Principles of Neuroscience Lecture 7, Vision, Further pathways

Question 0

What are the two types of ganglion cells and describe their features

Answer 0

Mango cellular type : large, involved in motion detection, Parasol shape

Parvo cellular : small, involved with colour and visual acuity

Question 1

Describe the path of information from the retina

Answer 1

Retina - photoreceptor cells - optic nerve - Lateral Geniculate nucleus in Thalamus - Primary Visual cortex

Question 2

Describe the structural arrangement in the Lateral Geniculate Nucleus

Answer 2

LGN is located in the thalamus

There are six layers in the LGN that have input from either of the different types of ganglion cell.

Layers 1 & 2 : Magnocellular
Layers 3,4,5 & 6 : Parvocellular

Question 3

Describe the functional divisions in the occipital lobe

Answer 3

V1 : primary visual cortex. Receives information from the thalamus (LGN) by the calcarine fissures
V2,3 : areas to which information travels next.

Question 4

What is V1?

Answer 4

Primary Visual Cortex

Question 5

Describe the functional layers in V1.

Into which layer does the LGN input information?

Answer 5

There are 6 layers of neurons. 
1
2 & 3
4A
4B
4C
5
6

The LGN inputs information into 4C (within 4C are more divisions)

Question 6

What is important about the organisation of information in V1?

Answer 6

Retinotopic organisation : the same mapping from the retina is maintained in V1

Contralateral representation of visual fields

Question 7

At what point does information from each eye get combined?

Answer 7

M - type information : at 4B

P - type information : at 3

Question 8

What are the pathways that information takes after the Primary Visual Cortex?

Answer 8

Dorsal : where is the thing I’m seeing –> motion. Naturally, this comes from M-cells.
Information goes from V1 - V2 - V3 - MT(middle temporal lobe)

Ventral: What is the thing I’m seeing? –> colour and shape.
This is derived from P-type information.
Information feeds from V1 - V2 - V3 - V4 - IT (inferior temporal lobe)

Question 9

Into which layer does LGN input information in the V1?

Specifically, into which layers is P type and M type information fed?

Answer 9

4C.
P - type : 4C beta
M - type : 4C alpha

Question 10

Which cell is also called midget?

Answer 10

Parvocellular ganglion cell

Question 11

Describe orientational selectivity.

Which neurons exhibit this?

Answer 11

Neurons respond most strongly to bars moving at certain rotations

Only the neurons in the visual cortex

Question 12

Which type of cell is described as parasol

Answer 12

Magnocllular ganglion cell

Question 13

What does orientation all selectivity mean for vision?

Answer 13

This means we can see edges of objects clearly

Question 14

Input from LGN into the V1 is isolated to …

Answer 14

Ocular dominance columns

Question 15

Within a column of the V1, the 6 layers respond to light in … Orientations

Answer 15

The same

Question 16

Which region is important for colour, shape, facial recognition, visual memory, visual perception

Answer 16

IT

Question 17

Differentiate between the functions of the IT and the MT

Answer 17

IT: inferior temporal lobe; colour, shape, visual memory, faces

MT: medial temporal lobe: motion

Question 18

Which region is damaged when people are unable to detect motion?

Answer 18

MT

Question 19

Describe the grey hound slide

Answer 19

Different columns of neurons detect light at different rotations.

This is then integrated to give a compete image

Question 20

What is the function of the IT?

Answer 20

The neurons here respond to shape and colour

Visual memory and perception (especially faces)

Question 21

Which region is damaged when people are unable to recognise faces?

Answer 21

IT