Vision

Question 1

Path to the cortex:

Answer 1

1) Outside world
2) Retina
3) Optical chiasm/nerve
4) LGN e SC (thalamus)
5) Optical radiation
6) Primary visual cortex

Question 2

The visual field of human eye are overlapping. The consequence is that:

Answer 2

-> information from the left visual field: right brain
-> information from the right visual field: left brain

Question 3

The retina have 2 cells:

Answer 3

1) Rods -> scotopic system (night vision)
2) Cones -> photopic system (day vision)

Question 4

The rods cells are

Answer 4

hyperpolarized (less chance of action potential).

Question 5

lateral inhibition

Answer 5

neighbour cells send a signal to the neighbour for inhibit them. This function serve to detect edges and contours.

Question 6

Blindsight

Answer 6

cortical blindness. Damage to V1 can lead to blindness for stimulus that are in the receptive field of those cortical regions.

Question 7

Evolution of the eye

Answer 7

slow process, the only requirement appears to be the existence of light-sensitive cells

Question 8

Thalamus

Answer 8

main gateway between external organs and the cortex.

Question 9

LGN

Answer 9

lateral geniculate nucleus, composed by multiple layers (6), input from cones and rods. LGN receptive field have very similar organisation compared to ganglion cells (centre on, lateral off).

Question 10

Hubel and Wiesel discover

Answer 10

ice cube model of visual cortex, different cells that respond to stimuli with different orientations -> orientation columns and ocular dominance column.

Question 11

Simple cortical cells

Answer 11

get information from NGN -> understand the bar of light. They are composed by 3 ganglion cells that project into it -> a bar of light is projected into the screen.

Question 12

Complex cells

Answer 12

receive information from simple cortical cells -> complex perceive the motion of the bar of light.

Question 13

2 theories for colour vision

Answer 13

• Von Helmholtz: trichromatic hypothesis -> 3 kinds of receptors (blue, green and red) that composed the entire spectrum
• Herringer: opponent-process hypothesis -> blue vs yellow, red vs green and black vs white.

Question 14

2 visual pathways:

Answer 14

1) Dorsal (where) -> where the stimuli occur in the environment (more magnocellular). It is fast, motion sensitive and it guides action

2)Ventral (what) -> more parvocellular. It identify colours, precise shape and it interact with memory (slower).

Question 15

When you see an object in your left visual field, the information from LGN arrive at

Answer 15

the contralateral occipital cortex (not confuse right eye with right visual field)

Question 16

When light falls onto the retina, it

Answer 16

hyperpolarises receptor cells (less neurotransmitter being release -> 2 possible effects, depending on the type of cells)

Question 17

In the retina the fovea contains mostly

Answer 17

cones, because they are particularly good for processing colour vision and day light (while outside mostly rods)

Question 18

When light falls on the retina outside the fovea, the first cells it reaches are

Answer 18

ganglion cells (they cover the entire area, they are being activated all the time). In other species that live in deep sea (don’t need light see) the receptor are at the front of the retina -> natura arrangement of the retina

Question 19

Patients with blindsight have suffered damage to

Answer 19

the primary visual cortex (paradox, something to do with superior colliculus .. )

Question 20

The mechanism of colour vision in ganglion and LGN cells is

Answer 20

spectral opponency (important to consider the theory

Question 21

Jennifer Aniston cells were found in

Answer 21

Hippocampus