Cog & Bio Vision

Question 1

What would happen if our eyes produced an accurate copy of the external world?

Answer 1

Illusions would not exist

Question 2

What is the basis of seeing?

Answer 2

Light rejected into our eyes from objects is the basis of seeing

Question 3

What is light sometimes defined as?

Answer 3

Waves of electromagnetic energy

Question 4

What is the length of waves of electromagnetic energy?

Answer 4

Between 380 and 760 nanometers in length - human visual system respond to these

Question 5

What is the iris?

Answer 5

Bands of contractile tissue that regulate the amount of light reaching the retina

Question 6

What is the pupil?

Answer 6

Hole in the centre of iris that allows light to enter the retina

Question 7

What happens in bright light?

Answer 7

Small pupil, better acuity (detail, focus resolution) - image is sharper

Question 8

What happens when it is dim?

Answer 8

Bigger pupil to let more light in, worse acuity, more sensitivity

Question 9

The amount of light reaching the retina is regulated by what?

Answer 9

The donut-shaped bands of contractile tissues & the irises

Question 10

What gives our eyes their characteristic colour?

Answer 10

The iris

Question 11

What represents a comprise between sensitivity and acuity?

Answer 11

Adjustment of pupil size in response to changes in illumination

Question 12

What happens when the level of illumination is high (and the sensitivity is thus not important) ?

Answer 12

This visual system contradicts the pupils - image falling on each retina is sharper

Question 13

What does the lens do?

Answer 13

Focuses light on the retina

Question 14

What do ciliary muscles do?

Answer 14

Alter the shape of the lens needed

Question 15

What is accommodation?

Answer 15

The process of adjusting the lens to bring images into focus

Question 16

The positions of the images in your retina can never what?

Answer 16

Correspond

Question 17

What is binocular disparity?

Answer 17

The difference in the position of the same image on the two retinas - greater for closer objects

Question 18

What do visual systems use to make 3D percept from the 2D retina images?

Answer 18

Binocular disparity

Question 19

What does the retina do with light?

Answer 19

Converts light into neural signals, conducts them towards the CNS and participates in the processing of the signals

Question 20

What’s at the back of the eye and what do they do?

Answer 20

Cone receptors - convert light into neuro signal and takes that to rod receptors

Question 21

What happens once the receptors have been activated?

Answer 21

The neural message is transmitted back out through the retinal layers to the retinal ganglion cells

Question 22

The inside-out arrangement create what 2 visual problems?

Answer 22

1. Incoming light is distorted by the retinal tissue through which it must pass before reaching the receptors
2. For The bundle of retina ganglion cell axons to leave the eye, there must be a gap in the receptor layer, this gap is called the blind spot

Question 23

What is photopic vision?

Answer 23

Good light, high acuity, colour (cone-mediated)

Question 24

What is scotopic vision?

Answer 24

Dim light, low acuity, high sensitivity, lacks colour (rod-mediated)

Question 25

More convergence in rod system does what?

Answer 25

Increases sensitivity whilst decreasing acuity

Question 26

What is only in the fovea?

Answer 26

Only cones

Question 27

More rods in the where compared to where

Answer 27

More rods in the nasal hemiretina than at temporal hemiretina

Question 28

What are the 3 involuntary fictional eye movements?

Answer 28

1. Tremour 2. Drifts 3. Saccades

Question 29

What are saccades?

Answer 29

Small jerky movements or flicks

Question 30

What is the striate cortex also known as?

Answer 30

Primary visual cortex or V1 (visual area 1)

Question 31

What 2 ways do signals from the left visual field reach the right primary visual cortex?

Answer 31

1. Ipsilaterally from the temporal hemiretina of the right eye 2. Contralaterally (via the optic chiasm) from the nasal hemiretina of the left eye - opposite is true of all signals from the right visual field

Question 32

How many layers does each lateral geniculate nucleus have?

Answer 32

6 layers

Question 33

Each layer of the geniculate nucleus receives what

Answer 33

Input from all parts of the contralateral visual field of one eye

Question 34

Where do the lateral geniculate neurons that project the primary visual cortex terminate?

Answer 34

In the lower part of the cortical layer IV

Question 35

What are the 4 top layers of Magno and Parvo LGN channels?

Answer 35

1. Parvocellular layers (small cell bodies) - colour, fine pattern details, stationary or slowing moving objects, majority of input provided by cones

Question 36

What are the 2 bottom layers of magno and parvo LGN channels?

Answer 36

Magnocellular layers (large cell bodies) - movement, majority of input provided by rods

Question 37

At least how many channels of communication flow through each lateral geniculate nucleus?

Answer 37

2 parallel channels

Question 38

Why are there 4 parvocellular layers?

Answer 38

2 from each eye

Question 39

Parvo LGN cells receive input from what?

Answer 39

Small midget ganglion cells

Question 40

Magno LGN cells receive inputs from what?

Answer 40

Large parasol ganglion cells

Question 41

What proportion of the primary visual cortex is dedicated to the analysis of the fovea output?

Answer 41

25%

Question 42

What are receptive fields?

Answer 42

Area of the visual field within which it is possible for a visual stimulus to influence the firing of that neuron

Question 43

What does the fovea mediate?

Answer 43

Fine grained (high acuity) vision

Question 44

All of the neurons (retinal ganglion cells, lateral geniculate neurons & lower layer IV neurons) all have what

Answer 44

Circular RFs

Question 45

All neurons are monocular - what does this mean?

Answer 45

Each neuron has a RF in one eye but not the other

Question 46

The neurons at each of the 3 levels of the retina-geniculate-striate system have RFs that what?

Answer 46

Comprise an excitatory area and an inhibitory area separated by a circular boundary

Question 47

RF of other layers of V1 can be divided into what?

Answer 47

On / off regions - straight lines (rectangular)

Question 48

What do on-centre and off-centre cells respond best to?

Answer 48

Contrast

Question 49

What is the most effective way to influence the firing rate of an on-centre or off-centre cell?

Answer 49

Maximise the contrast between the centre and the periphery of its receptive field by illuminating either the entire centre or the entire surrounding (periphery) while leaving the other region completely dark

Question 51

What is one function of many of the neurons in the retina-geniculate-striate system?

Answer 51

To respond to the degree of brightness contrast between the two areas of their receptive fields

Question 52

What is the difference between complex cells and simple cells in V1?

Answer 52

More numerous than simple cells

Question 53

What is similar between simple and complex cells?

Answer 53

Complex cells have rectangular RFs, respond best to straight line stimuli in a specific orientation, are unresponsive to diffuse light

Question 54

What is binocular?

Answer 54

Respond to stimulation of either eye

Question 55

Complex cells have larger…

Answer 55

RFs than simple cells & no static on off regions

Question 56

Complex cells respond to?

Answer 56

Straight edge stimuli of a particular orientation regardless of position within RF

Question 57

What do the simple and complex neurons not include

Answer 57

Neurons of lower layer IV

Question 58

What does V1 have?

Answer 58

A columnar organisation

Question 59

Where does the combination of information to be able to see take place?

Answer 59

In the visual association cortex

Question 61

The major flow of visual information in the cortex is from where to where?

Answer 61

From V1 to the various areas of secondary visual cortex to the areas of association cortex

Question 62

What happens as one moves up the visual hierarchy?

Answer 62

The neurons have larger receptive fields and the stimuli to which the neurons respond are more specific and more complex

Question 63

Most areas of secondary visual cortex are located in what 2 general regions!

Answer 63

Prestriatecortex and the inferotemporal cortex

Question 64

What is the prestriate cortex?

Answer 64

The band of tissue in the occipital lobe that surrounds the primary visual cortex

Question 65

What is the inferotemporal cortex?

Answer 65

The cortex of the inferior temporal lobe

Question 66

Where is the largest single area that receives visual input

Answer 66

In the posterior parietal cortex

Question 67

What did patient DF suffer from?

Answer 67

Hypoxia

Question 68

What is hemispatial neglect

Answer 68

Lack of awareness of the side of space opposite to the side of a brain lesion

Question 69

How do right hemisphere stroke patients behave?

Answer 69

As if the left side of the world ceased to exist

Question 70

What are the conventional measures used to assess neglect?

Answer 70

Pencil & paper tests - such as cancellation tasks, line bisecting & figure copying tasks

Question 71

In line bisection tasks, patients with left neglect will typically what?

Answer 71

Mark the centre more to the right than the true centre

Question 72

Pooled evidence of lesion location found what

Answer 72

The most common sites of damage was in the inferior parietal lobule and the superior temporal gyrus in the right hemisphere

Question 73

What is spatial neglect?

Answer 73

Radar system on left hand side no longer working well