LGN

Question 1

LGN

Answer 1

Lateral Geniculate Nucleus, where the input from the optic nerve links. It consists of layers;

1 & 2 are Magnocellular
- Receive input from Parasol (Y) RGCs

3-6 are Parvocellular
- Receive input form Midget (X) RGCs

IC layers are Keniocellular
- Input uncertain

Contralateral eye
- Layer 1, 4 & 6

Ipsilateral eye
Layer 2, 3 and 5

Question 2

M-pathway

Answer 2

Fast cells, high temporal frequency so initial analysis of movement goes through this path

Question 3

P-pathway

Answer 3

Slower cells, analyses fine structure and color vision. Higher spatial frequency, lower temporal

Question 4

Other areas receiving visual info

Answer 4

Hypothalamus
- regulates the circadian rhythm

Pretectum
- Regulates pupil dilation and lens, eg when something comes closer, it narrows

Superior colliculus
- tracks motion, orientating movements, when a light/stimulus appears. Fairly automatic/ reflex mechanism

Question 5

Optic Chiasm

Answer 5

Place where the info meets from the two eyes. Right visual field is sent to the left hemi, the left visual field is sent to the right hemi.

A tumor for example can press on the chiams, causing defects in sight