Week 1

Question 1

How do we study perception

Answer 1

Direct- brain imaging and electrophysiology

Indirect- psychophysics

Question 2

The visual system is organised

Answer 2

Hierarchically

Question 3

Where is visual information transmitted

Answer 3

• The retina.
• The LGN.
• The primary visual cortex (V1).
• Other cortical regions specialised for vision

Question 4

The retina transduce light into neural signals using

Answer 4

Rods and cones

Question 5

Photosensitive pigment molecules are embedded in

Answer 5

The outer segments of rods and cones

Question 6

Photosensitive pigment molecules do what

Answer 6

Change their conformation in response to light and begin an intracellular signalling cascade that leads to an electrical signal

Question 7

How do rods and cones connect to the output cells of the retina

Answer 7

Connect to the bipolar cells

Question 8

What are the output cells of the retina called

Answer 8

The retinal ganglion cells

Question 9

How do horizontal cells and amacrine cells process visual information

Answer 9

Laterally

Question 10

What do bipolar cells do

Answer 10

• Make direct connections with a small number of photoreceptors
• Make indirect connections via the horizontal cells to the surrounding photoreceptors
• The connections cause opposite electrical responses in the bipolar cell

Question 11

What happens when light falls on the photoreceptors of the on-centre bipolar cells

Answer 11

Causes an excitatory response

Question 12

Light falling on photoreceptors in the receptive field surround cause

Answer 12

An inhibitory response

Question 13

A neuron’s receptive field will cause a response when

Answer 13

Photoreceptors at that area are stimulated by light

Question 14

For off centre bipolar cells, light falling on photoreceptors located at the centre of their receptive field causes

Answer 14

An inhibitory response

Question 15

or off centre bipolar cells, light falling on photoreceptors in the receptive field surround causes

Answer 15

An excitatory response

Question 16

What is fading

Answer 16

• Equal amounts of light are received by the receptive field centre and surround.
• Excitatory and inhibitory responses cancel each other out.
• The ganglion cell does not signal the presence of a stimulus

Question 17

Why don’t solid objects fade easily

Answer 17

Ganglion cells with receptive fields near the edge of the image signal strongly

Question 18

Retinal ganglion cells signal

Answer 18

Edge information

Question 19

Two classes of retinal ganglion cells

Answer 19

• Midget cells

- Parasol cells

Question 20

Are midget and parasol cells independent or connected

Answer 20

Independent parallel processing streams

Question 21

Midget cells

Answer 21

• Small receptive fields.
• Non sensitive to fast flicker.
• Red-green colour selective.
• ‘what’ stream.
• Connect to parvocellular LGN neurons

Question 22

Parasol cells

Answer 22

• Large receptive fields
• Sensitive to fast flicker
• Not colour selective
• ‘where’ stream
• Connect to magnocellular LGN neurons

Question 23

There are at least how many types of retinal ganglion cell

Answer 23

17

Question 24

Where is the lateral geniculate nucleus (LGN)

Answer 24

Part of the thalamus

Question 25

What does the LGN do

Answer 25

- Sends visual signals from the retina to the cortex. | - It’s neurons have a centre-surround receptive field

Question 26

Midget cells connect to

Answer 26

Parvocellular LGN neurons

Question 27

Parasol cells connect to

Answer 27

Magnocellular LGN neurons

Question 28

The structure of the receptive fields of neurons in V1 is

Answer 28

- Elongated to wire together retinal cells with neighbouring receptive fields. - Preferentially respond to oriented lines or edges

Question 29

Orientation selective cells in V1 are known as

Answer 29

Simple cells

Question 30

The complexity of receptive fields builds through the visual hierarchy by

Answer 30

Wiring together neurons at lower levels

Question 31

The theoretical pinnacle is grandmother cells which

Answer 31

Have receptive fields that would be specific for one individual object

Question 32

Cells in area TEO in the ventral stream have

Answer 32

Moderately complex receptive fields

Question 33

Quiroga et al 2005 found cells in human temporal cortex that responded

Answer 33

Selectively to images of one person or object

Question 34

What is sparse code

Answer 34

A network of neurons would represent each context

Question 35

The neurons in visual cortical areas are

Answer 35

- Retinotopically mapped | - Neighbouring neurons respond to neighbouring regions on the retina

Question 36

Orientation preference is organised how in the primary visual cortex (V1)

Answer 36

- Systematically. | - Neighbouring columns of neurons have systematically different orientation preferences

Question 37

What are ocular dominance columns

Answer 37

Inputs from two eyes are systematically interleaved

Question 38

What is a hypercolumn

Answer 38

A section of V1 that represents all orientations for both eyes

Question 39

Different populations of V1 neurons are also sensitive to

Answer 39

Different spatial frequencies

Question 40

The contrast sensitivity function describes

Answer 40

- Human contrast sensitivity as a function of spatial frequency - Peaks at medium spatial frequencies

Question 41

The contrast sensitivity function is a result of

Answer 41

The combined responses of a population of different neurons sensitive to different ranges of spatial frequency

Question 42

Only the adapted neurons show

Answer 42

A reduction in contrast sensitivity

Question 43

Spatial frequency is encoded by

Answer 43

- Population code. | - Over a population of neurons sensitive to different spatial frequencies

Question 44

Neurons selective for low spatial frequencies encode

Answer 44

Broad patterns of light and dark

Question 45

Neurons selective for high spatial frequencies encode

Answer 45

Finer detail

Question 46

Cortical area V5 (MR) is specialised for

Answer 46

Processing motion

Question 47

The waterfall illusion reveals that motion is encoded via

Answer 47

- An opponent code. | - After adaption in one direction, illusory motion is perceived in the opposite direction

Question 48

Reinhardt detectors can detect

Answer 48

- Motion | - Located in a fly

Question 49

The complexity of receptive fields increases or decreases through the visual hierarchy

Answer 49

Increases