Chapter 3

Question 1

What is the general visual pathway from retina to cortex?

Answer 1

Retina ➡️Optic Nerves ➡️ Optic Chasm ➡️Lateral Geniculate Nucleus (LGN) ➡️Primary Visual Cortex (V1).

Question 2

Where do optic nerve fibres meet and partially cross?

Answer 2

At the optic chiasm.

Question 3

Which side of the brain processes the left visual field?

Answer 3

The right hemisphere (and vice versa).

Question 4

What are nasal and temporal retinas?

Answer 4

Nasal: side closest to nose; Temporal: side closest to temples.

Question 5

Where is the Lateral Geniculate Nucleus (LGN) located?

Answer 5

In the thalamus.

Question 6

How many layers does the LGN have?

Answer 6

6 layers: 1–2 magnocellular, 3–6 parvocellular.

Question 7

What do magnocellular layers process?

Answer 7

Motion and perception (from M cells).

Question 8

What do parvocellular layers process?

Answer 8

Colour and form (from P cells).

Question 9

Which LGN layers receive input from the contralateral eye?

Answer 9

Layers 1, 4, 6.

Question 10

Which LGN layers receive input from the ipsilateral eye?

Answer 10

Layers 2, 3, 5.

Question 11

What does the dorsal stream process?

Answer 11

Where/how information: motion, spatial location (parietal lobe).

Question 12

What does the ventral stream process?

Answer 12

What information: object recognition, colour, form (temporal lobe).

Question 13

What is another name for the primary visual cortex?

Answer 13

Striate cortex or V1.

Question 14

What replaces circular receptive fields from LGN in V1?

Answer 14

Elongated bar-shaped receptive fields.

Question 15

What is topographic (retinotopic) mapping?

Answer 15

Spatial arrangement of visual field is preserved in V1.

Question 16

What is cortical magnification?

Answer 16

Foveal inputs occupy disproportionately large areas of V1.

Question 17

What is visual crowding?

Answer 17

Reduced resolution in peripheral vision causing clutter effects.

Question 18

What do simple cells in V1 respond best to?

Answer 18

Bars of light with specific orientation and location.

Question 19

What do complex cells respond to?

Answer 19

Bars of light or dark with a specific orientation anywhere in their receptive field.

Question 20

What do end-stopped cells respond to?

Answer 20

Bars of a specific length; selective for line endings.

Question 21

Who discovered V1 receptive field shapes?

Answer 21

David Hubel and Torsten Wiesel.

Question 22

How do spots become stripes in V1 processing?

Answer 22

Aligned ganglion cells with circular fields converge onto one simple cell, forming bar-shaped receptive fields.

Question 23

Which V1 layers receive magnocellular input?

Answer 23

Layer 4Cα.

Question 24

Which V1 layers receive parvocellular input?

Answer 24

Layer 4Cβ.

Question 25

Which V1 layers receive koniocellular input?

Answer 25

Layers 2 and 3.

Question 26

What is an orientation column?

Answer 26

A column of cells responsive to a specific orientation of light.

Question 27

What is an ocular dominance column?

Answer 27

Columns of cells preferring input from one eye over the other.

Question 28

What is a hypercolumn?

Answer 28

A complete set of orientation and ocular dominance columns for a small region of visual field.

Question 29

What is adaptation?

Answer 29

Reduction in neural response after sustained stimulation.

Question 30

What is selective adaptation?

Answer 30

Prolonged exposure to one stimulus deactivates neurons tuned to that orientation, shifting perceived orientation.

Question 31

What defines different visual areas beyond V1?

Answer 31

Neuron types, connectivity, and stimulus tuning (motion, colour, etc.).

Question 32

Is retinotopic mapping preserved beyond V1?

Answer 32

Yes, in each visual area.

Question 33

What pathway is involved in motion processing?

Answer 33

Dorsal stream (V1 → V2 → MT → Parietal lobe).

Question 34

What pathway is involved in object identity processing?

Answer 34

Ventral stream (V1 → V2 → V4 → Inferotemporal cortex).

Question 35

What happens with dorsal stream lesions?

Answer 35

Trouble locating objects (where/how tasks).

Question 36

What happens with ventral stream lesions?

Answer 36

Trouble recognizing objects (what tasks).

Question 37

Who was Patient DF and what was her condition?

Answer 37

She had visual form agnosia from ventral stream damage; could see but not recognize shapes.

Question 38

What task could Patient DF perform correctly?

Answer 38

Posting a letter (visuomotor task).

Question 39

What task could Patient DF not perform?

Answer 39

Aligning or identifying object orientation; manual size estimation.

Question 40

What is processed in V4?

Answer 40

Colour, edges, and curvature; contour-selective receptive fields.

Question 41

What do the LOC and IT areas process?

Answer 41

Objects, faces, and places.

Question 42

What area responds best to faces?

Answer 42

Fusiform Face Area (FFA).

Question 43

What area responds best to places?

Answer 43

Parahippocampal Place Area (PPA).

Question 44

What area responds best to bodies and body parts?

Answer 44

Extrastriate Body Area (EBA).

Question 45

What is the grandmother cell hypothesis?

Answer 45

Idea that single neurons code for specific people or objects (unlikely).

Question 46

What is the distributed coding hypothesis?

Answer 46

Representation arises from patterns of activity across many neurons.

Question 47

Which brain area processes motion?

Answer 47

Area MT (V5).