supports the V1 and it’s usage

Answer 3

Calcarine Fissure. divides the upper and lower visual field by identifying the light from the upper and lower field
Upper calcarine fissure = light from the lower source (vice versa)

Question 4

Describe the characteristics of retinotopic organisation

Answer 4

-> Lights with near location = stimulates the similar area of the retina = stimulates similar area of the V1.
-> Cortical magnification: more cortical cells are dedicated on the information from fovea than the peripheral.
-> Light from the upper visual field stimulates the lower bank of the V1.

Question 5

Describe the functional organisation of the V1

Answer 5

6 layers
2-3: koniocellular layer: layer 3 also contributes output to other visual areas.
4: magnocellular layer
Inputs from layer 2-4 are from the lateral geniculate nucleus (LGN)
5-6: Parvocellular layer
blobs: inside the V1 that process different information from cones (i.e., colours)

Question 6

Areas related to vision

Answer 6

V1 = primary visual cortex
V4 = perception of colour
V5/MT = perception of motion
Inferior Temporal Cortex = perception of complex objects and faces

Dorsal stream = responsible for the perception of movement of visual information
Ventral stream = responsible for depicting the world from visual input

Question 7

Components of the brain that processes motion

Answer 7

-> true that the LGN and the V1 process motions in some extent. However, not sophisticated enough to process all motions that we see
-> MT and MST do.

Medial Temporal Area (MT):
-> neurons in the area perceive and process directive motions
-> neurons also show adaptation -> motion after effects
-> akinetopsia = dysfunction of the MT (cannot perceive motion. However, biological movement) still observed -> evidence that MT is not responsible for biological movement

Medial Superior Temporal Area (MST):
-> responsible for optic flow (motions caused by the movement of the body)
-> responsible for complex motions (e.g., spiral)
-> responsible for biological movements (e.g., movements of dots that look like a person)

Question 8

Explain colour perception

Answer 8

colour perception relies on the signals from the RGCs.
the RGCs themselves conceive colours in a similar fashion as the on-off cell
> red-on-green-off cell
> green-on-red-off cell
> yellow-on-blue-off cell
> blue-off-yellow-on cell

If
red signals is transmitted from the R cones > signals will exhibit the red-on-green-off RGC > show red
green signals is transmitted from the G cones > signals will inhibit the red-on-green-off > show green
blue signals send from the B cones > signals will inhibit the yellow-on-blue-off cones > show blue
yellow signals send from R+G cones > the R+G signals will exhibit the yellow-on-blue-off cones + the effects of the red-on-green-off cells will be neutralised > show yellow

Question 9

What’s after the RGCs perception of colour and achromatopsia

Answer 9

The signals will reach the the CO blobs in the V1 through the LGN
The send the signals to the V4 to perceive colour
Know that V4 is essential for colour perception as the damage of the V4 leads to Achromatopsia, which is the lost of ability to perceive colour, just seeing grey

Achromatopsia is different from retinal dysfunction (deuteranopia and Protanopia)
Only lost colour of half of the visual field vs entire field
seeing only grey vs just lack of colours related to green cones and red cones

Question 10

What layers are taking information from the opposite eye and which layers are taking information from the

Answer 10

1,4,6 = opposite eye
2,3,5 = ipslateral eye