Vision

Question 1

Visual processing from the retina to the brain

Answer 1

RGCs send axons through the optic nerve
There can be no photoreceptors where the nerve starts
This is why we have a blind spot in our field of view

Question 2

How is each retina divided

Answer 2

Into nasal hemiretina and temporal hemiretina
Their projections diverge at the optic chiasm
Nasal hemiretinas cross over
Result: the left visual field is represented in the right hemisphere and vice versa

Question 3

Lateral Geniculate Nucleus (LGN)

Answer 3

RGC axons reach the LGN of the thalamus
LGN has 6 layers:
Layers 1-2: Magnocellullar (big cells)
-Motion and dim light sensitive from rods
Layers 3-6: Parvocellular (small cells)
-Color and detail resolution from cones

Question 4

LGN receptive fields

Answer 4

Center-surround like retinal ganglion cells
Bigger receptive fields than RGCs
-See a larger chunk of visual space

Question 5

From the LGN to the cortex

Answer 5

Axons from LGN travel through the optic radiations to the Primary Visual Cortex (V1)
Maintains retinotopic organization:
1. Each V1 neuron responds to a stimulus in a small area in the field of view, and
2. Neighboring V1 neurons respond to stimuli in nearby locations in the visual field