Visual Stimulus Recognition

Question 1

Features of the LGN

Answer 1

6 layers
Retinotopically organised
Layers alternate input from each eye
Ganglion cell axons make 1:1 projections with LGN projection neurons
Receptive fields of RGCs and LGN are similar
60% of the input is from back propagation from the cortex
LGN interneurons

Question 2

What are the two visual pathways in the cortex and what are they responsible for?

Answer 2

Dorsal - where

Ventral - what

Question 3

Describe the dorsal pathway

Answer 3

M-ganglion cells project to the magno LGN, which then projects to the V1 then V2 then V3. V3 projects to MT which is responsible for visual motion then to the parietal region which is responsible for intermediate object representation

Question 4

What are the basic principles behind the hierarchical model of object recognition?

Answer 4

Increasing response as complexity increases

Question 5

How do you test object recognition?

Answer 5

Lesions in inferior temporal - this decreases object recognition

Question 6

What are the three types of columns in the cortex?

Answer 6

Ocular dominance columns, direction columns and blobs, all make a hypercolumn

Question 7

Ocular dominance columns

Answer 7

Only found in one eye, each column either recieves input from ipsilateral or contralateral eye

Question 8

How can you detect ocular dominance columns?

Answer 8

Inject radioactive proline into one eye, inject glucose into the cortex (see stripes)

Question 9

Orientation columns

Answer 9

Column responds to horizontal/vertical/diagonal

Question 10

Blobs

Answer 10

Contain neurons that process information about colour